Wednesday, 25 November 2015

How to Check number is prime or not


A number which is divided by one and itself is called prime number. For Example

7 is a prime number and
8 is not a prime number

package com.javaproficiency;

public class PrintPrime {

public static void main(String[] args) {
int i =101;
boolean flag = false;
for(int j=2 ; j <= i/2; j++){
if(i%j==0)
{
flag = true ;
break;
}
}
if(flag){
System.out.println(" number "+ i +" is not prime");
}else{
System.out.println(" number "+ i +" is  prime");
}

}

}


Output :

 number 101 is  prime

How to print array without using loop in java

How to print array without using loop in java is frequently asked question in interview. We can print array without using any loop. For this purpose we will use Arrays's method toString().

package com.javaproficiency;

import java.util.Arrays;

public class PrintArray {
//print array without using loop in java
public static void main(String[] args) {

int [] arr = {15,60,32,33,12};
System.out.println(" Print array ="+ Arrays.toString(arr));

char [] crr = {'A','B','C','D','E','F'};

System.out.println(" Print Array ="+ Arrays.toString(crr));

}

}


Output:

 Print array =[15, 60, 32, 33, 12]
 Print Array =[A, B, C, D, E, F]

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

package com.javaproficiency;

public class LargestElement {
//How to find largest element in an array with index and value ?

public static void main(String[] args) {

int [] arr ={4,5,10,12,8,6};
int largest =0;
int index =0;
for(int i =0 ; i < arr.length; i++){
if( largest < arr[i]){
largest = arr[i];
index = i;
}
}
System.out.println(" largest element  ="+ largest + " index ="+index);

}

}

Output :

 largest element  =12 index =3

Program For nth Fibonacci Number in Java

The Fibonacci numbers are the numbers in the following integer sequence.

0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 141, ……..

In simple word such series that each element is sum of two previous element is called Fibonacci series.

In mathematical terms, the sequence Fn of Fibonacci numbers is defined by the recurrence relation

    Fn = Fn-1 + Fn-2

1. Program to print Fibonacci Series without using Recursion In Java



package com.javaproficiency;

public class Fibonacciseries {
public static void main(String[] args) {
//Fibonacci series without using Recursive?
int n=10;
int x = 1;
int y = 0;
int z =0;
System.out.print(y +" "+ x);
int i=0;
while(i < n){
z=y+x;
System.out.print("  "+ z);
y=x;
x=z;
i++;
}

}

}


output :

0 1  1  2  3  5  8  13  21  34  55  89


2. Program to print Fibonacci Series using Recursion In Java 



package com.javaproficiency;

public class Fibonacciserieswithrecursion {

    public static void main(String[] args) {
int n = 10;
int a =0 ;
int b =1;
System.out.print( a + " " + b);
fibonaci(n, a, b);
}
   
    static void fibonaci(int n , int a ,int b){
    int sum = 0;
    if (n > 0 ) {
    sum = a+b;
    a = b;
    b = sum;
System.out.print(" "+ sum);
    fibonaci(n-1, a, b);
}
   
   
    }

}


output:

0 1 1 2 3 5 8 13 21 34 55 89

Monday, 23 November 2015

Activator Eclipse Command is not working In PlayFramwork

When i run 


activator eclipse

command then i get following error.

[info] Set current project to demo (in build file:/home/anuj/playapp/demo/)
[error] Not a valid command: eclipse (similar: help, alias)
[error] Not a valid project ID: eclipse
[error] Expected ':' (if selecting a configuration)
[error] Not a valid key: eclipse (similar: deliver, licenses, clean)
[error] eclipse
[error]        ^

How can i import scala project to eclipse ?

I run this command for scala project import to eclipse . But when i run activator eclipse command , i get error.

Solution:

Go to project folder inside your project and Append this below to your plugins.sbt file:

addSbtPlugin("com.typesafe.sbteclipse" % "sbteclipse-plugin" % "4.0.0")

now run again

activator eclipse command and you will run this command now successfully. After that you can import this project to eclipse.





Saturday, 21 November 2015

java.lang.UnsupportedClassVersionError: com/typesafe/config/ConfigException : Unsupported major.minor version 52.0

java.lang.UnsupportedClassVersionError: com/typesafe/config/ConfigException : Unsupported major.minor version 52.0
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
    at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
    at com.typesafe.sbt.web.SbtWeb$$anonfun$com$typesafe$sbt$web$SbtWeb$$load$1.apply(SbtWeb.scala:535)
    at com.typesafe.sbt.web.SbtWeb$$anonfun$com$typesafe$sbt$web$SbtWeb$$load$1.apply(SbtWeb.scala:535)
    at scala.Option.fold(Option.scala:157)
    at com.typesafe.sbt.web.SbtWeb$.com$typesafe$sbt$web$SbtWeb$$load(SbtWeb.scala:549)
    at com.typesafe.sbt.web.SbtWeb$$anonfun$globalSettings$1$$anonfun$apply$1.apply(SbtWeb.scala:143)
    at com.typesafe.sbt.web.SbtWeb$$anonfun$globalSettings$1$$anonfun$apply$1.apply(SbtWeb.scala:143)
    at scala.Function1$$anonfun$andThen$1.apply(Function1.scala:55)
    at sbt.Project$.setProject(Project.scala:319)
    at sbt.BuiltinCommands$.doLoadProject(Main.scala:484)
    at sbt.BuiltinCommands$$anonfun$loadProjectImpl$2.apply(Main.scala:475)
    at sbt.BuiltinCommands$$anonfun$loadProjectImpl$2.apply(Main.scala:475)
    at sbt.Command$$anonfun$applyEffect$1$$anonfun$apply$2.apply(Command.scala:58)
    at sbt.Command$$anonfun$applyEffect$1$$anonfun$apply$2.apply(Command.scala:58)
    at sbt.Command$$anonfun$applyEffect$2$$anonfun$apply$3.apply(Command.scala:60)
    at sbt.Command$$anonfun$applyEffect$2$$anonfun$apply$3.apply(Command.scala:60)
    at sbt.Command$.process(Command.scala:92)
    at sbt.MainLoop$$anonfun$1$$anonfun$apply$1.apply(MainLoop.scala:98)
    at sbt.MainLoop$$anonfun$1$$anonfun$apply$1.apply(MainLoop.scala:98)
    at sbt.State$$anon$1.process(State.scala:184)
    at sbt.MainLoop$$anonfun$1.apply(MainLoop.scala:98)
    at sbt.MainLoop$$anonfun$1.apply(MainLoop.scala:98)
    at sbt.ErrorHandling$.wideConvert(ErrorHandling.scala:17)
    at sbt.MainLoop$.next(MainLoop.scala:98)
    at sbt.MainLoop$.run(MainLoop.scala:91)
    at sbt.MainLoop$$anonfun$runWithNewLog$1.apply(MainLoop.scala:70)
    at sbt.MainLoop$$anonfun$runWithNewLog$1.apply(MainLoop.scala:65)
    at sbt.Using.apply(Using.scala:24)
    at sbt.MainLoop$.runWithNewLog(MainLoop.scala:65)
    at sbt.MainLoop$.runAndClearLast(MainLoop.scala:48)
    at sbt.MainLoop$.runLoggedLoop(MainLoop.scala:32)
    at sbt.MainLoop$.runLogged(MainLoop.scala:24)
    at sbt.StandardMain$.runManaged(Main.scala:53)
    at sbt.xMain.run(Main.scala:28)
    at xsbt.boot.Launch$$anonfun$run$1.apply(Launch.scala:109)
    at xsbt.boot.Launch$.withContextLoader(Launch.scala:128)
    at xsbt.boot.Launch$.run(Launch.scala:109)
    at xsbt.boot.Launch$$anonfun$apply$1.apply(Launch.scala:35)
    at xsbt.boot.Launch$.launch(Launch.scala:117)
    at xsbt.boot.Launch$.apply(Launch.scala:18)
    at xsbt.boot.Boot$.runImpl(Boot.scala:41)
    at xsbt.boot.Boot$.main(Boot.scala:17)
    at xsbt.boot.Boot.main(Boot.scala)
[error] java.lang.UnsupportedClassVersionError: com/typesafe/config/ConfigException : Unsupported major.minor version 52.0
[error] Use 'last' for the full log.

solution:

Still you are using java7. You can download java8. If you already install java8 make sure it is active.You can change java version using bellow commands.

How To Change Java Version 

 

$ sudo update-alternatives --config java

There are 2 choices for the alternative java (providing /usr/bin/java).

  Selection    Path                                            Priority   Status
------------------------------------------------------------
* 0            /usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java   1061      auto mode
  1            /usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java   1061      manual mode
  2            /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java   1051      manual mode

Press enter to keep the current choice[*], or type selection number: 2

update-alternatives: using /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java
to provide /usr/bin/java (java) in manual mode
 
 Now you can check you java version using below command

java -version




Thursday, 19 November 2015

How to sort a TreeSet with user defined objects In Java


TreeSet have element in their natural ordering. If we make a TreeSet of Sting it have elements in alphabetical ascending order visit example here . If we want to own sorting with TreeSet on user defined objects , have to pass Comparator object along with TreeSet constructor call. The Comparator implementation holds the sorting logic. You have to override compare() method to provide the sorting logic on user defined objects. I have given examples sorted TreeSet of user defined object based on String(name) and Integer(rollNo).

package com.treesetsort;

import java.util.Comparator;
import java.util.TreeSet;

public class TreeSetSort {
public static void main(String[] args) {
TreeSet<Stu> nameSort = new TreeSet<Stu>( new StuNameComp());
nameSort.add(new Stu("yogesh", 10));
nameSort.add(new Stu("shivam", 50));
nameSort.add(new Stu("amit", 30));
nameSort.add(new Stu("pankaj", 35));
System.out.println("printed sorted treeset base on name of student type object");
for (Stu stu : nameSort) {
System.out.println("name ="+ stu.getName()+ " roll No ="+ stu.getRollNo());
}
System.out.println("+++++++++++++++++");
TreeSet<Stu> rollNoSort = new TreeSet<Stu>( new StuRollComp());
rollNoSort.add(new Stu("yogesh", 10));
rollNoSort.add(new Stu("shivam", 50));
rollNoSort.add(new Stu("amit", 30));
rollNoSort.add(new Stu("pankaj", 35));

System.out.println("printed sorted treeset based on roll no of student type object");
for (Stu stu : rollNoSort) {
System.out.println("name ="+ stu.getName()+ " roll No ="+ stu.getRollNo());
}
}
}

class StuNameComp implements Comparator<Stu>{
@Override
public int compare(Stu s1, Stu s2) {
return s1.getName().compareTo(s2.getName());
}
}
class StuRollComp implements Comparator<Stu>{

@Override
public int compare(Stu s1, Stu s2) {
if(s1.getRollNo() > s2.getRollNo()){
return 1;
} else {
return -1;
}
}
}

class Stu {
private String name;
private int rollNo;
public Stu(String name, int rollNo) {
super();
this.name = name;
this.rollNo = rollNo;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getRollNo() {
return rollNo;
}
public void setRollNo(int rollNo) {
this.rollNo = rollNo;
}
}



Output:

printed sorted treeset base on name of student type object
name =amit roll No =30
name =pankaj roll No =35
name =shivam roll No =50
name =yogesh roll No =10

+++++++++++++++++

printed sorted treeset based on roll no of student type object
name =yogesh roll No =10
name =amit roll No =30
name =pankaj roll No =35
name =shivam roll No =50



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