How to find all occurrences of string in a string Java

 Find all occurrences of string in a string. for this we will use one loop and indexof() method

public class StringCheck {
   
    public static void main(String[] args) {
       
        String str = "delhi is good city in india and india also good. there are many city good and people also good" +
                "so india is good country ";
        String mystr = "good";
        int index =0;
   while(index != -1){
       index = str.indexOf(mystr, index+1);
        System.out.println("index is = "+index);
   };
       
    }
}

Output:

index is = 9

index is = 43

index is = 69

index is = 90

index is = 106

index is = -1

How to delete all elements from TreeMap

import java.util.Map;
import java.util.TreeMap;

public class TreeMapDeleteAll {

   
    public static void main(String[] args) {
       
        Map<Integer, String> tm = new TreeMap<Integer,String>();
       
        // add key and values
        tm.put(1,"java");
        tm.put(2,"cpp");
        tm.put(3,"php");
        tm.put(4,"c");
        tm.put(5, "mysql");
       
        //print treemap
   
        System.out.println("Before Clear TreeMap Is="+tm);
       
        //Removes all of the mappings from this map
        tm.clear();
       
        System.out.println("After Clear TreeMap Is ="+tm);
       
    }
   
}




Output:


Before Clear TreeMap Is={1=java, 2=cpp, 3=php, 4=c, 5=mysql}

After Clear TreeMap Is ={}

How to get entry set from TreeMap

import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.TreeMap;

public class TreeMapEntrySet {
   
    public static void main(String[] args) {
       
        Map<Integer, String> tm = new TreeMap<Integer,String>();
       
        // add key and values
        tm.put(1,"java");
        tm.put(2,"cpp");
        tm.put(3,"php");
        tm.put(4,"c");
        tm.put(5, "mysql");
       
        //print treemap
   
        System.out.println("TreeMap Is="+tm);
       
        //Returns a Set view of the mappings contained in this
        // map
        Set<Entry<Integer, String>> entry =tm.entrySet();
       
        for (Entry<Integer, String> entry2 : entry) {
            System.out.println("key ="+entry2.getKey()+" value ="+entry2.getValue());
        }
       
    }

}




Output:


TreeMap Is={1=java, 2=cpp, 3=php, 4=c, 5=mysql}

key =1 value =java

key =2 value =cpp

key =3 value =php

key =4 value =c

key =5 value =mysql

How to get size of TreeMap

import java.util.Map;
import java.util.TreeMap;

public class TreeMapKeyCount {
   
    public static void main(String[] args) {
       
        Map<Integer, String> tm = new TreeMap<Integer,String>();
       
        // add key and values
        tm.put(1,"java");
        tm.put(2,"cpp");
        tm.put(3,"php");
        tm.put(4,"c");
        tm.put(5, "mysql");
       
        //print treemap
   
        System.out.println("TreeMap Is="+tm);

        //Returns the number of key-value mappings in this map
       
        System.out.println("size of treemap = "+tm.size());
       
    }

}

Output:

TreeMap Is={1=java, 2=cpp, 3=php, 4=c, 5=mysql}

size of treemap = 5

How to get all keys of TreeMap

import java.util.Map;
import java.util.Set;
import java.util.TreeMap;

public class TreeMapGetAllKeys {
   
    public static void main(String[] args) {
       
        Map<Integer, String> tm = new TreeMap<Integer,String>();
       
        // add key and values
        tm.put(1,"java");
        tm.put(2,"cpp");
        tm.put(3,"php");
        tm.put(4,"c");
        tm.put(5, "mysql");
       
        //Returns a Set view of the keys contained in this map.
       
        Set<Integer> keys = tm.keySet();
       
        for (Integer key : keys) {
            System.out.println("key = "+key);
        }
       
    }

}







Output:



key = 1

key = 2

key = 3

key = 4

key = 5

How to get value of key in TreeMap

import java.util.Map;
import java.util.TreeMap;

public class TreeMapGetValueOfkey {
   
    public static void main(String[] args) {
       
        Map<Integer, String> tm = new TreeMap<Integer,String>();
       
        // add key and values
        tm.put(1,"java");
        tm.put(2,"cpp");
        tm.put(3,"php");
        tm.put(4,"c");
        tm.put(5, "mysql");
       
    /*
     * Returns the value to which the specified key is
       mapped, or null if this map contains no mapping for
       the key.
     */
      System.out.println("key =1  and value ="+tm.get(1));
      System.out.println("key =1 and value ="+tm.get(5));
      System.out.println("key =1 and value ="+tm.get(10));
      
       
    }

}

Output:

key =1  and value =java

key =1 and value =mysql

key =1 and value =null

How to Search Value in TreeMap Java

import java.util.Map;
import java.util.TreeMap;

public class TreeMapSearchValue {

    public static void main(String[] args) {
       
        Map<Integer, String> tm = new TreeMap<Integer,String>();
       
        // add key and values
        tm.put(1,"java");
        tm.put(2,"cpp");
        tm.put(3,"php");
        tm.put(4,"c");
        tm.put(5, "mysql");
       
        //print treemap
   
        System.out.println("TreeMap Is="+tm);
   
        System.out.println(tm.containsValue("java"));
        System.out.println(tm.containsValue("data design"));
        System.out.println(tm.containsValue("html"));
        System.out.println(tm.containsValue("php"));
       
    }
   
   
}

Output:

TreeMap Is={1=java, 2=cpp, 3=php, 4=c, 5=mysql}

true

false

false

true

How to Search key in TreeMap Java

import java.util.Map;
import java.util.TreeMap;

public class TreeMapSearchKey {
   
    public static void main(String[] args) {
       
        Map<Integer, String> tm = new TreeMap<Integer,String>();
       
        // add key and values
        tm.put(1,"java");
        tm.put(2,"cpp");
        tm.put(3,"php");
        tm.put(4,"c");
        tm.put(5, "mysql");
       
        //print treemap
   
        System.out.println("TreeMap Is="+tm);
        System.out.println(tm.containsKey(1));
        System.out.println(tm.containsKey(18));
        System.out.println(tm.containsKey(3));
        System.out.println(tm.containsKey(25));
       
       
    }

}

Output:

TreeMap Is={1=java, 2=cpp, 3=php, 4=c, 5=mysql}

true

false

true

false

How to storing Java Object In TreeMap

import java.util.Map;
import java.util.Set;
import java.util.TreeMap;

public class TreeMapStoreObject {

    public static void main(String[] args) {
       
    Map<Integer, Emp> tm = new TreeMap<Integer, Emp>();
   
    tm.put(1, new Emp("yogesh", 100));
    tm.put(2, new Emp("shivam", 200));
    tm.put(3, new Emp("ankush",250));
    tm.put(4, new Emp("anurag",300));
    tm.put(5, new Emp("ravi", 370));
   
    //Returns a Set view of the keys contained in this map.
    Set<Integer> keys = tm.keySet();
   
    for (Integer key : keys) {
        Emp emp = tm.get(key);
        System.out.println(" key ="+ key +" name ="+emp.getName()+" id = "+ emp.getName());
    }
 }
}

class Emp{
    private String name;
    private int id;
   
    public Emp(String name, int id) {
        this.name = name;
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }
   
}

Output:

 key =1 name =yogesh id = yogesh

 key =2 name =shivam id = shivam

 key =3 name =ankush id = ankush

 key =4 name =anurag id = anurag

 key =5 name =ravi id = ravi

How to iterate through TreeMap

import java.util.Map;
import java.util.Set;
import java.util.TreeMap;

public class TreeMapIterate {
   
    public static void main(String[] args) {
       
        Map<Integer, String> tm = new TreeMap<Integer,String>();
       
        // add key and values
        tm.put(1,"java");
        tm.put(2,"cpp");
        tm.put(3,"php");
        tm.put(4,"c");
        tm.put(5, "mysql");
       
        //Returns a Set view of the keys contained in this map
       
        Set<Integer> keys = tm.keySet();
       
        for (Integer key : keys) {
            System.out.println(" key ="+key+" value ="+tm.get(key));
        }
       
    }

}

Output:

 key =1 value =java

 key =2 value =cpp

 key =3 value =php

 key =4 value =c

 key =5 value =mysql

How to create TreeMap In Java

import java.util.Map;
import java.util.TreeMap;

public class CreateTreeMap {

    public static void main(String[] args) {
       
        Map<Integer, String> tm = new TreeMap<Integer,String>();
       
        // add key and values
        tm.put(1,"java");
        tm.put(2,"cpp");
        tm.put(3,"php");
        tm.put(4,"c");
        tm.put(5, "mysql");
       
        //print treemap
   
        System.out.println("TreeMap Is="+tm);
       
    }
   
}





Output:


TreeMap Is={1=java, 2=cpp, 3=php, 4=c, 5=mysql}

Java TreeMap Examples

How to create TreeMap In Java

How to iterate through TreeMap  

How to storing Java Object In TreeMap

How to Search key in TreeMap Java 

How to Search Value in TreeMap Java

How to delete all elements from HashMap

import java.util.HashMap;
import java.util.Map;

public class HashMapDeleteAll {
   
    public static void main(String[] args) {
       
    Map<Integer,String> hm = new HashMap<Integer,String>();
       
    /*
     * Associates the specified value with the specified key in
       this map (optional operation). If the map previously
       contained a mapping for the key, the old value is
       replaced by the specified value
     */
        hm.put(1,"ankush");
        hm.put(2, "amit");
        hm.put(3,"shivam");
        hm.put(4,"ankit");
        hm.put(5, "yogesh");
       
        //print hashmap
        System.out.println("Before Clear HashMap is = "+hm);
       
        /*
         * The map will be empty after this call returns.
         */
       
        hm.clear();
       
        System.out.println("After Clear HashMap is ="+hm);
       
    }

}

OutPut:

Before Clear HashMap is = {1=ankush, 2=amit, 3=shivam, 4=ankit, 5=yogesh}

After Clear HashMap is ={}

How to get entry set from HashMap

import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

public class HashMapEntrySet {
   
    public static void main(String[] args) {
       
    Map<Integer,String> hm = new HashMap<Integer,String>();
       
    /*
     * Associates the specified value with the specified key in
       this map (optional operation). If the map previously
       contained a mapping for the key, the old value is
       replaced by the specified value
     */
        hm.put(1,"ankush");
        hm.put(2, "amit");
        hm.put(3,"shivam");
        hm.put(4,"ankit");
        hm.put(5, "yogesh");
       
        //print hashmap
        System.out.println("HashMap = "+hm);
       
        Set<Entry<Integer, String>> entry =hm.entrySet();
       
        for (Entry<Integer, String> entry2 : entry) {
            System.out.println(" Key = "+entry2.getKey()+" Value = "+entry2.getValue());
        }
    }

}




Output:

 HashMap = {1=ankush, 2=amit, 3=shivam, 4=ankit, 5=yogesh}

 Key = 1 Value = ankush

 Key = 2 Value = amit
 
 Key = 3 Value = shivam

 Key = 4 Value = ankit

 Key = 5 Value = yogesh

How to get size of HashMap

import java.util.HashMap;
import java.util.Map;

public class HashMapKeyCount {
   
    public static void main(String[] args) {
       
        Map<Integer,String> hm = new HashMap<Integer,String>();
           
        /*
         * Associates the specified value with the specified key in
           this map (optional operation). If the map previously
           contained a mapping for the key, the old value is
           replaced by the specified value
         */
            hm.put(1,"ankush");
            hm.put(2, "amit");
            hm.put(3,"shivam");
            hm.put(4,"ankit");
            hm.put(5, "yogesh");
           
            //Returns the number of key-value mappings in this map
           
            System.out.println("HashMap size = "+hm.size());
           
           
        }
   
}

Output:

HashMap size = 5

How to get all keys of HashMap

import java.util.HashMap;
import java.util.Map;
import java.util.Set;

public class HashMapGetAllKeys {



        public static void main(String[] args) {
           
        Map<Integer,String> hm = new HashMap<Integer,String>();
           
        /*
         * Associates the specified value with the specified key in
           this map (optional operation). If the map previously
           contained a mapping for the key, the old value is
           replaced by the specified value
         */
            hm.put(1,"ankush");
            hm.put(2, "amit");
            hm.put(3,"shivam");
            hm.put(4,"ankit");
            hm.put(5, "yogesh");
           
            /*
             * Returns a Set view of the keys contained in this map
             */
           
            Set<Integer> keys =hm.keySet();
           
            for (Integer key : keys) {
                System.out.println(" key ="+key);
            }
        }
   
}

Output:

  key =1

  key =2

  key =3

  key =4
 
  key =5

How to get value of key in HashMap

import java.util.HashMap;
import java.util.Map;

public class HashMapGetValueOfkey {
    public static void main(String[] args) {
       
    Map<Integer,String> hm = new HashMap<Integer,String>();
       
    /*
     * Associates the specified value with the specified key in
       this map (optional operation). If the map previously
       contained a mapping for the key, the old value is
       replaced by the specified value
     */
        hm.put(1,"ankush");
        hm.put(2, "amit");
        hm.put(3,"shivam");
        hm.put(4,"ankit");
        hm.put(5, "yogesh");
       
        /*
         * Returns the value to which the specified
         * key is mapped, or null if this map contains
         *  no mapping for the key.
         */
       
        System.out.println(" key = 1 and value = "+hm.get(1));
        System.out.println(" key = 1 and value = "+hm.get(10));
       
        System.out.println(" key = 1 and value = "+hm.get(5));
        System.out.println(" key = 1 and value = "+hm.get(4));
       
    }

}

Output:

 key = 1 and value = ankush

 key = 1 and value = null

 key = 1 and value = yogesh

 key = 1 and value = ankit

How to Search Value in HashMap Java

import java.util.HashMap;
import java.util.Map;

public class HashMapSearchValue {

    public static void main(String[] args) {
      
        Map<Integer,String> hm = new HashMap<Integer,String>();
          
        /*
         * Associates the specified value with the specified key in
           this map (optional operation). If the map previously
           contained a mapping for the key, the old value is
           replaced by the specified value
         */
            hm.put(1,"ankush");
            hm.put(2, "amit");
            hm.put(3,"shivam");
            hm.put(4,"ankit");
            hm.put(5, "yogesh");
          
            System.out.println(" value john ="+hm.containsValue("john"));
            System.out.println(" value amit ="+hm.containsValue("amit"));
          
            System.out.println(" value piyush ="+hm.containsValue("piyush"));
            System.out.println(" value shivam ="+hm.containsValue("shivam"));
          
        }

}

Output;

 value john =false

 value amit =true

 value piyush =false

 value shivam =true

How to Search key in HashMap Java

import java.util.HashMap;
import java.util.Map;

public class HashMapSearchKey {
    public static void main(String[] args) {
       
    Map<Integer,String> hm = new HashMap<Integer,String>();
       
    /*
     * Associates the specified value with the specified key in
       this map (optional operation). If the map previously
       contained a mapping for the key, the old value is
       replaced by the specified value
     */
        hm.put(1,"ankush");
        hm.put(2, "amit");
        hm.put(3,"shivam");
        hm.put(4,"ankit");
        hm.put(5, "yogesh");
       
        /*
         * Returns true if this map contains a
         *  mapping for the specified key
         */
   
    System.out.println("key  1   ="+hm.containsKey(1));
    System.out.println("key  20  ="+hm.containsKey(20));
    System.out.println("key 9    ="+hm.containsKey(9));
    System.out.println("key  5   ="+ hm.containsKey(5));
       
    }
}


Output:
key  1   =true

key  20  =false

key 9    =false

key  5   =true

How to storing Java Object In HashMap

import java.util.HashMap;
import java.util.Map;
import java.util.Set;

public class HashMapStoreObject {
   
    public static void main(String[] args) {
       
        Map<Integer,Emp> hm = new HashMap<Integer, Emp>();
       
        hm.put(1, new Emp(100, "dk") );
        hm.put(2, new Emp(102, "kapil") );
        hm.put(3, new Emp(105, "anup") );
        hm.put(4, new Emp(205, "kapil") );
        hm.put(5, new Emp(110, "pk") );
       
           Set<Integer> keys = hm.keySet();
      
           for (Integer key : keys) {
              
               Emp emp = hm.get(key);
            System.out.println(" Id = "+emp.getId()+" name = "+emp.getName());
        }
          
    }

}


class Emp{
   
        private int id;
        private String name;
       
        public Emp(int id, String name) {
            this.id = id;
            this.name = name;
        }
        public int getId() {
            return id;
        }
        public void setId(int id) {
            this.id = id;
        }
        public String getName() {
            return name;
        }
        public void setName(String name) {
            this.name = name;
        }
       
}




Output:

 Id = 100 name = dk

 Id = 102 name = kapil

 Id = 105 name = anup

 Id = 205 name = kapil

 Id = 110 name = pk

How to iterate through HashMap

import java.util.HashMap;
import java.util.Map;
import java.util.Set;

public class HashMapIterate {
   
    public static void main(String[] args) {
       
    Map<Integer,String> hm = new HashMap<Integer,String>();
       
    /*
     * Associates the specified value with the specified key in
       this map (optional operation). If the map previously
       contained a mapping for the key, the old value is
       replaced by the specified value
     */
        hm.put(1,"ankush");
        hm.put(2, "amit");
        hm.put(3,"shivam");
        hm.put(4,"ankit");
        hm.put(5, "yogesh");
       
       Set<Integer> keys = hm.keySet();
      
       for (Integer key : keys) {
        System.out.println("key ="+key+" value = "+hm.get(key));
    }
       
       
    }
   

}


Output:

key =1 value = ankush

key =2 value = amit

key =3 value = shivam

key =4 value = ankit

key =5 value = yogesh

How to create HashMap In Java

import java.util.HashMap;
import java.util.Map;

public class CreateHashMap {

    public static void main(String[] args) {
       
    Map<Integer,String> map = new HashMap<Integer,String>();
       
    /*
     * Associates the specified value with the specified key in
       this map (optional operation). If the map previously
       contained a mapping for the key, the old value is
       replaced by the specified value
     */
        map.put(1,"ankush");
        map.put(2, "amit");
        map.put(3,"shivam");
        map.put(4,"ankit");
        map.put(5, "yogesh");
       
        //print hashmap
        System.out.println("HashMap = "+map);
       
       
    }
   
}




Output:


HashMap = {1=ankush, 2=amit, 3=shivam, 4=ankit, 5=yogesh}

Java HashMap Examples

How to create HashMap In Java

How to iterate through HashMap 

How to storing Java Object In HashMap

How to Search key in HashMap Java

How to Search Value in HashMap Java 

How to get value of key in HashMap

 How to get all keys of HashMap

How to get size of HashMap

How to get entry set from HashMap

 How to delete all elements from HashMap

How to create shallow copy of Hashtable

import java.util.Hashtable;

public class HashTableShallowCopy {
    public static void main(String[] args) {
       
        Hashtable<Integer,String> ht = new Hashtable<Integer,String>();
       
        /*
         * Maps the specified key to the specified
         * value in this hashtable
         */
        ht.put(1, "java");
        ht.put(2, "jersey");
        ht.put(3, "spring");
        ht.put(4, "c");
        ht.put(5, "php");
       
        //print hashtable
        System.out.println(" Hash Table is ="+ht);
       
      //Creates a shallow copy of this hashtable.
      Hashtable<Integer,String> myHt = (Hashtable<Integer, String>) ht.clone();
   
      System.out.println(" shallow copy ="+myHt);
     
    }   

}


Output:

 Hash Table is ={5=php, 4=c, 3=spring, 2=jersey, 1=java}

 shallow copy ={5=php, 4=c, 3=spring, 2=jersey, 1=java}

How to get elements using Enumeration from Hashtable

import java.util.Enumeration;
import java.util.Hashtable;

public class HashTableGetEnumeration {

    public static void main(String[] args) {

        Hashtable<Integer, String> ht = new Hashtable<Integer, String>();

        /*
         * Maps the specified key to the specified value in this hashtable
         */
        ht.put(1, "java");
        ht.put(2, "jersey");
        ht.put(3, "spring");
        ht.put(4, "c");
        ht.put(5, "php");

        // Returns an enumeration of the keys in this hashtable

        Enumeration<Integer> keys = ht.keys();

        while (keys.hasMoreElements()) {
            int key = keys.nextElement();

            System.out.println(" key = " + key + " value = " + ht.get(key));

        }

    }

}



Output:

 key = 5 value = php

 key = 4 value = c

 key = 3 value = spring

 key = 2 value = jersey

 key = 1 value = java

How to delete all elements from Hashtable

import java.util.Hashtable;

public class HashtableDeleteAll {

    public static void main(String[] args) {
       
        Hashtable<Integer,String> ht = new Hashtable<Integer,String>();
       
        /*
         * Maps the specified key to the specified
         * value in this hashtable
         */
        ht.put(1, "java");
        ht.put(2, "jersey");
        ht.put(3, "spring");
        ht.put(4, "c");
        ht.put(5, "php");
       
        //print hashtable
        System.out.println("Before delete Hash Table is ="+ht);
       
        //Clears this hashtable so that it contains no keys.
        ht.clear();
       
        System.out.println("After delete all element hashtable is = "+ht);
       
         }   
   
}

 Output:

 Before delete Hash Table is ={5=php, 4=c, 3=spring, 2=jersey, 1=java}

After delete all element hashtable is = {}

How to get entry set from Hashtable

import java.util.Hashtable;
import java.util.Map.Entry;
import java.util.Set;

public class HashtableEntrySet {
   
    public static void main(String[] args) {
       
        Hashtable<Integer,String> ht = new Hashtable<Integer,String>();
       
        /*
         * Maps the specified key to the specified
         * value in this hashtable
         */
        ht.put(1, "java");
        ht.put(2, "jersey");
        ht.put(3, "spring");
        ht.put(4, "c");
        ht.put(5, "php");
       
        //print hashtable
        System.out.println("Hash Table is ="+ht);
       
        //Returns a Set view of the mappings contained in this
        // map
        Set<Entry<Integer, String>> entry = ht.entrySet();
       
        for (Entry<Integer, String> ent : entry) {
            System.out.println(" key = "+ent.getKey()+" value = "+ent.getValue());
        }
    }   
   
}

Output:

Hash Table is ={5=php, 4=c, 3=spring, 2=jersey, 1=java}

key = 5 value = php

key = 4 value = c

key = 3 value = spring

key = 2 value = jersey

key = 1 value = java

How to get size of hashtable

import java.util.Hashtable;

public class HashTableKeyCount {
   
    public static void main(String[] args) {
       
        Hashtable<Integer,String> ht = new Hashtable<Integer,String>();
       
        /*
         * Maps the specified key to the specified
         * value in this hashtable
         */
        ht.put(1, "java");
        ht.put(2, "jersey");
        ht.put(3, "spring");
        ht.put(4, "c");
        ht.put(5, "php");
       
        //Returns the number of keys in this hashtable
       
        System.out.println("Hash Table size  ="+ht.size());
       
       
         }   

}

Output:

Hash Table size  =5

How to Free up RAM On Ubuntu/Debian

 Firstly  see ,how much memory is free on your system, open the Terminal and run this command:

free -m

I got this output:

Now run

sudo -i

echo 3 > /proc/sys/vm/drop_caches

Now ,Again run

free -m

How to get all keys of HashTable

import java.util.Hashtable;
import java.util.Set;

public class HashTableGetAllKeys {

    public static void main(String[] args) {
       
        Hashtable<Integer,String> ht = new Hashtable<Integer,String>();
       
        /*
         * Maps the specified key to the specified
         * value in this hashtable
         */
        ht.put(1, "java");
        ht.put(2, "jersey");
        ht.put(3, "spring");
        ht.put(4, "c");
        ht.put(5, "php");
       
        /*
         * Returns a Set view of the keys contained in this map.
         */
        Set<Integer> keys =ht.keySet();
       
        for (Integer key : keys) {
            System.out.println("key ="+key);
        }
   
    }
   
   
}


Output:

key =5

key =4

key =3

key =2

key =1

How to get value of key in HashTable

import java.util.Hashtable;

public class HashTableGetValueOfkey {
   
    public static void main(String[] args) {
       
        Hashtable<Integer,String> ht = new Hashtable<Integer,String>();
       
        /*
         * Maps the specified key to the specified
         * value in this hashtable
         */
        ht.put(1, "java");
        ht.put(2, "jersey");
        ht.put(3, "spring");
        ht.put(4, "c");
        ht.put(5, "php");
       
        System.out.println(" key = 1 and value ="+ht.get(1));
       
        System.out.println(" key = 2 and value ="+ht.get(2));
       
        System.out.println(" key = 9 and value ="+ht.get(9));
       
   
         }   

}

Output:

 key = 1 and value =java

 key = 2 and value =jersey

 key = 9 and value =null

How to Search Value in Hashtable Java

import java.util.Hashtable;

public class HashTableSearchValue {
   
    public static void main(String[] args) {
       
        Hashtable<Integer,String> ht = new Hashtable<Integer,String>();
       
        /*
         * Maps the specified key to the specified
         * value in this hashtable
         */
        ht.put(1, "java");
        ht.put(2, "jersey");
        ht.put(3, "spring");
        ht.put(4, "c");
        ht.put(5, "php");
       
        System.out.println(" value=java ="+ht.containsValue("java"));
        System.out.println(" value=ankush ="+ht.containsValue("ankush"));
        System.out.println(" value=java ="+ht.containsValue("java"));
       
    }   
}

Output:

 value=java =true

 value=ankush =false

 value=java =true

How to Search key in Hashtable Java

import java.util.Hashtable;

public class HashTableSearchKey {
   
    public static void main(String[] args) {
       
        Hashtable<Integer,String> ht = new Hashtable<Integer,String>();
       
        /*
         * Maps the specified key to the specified
         * value in this hashtable
         */
        ht.put(1, "java");
        ht.put(2, "jersey");
        ht.put(3, "spring");
        ht.put(4, "c");
        ht.put(5, "php");
       
         /*
          * Returns: true if and only if the specified object
          * is a key in this hashtable, as determined by the equals method;
             false otherwise.
          */
        System.out.println(" key =1   ="+ht.containsKey(1));
        System.out.println(" key =10   ="+ht.containsKey(10));
        System.out.println(" key =5   ="+ht.containsKey(5));
  }   

}





Output:


key =1   =true

key =10   =false

key =5   =true

How to iterate through Hashtable

import java.util.Hashtable;
import java.util.Set;

public class HashTableIterate {
   
    public static void main(String[] args) {
       
        Hashtable<Integer,String> ht = new Hashtable<Integer,String>();
       
        /*
         * Maps the specified key to the specified
         * value in this hashtable
         */
        ht.put(1, "java");
        ht.put(2, "jersey");
        ht.put(3, "spring");
        ht.put(4, "c");
        ht.put(5, "php");
       
        /*
         * Returns a Set view of the keys contained in this map.
         */
        Set<Integer> keys =ht.keySet();
       
        for (Integer key : keys) {
            System.out.println(" key = "+key+" value ="+ht.get(key));
        }
    }   
}

Output:

 key = 5 value =php

 key = 4 value =c

 key = 3 value =spring

 key = 2 value =jersey

 key = 1 value =java

How to storing Java Object In HashTable

import java.util.Hashtable;
import java.util.Set;

public class HashTableOfObject {

    public static void main(String[] args) {

        Hashtable<Integer,User> ht = new Hashtable<Integer,User>();
       
        ht.put(1,new User("ankush",100));
        ht.put(2,new User("shivam",200));
        ht.put(3,new User("raja", 500));
        ht.put(5,new User("ram",900));
        ht.put(6,new User("ravi",750));

        /*
         * Returns a Set view of the keys contained in this map.
         */
        Set<Integer> keys =ht.keySet();
       
        for (Integer key : keys) {
           
            /*
             * Returns the value to which the
             * specified key is  mapped, or null if
             *  this map contains no mapping for the key.
             */
            User user = ht.get(key);
            System.out.println(" key ="+key+" id ="+user.getId()+" name ="+user.getName());
        }

       
    }
}

class User {
    private String name;
    private int id;

    public User(String name, int id) {
        super();
        this.name = name;
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

}

Output:

 key =6 id =750 name =ravi

 key =5 id =900 name =ram

 key =3 id =500 name =raja

 key =2 id =200 name =shivam

 key =1 id =100 name =ankush

How to create HashTable In Java

import java.util.Hashtable;

public class CreateHashTable {
   
public static void main(String[] args) {
   
    Hashtable<Integer,String> ht = new Hashtable<Integer,String>();
   
    /*
     * Maps the specified key to the specified
     * value in this hashtable
     */
    ht.put(1, "java");
    ht.put(2, "jersey");
    ht.put(3, "spring");
    ht.put(4, "c");
    ht.put(5, "php");
   
    //print hashtable
    System.out.println("Hash Table is ="+ht);
     }   
}

Output:

Hash Table is ={5=php, 4=c, 3=spring, 2=jersey, 1=java}

Select Data From Cassandra Using Java

import com.datastax.driver.core.Cluster;
import com.datastax.driver.core.ResultSet;
import com.datastax.driver.core.Row;
import com.datastax.driver.core.Session;

public class SelectFromCassandra {
    public static void main(String[] args) {

        Cluster cluster = Cluster.builder().addContactPoint("127.0.0.1").build();
        Session session = cluster.connect("demo");
       
        ResultSet rs = session.execute("SELECT *FROM emp1 WHERE emp_id=500");
        for (Row row : rs) {
            System.out.println("emp_id = "+row.getInt("emp_id")+" name = "+row.getString("name"));
        }
    }

}

Insert Data Into Cassandra Example Set 2

import com.datastax.driver.core.BoundStatement;
import com.datastax.driver.core.Cluster;
import com.datastax.driver.core.PreparedStatement;
import com.datastax.driver.core.Session;

public class CassandraExample {
   
    public static void main(String[] args) {
       
        Cluster cluster = Cluster.builder().addContactPoint("127.0.0.1").build();
       
        Session session = cluster.connect("demo");
       
        PreparedStatement ps = session.prepare
                ("insert into emp1(emp_id,ss_id,name) values(?,?,?)");
       
        BoundStatement bs = new BoundStatement(ps);
       
        session.execute(bs.bind(255,320,"javaproficiency"));

        System.out.println("ok");
       
    }
}

Insert Data Into Cassandra Example

import com.datastax.driver.core.Cluster;
import com.datastax.driver.core.Session;






Connect return cassandra connection

public class Connect {

    public static Session getConection(){
       
        Cluster cluster = Cluster.builder().addContactPoint("127.0.0.1").build();

        Session session = cluster.connect("demo");

        return session;

    }
   
}

In test class we will insert data into cassandra database

import com.datastax.driver.core.Session;

public class Test {

    public static void main(String[] args) {

        Session session = Connect.getConection();
        String query = "insert into emp1(emp_id,ss_id,name) values(500,205,'raja')";
        session.execute(query);
        System.out.println("ok");
    }
}

Java Hashtable Examples

How to create HashTable In Java

How to iterate through Hashtable

How to storing Java Object In HashTable

How to Search key in Hashtable Java

How to Search Value in Hashtable Java 

How to get value of key in HashTable

How to get all keys of HashTable

How to get size of hashtable

How to get entry set from Hashtable

How to delete all elements from Hashtable

How to get elements using Enumeration from Hashtable

How to create shallow copy of Hashtable

 

How to check TreeSet Empty Or not

import java.util.Set;
import java.util.TreeSet;

public class IsEmpty {
   
    public static void main(String[] args) {
       
           Set<String> ts = new TreeSet<String>();
            ts.add("mumbai");
            ts.add("delhi");
            ts.add("kolkata");
            ts.add("chandigarh");
            ts.add("dehradun");

            // print treeset
            System.out.println(" ts ="+ts);
           
            System.out.println("Is Empty = "+ts.isEmpty());
           
            Set<String> set = new TreeSet<String>();
           
            System.out.println("Is Empty = "+set.isEmpty());
       
        }

}



Output:

ts =[chandigarh, dehradun, delhi, kolkata, mumbai]

Is Empty = false

Is Empty = true

Related Posts: 

How to create TreeSet In Java

How to Convert a TreeSet to ArrayList

How to convert array to TreeSet

How to sort TreeSet with user defined objects.

How to copy all element of a Treeset to other 

How To Remove Element of Treeset 

How to remove all element from TreeSet

How to Remove Set From TreeSet 

How To Convert Treeset To Array 

How to find does TreeSet contains elements or not 

How to count number of element in TreeSet

How to check TreeSet Empty Or not

How to count number of element in TreeSet

import java.util.Set;
import java.util.TreeSet;

public class CountElement {
   
    public static void main(String[] args) {
       
           Set<String> ts = new TreeSet<String>();
            ts.add("mumbai");
            ts.add("delhi");
            ts.add("kolkata");
            ts.add("chandigarh");
            ts.add("dehradun");

            // print treeset
            System.out.println(" ts ="+ts);
           
            /*
             * Returns the number of elements in this set (its
                cardinality). If this set contains more than
                Integer.MAX_VALUE elements, returns
                Integer.MAX_VALUE.
             */
           
            System.out.println("Size of treeset = "+ts.size());
       
        }

}



Output:

 ts =[chandigarh, dehradun, delhi, kolkata, mumbai]

Size of treeset = 5

Related Posts: 

How to create TreeSet In Java

How to Convert a TreeSet to ArrayList

How to convert array to TreeSet

How to sort TreeSet with user defined objects.

How to copy all element of a Treeset to other 

How To Remove Element of Treeset 

How to remove all element from TreeSet

How to Remove Set From TreeSet 

How To Convert Treeset To Array 

How to find does TreeSet contains elements or not 

How to count number of element in TreeSet

How to check TreeSet Empty Or not

How to find does TreeSet contains elements or not

Returns true if this set contains the specified element.More formally, returns true if and only if this set contains an element e such that (o==null ? e==null :
 o.equals(e)).


import java.util.Set;
import java.util.TreeSet;

public class ContailsElement {
   
    public static void main(String[] args) {
       
           Set<String> ts = new TreeSet<String>();
            ts.add("mumbai");
            ts.add("delhi");
            ts.add("kolkata");
            ts.add("chandigarh");
            ts.add("dehradun");

            // print treeset
            System.out.println(" ts ="+ts);
           
            System.out.println(ts.contains("java"));
            System.out.println(ts.contains("delhi"));
            System.out.println(ts.contains("php"));
       
        }

}

Output:

ts =[chandigarh, dehradun, delhi, kolkata, mumbai]

false

true

false

Related Posts: 

How to create TreeSet In Java

How to Convert a TreeSet to ArrayList

How to convert array to TreeSet

How to sort TreeSet with user defined objects.

How to copy all element of a Treeset to other 

How To Remove Element of Treeset 

How to remove all element from TreeSet

How to Remove Set From TreeSet 

How To Convert Treeset To Array 

How to find does TreeSet contains elements or not 

How to count number of element in TreeSet

How to check TreeSet Empty Or not

How To Convert Treeset To Array

import java.util.Set;
import java.util.TreeSet;

public class TreeSetToArray {
   
    public static void main(String[] args) {
       
           Set<String> ts = new TreeSet<String>();
            ts.add("mumbai");
            ts.add("delhi");
            ts.add("kolkata");
            ts.add("chandigarh");
            ts.add("dehradun");

            // print treeset
            System.out.println("tree set is ="+ts);
           
            String [] arr = new  String[ts.size()];
       
            /*
             * Returns an array containing all of
             * the elements in this set
             */
           
            ts.toArray(arr);
       
            System.out.println("Print Array Element ");
           
            for (String str : arr) {
                 System.out.println("Array Element is = "+str);   
            }
   
    }
   

}




Output:



tree set is =[chandigarh, dehradun, delhi, kolkata, mumbai]

Print Array Element

Array Element is = chandigarh

Array Element is = dehradun

Array Element is = delhi

Array Element is = kolkata

Array Element is = mumbai

Related Posts: 

How to create TreeSet In Java

How to Convert a TreeSet to ArrayList

How to convert array to TreeSet

How to sort TreeSet with user defined objects.

How to copy all element of a Treeset to other 

How To Remove Element of Treeset 

How to remove all element from TreeSet

How to Remove Set From TreeSet 

How To Convert Treeset To Array 

How to find does TreeSet contains elements or not 

How to count number of element in TreeSet

How to check TreeSet Empty Or not