Method Overriding Example - Java Program

package com.javaproficiency;


class Y {

void display(){
System.out.println(" Y is called");
}

}


public class X extends Y{

void display(){
System.out.println(" X is called");
}


public static void main(String[] args) {

    Y y = new Y();
    X x = new X();
    Y obj = new X();
   
    y.display();
    x.display();
    obj.display();
   
   

}

}

Output:

 Y is called

 X is called

 X is called

How to Find Common Element In Two arrays - java program

package com.javaproficiency;

public class CommonElementOfTwoArray {

public static void main(String[] args) {

  int []arr = {10,15,20,25,40};
       int []brr ={5,18,20,25,30,10};
     
       for( int i=0 ; i < arr.length ; i++ ){
            for( int j=0 ; j < brr.length ; j++  ){
                if(arr[i] == brr[j])
                    System.out.println(arr[i]);
            }
       }

}

}

Output:

10

20

25

Top 50 Core Java Coding / Programming Questions And Answers : Technical Interview In Java

If you want to be a developer when you can faced a technical round in your interview.Most of the student feel it hard round. But if you prepare in a right path, then you can clear your technical round easily.Most of student try to preparation  hardest technical interview question firstly. But some basic questions play a good roll in interviews. As my experience , I will share top core java  coding questions with answer. I hope , these question may be more helpful for all.

Program For nth Fibonacci Number in Java

How to find largest element in an array with index and value 

How to print array without using loop in java

Check number even or odd without using modulo operator

HCF and LCM of two number

Find duplicate charcters with occurrences in a string

Reverse string in java

Swap two number using bit operator

How to count the number of occurrences of a character in a string in java

How to print numbers from 1 to 10 without using loop?

How to Sort the String using string Method In java

Object Cloning in java example?

How to Make Singleton Class In Java

How to reverse a number in java

How to Check number is prime or not

How to count the number of occurrences of a character in a string in java

Count the number of occurrences of a character in a string is good programming questions . It is ask in colleges and schools mostly. This question also asked in many times in interviews. 

Method 1:

We can count number of occurrences of a character in a string with the help of indexOf() method.

package com.javaproficiency;

public class CountCharOccurance {

public static void main(String[] args) {

String str = "javaproficiencyexamplebyannu";

 

    String findStr = "a";

    int lastIndex = 0;

    int counter = 0;

 

    while (lastIndex != -1) {

 

     lastIndex = str.indexOf(findStr, lastIndex);

 

     if (lastIndex != -1) {

      counter++;

      lastIndex += findStr.length();

 

     }

    }

    System.out.println(counter);

}

}

Output: 

4

Method 2:

In this example we will use charAt() method of string for count number of occurrences of a character in a string .

package com.javaproficiency;

public class CountCharOccurancejava {

public static void main(String[] args) {

String s = "javaproficiencyexamplebyannu";

int counter = 0;

for( int i=0; i<s.length(); i++ ) {

   if( s.charAt(i) == 'a' ) {

       counter++;

   } 

}

System.out.println( counter );

}

}

Output:

4

How to print numbers from 1 to 10 without using loop?

We can print numbers 1 to 10 or 1 to 100 using recursion. Recursion is a good alternatives of loop. There we can use recursion to print numbers 1 to 10. We also use goto statement but in java we can not used goto statement. visit java keyword list http://docs.oracle.com/javase/tutorial/java/nutsandbolts/_keywords.html. So we will use here recursion.


package com.javaproficiency;

public class PrintNumber {

public static void main(String[] args) {

printNumberWithRecursion(1);

}

public static void printNumberWithRecursion(int n){

if (n <= 10) {
System.out.println(" number is ="+ n);
printNumberWithRecursion(n+1);
}

}

}

Output :

 number is =1

 number is =2

 number is =3

 number is =4

 number is =5

 number is =6

 number is =7

 number is =8

 number is =9

 number is =10

How to Sort the String using string Method In java

Java have a lot of method for string operations. We can sort a string by convert in to array of characters , now we will sort array after that we will make a new string from sorted array.Now our new string is in sorted order of characters.

package com.javaproficiency;

import java.util.Arrays;

public class StringSort {

public static void main(String[] args) {
String str = "xyabds";
char [] arr = str.toCharArray();
Arrays.sort(arr);
String sortedStr = new String(arr);
System.out.println(" sorted string = "+sortedStr);
}

}

Output:

 sorted string = abdsxy

Object Cloning in java example?

package com.javaproficiency;

public class Emp implements Cloneable {
//Object Cloning in java example?

int id;
String name;

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

public Emp clone() throws CloneNotSupportedException{

return (Emp ) super.clone();

}

public static void main(String[] args) {

Emp  emp = new Emp(10, "java");
Emp emp1 = null;
try {
emp1 = emp.clone();
} catch (CloneNotSupportedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

System.out.println(" clone object is ");
System.out.println("id ="+ emp1.id+ " name ="+ emp1.name);

}

}


Output:

 clone object is
 id =10 name =java