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Java Programs

Swap two numbers without using third variable

Posted by: Instanceofjava Posted date: December 19, 2015 / comment : 3 Java Programs

1. Java Interview Program to Swap two numbers without using third variable in java

package com.instaceofjava;
public class SwapTwoNumbers {
public static void main(String[] args) {
int number1=20;
int number2=30;
System.out.println("Before Swapping");
System.out.println("Value of number1 is :" + number1);
System.out.println("Value of number2 is :" +number2);
number1=number1+number2;
number2=number1-number2;
number1=number1-number2;
System.out.println("After Swapping");
System.out.println("Value of number1 is :" + number1);
System.out.println("Value of number2 is :" +number2);
}
}

Output:

Before Swapping
Value of number1 is :20
Value of number2 is :30
After Swapping
Value of number1 is :30
Value of number2 is :20

2. Java Program to Swap two numbers by using division and multiplication.

package com.instaceofjava;
public class SwapTwoNumbers {
public static void main(String[] args) {
int number1=20;
int number2=30;
System.out.println("Before Swapping");
System.out.println("Value of number1 is :" + number1);
System.out.println("Value of number2 is :" +number2);
number1=number1*number2;
number2=number1/number2;
number1=number1/number2;
System.out.println("After Swapping");
System.out.println("Value of number1 is :" + number1);
System.out.println("Value of number2 is :" +number2);
}
}

Output:

Before Swapping
Value of number1 is :20
Value of number2 is :30
After Swapping
Value of number1 is :30
Value of number2 is :20

3. Java Program to Swap two integers by using bit wise operators

package com.instaceofjava;
public class SwapTwoNumbers {
public static void main(String[] args) {
int number1=2;
int number2=4;
System.out.println("Before Swapping");
System.out.println("Value of number1 is :" + number1);
System.out.println("Value of number2 is :" +number2);
number1=number1^number2;
number2=number1^number2;
number1=number1^number2;
System.out.println("After Swapping");
System.out.println("Value of number1 is :" + number1);
System.out.println("Value of number2 is :" +number2);
}
}

Output:

Before Swapping
Value of number1 is :2
Value of number2 is :4
After Swapping
Value of number1 is :4
Value of number2 is :2

Reverse words in a String

Posted by: Instanceofjava Posted date: November 10, 2015 / comment : 0 Java Programs

1. Java Interview Program to Reverse words in a string

package com.instaceofjava;
public class ReverseString {
public static void main(String[] args) {
String strng= "Instance of Java ";
String str[] =strng.split(" ");
String result="";
for(int i=str.length()-1;i>=0;i--){
result += str[i]+" ";
}
System.out.println(result );
}
}

Output:

Java of Instance

2. Java Interview Program to Reverse words in a string

package com.instaceofjava;
public class ReverseString {
public static void main(String[] args) {
String strng= "Instance of Java ";
StringBuilder sb = new StringBuilder(strng.length() + 1);
String[] words = strng.split(" ");
for (int i = words.length - 1; i >= 0; i--) {
sb.append(words[i]).append(' ');
}
sb.setLength(sb.length() - 1);
String result= sb.toString();
System.out.println(result);
}
}

Output:

Java of Instance

Program Check even or odd without using modulus and division operators

Posted by: Instanceofjava Posted date: March 02, 2015 / comment : 9 Java Programs

write a progrma to check number is even or odd without using modulus or divition

Checking the number even or odd program is very easy. Anybody can solve this but there is a condition we need to see.
When we get this question in interview "write a program to check given number is even or odd" always continues with "without using modulus and division operators".
Before going to actual program lets see how to check a number is even or odd by using modulus and division operators.

Program to check number is even or odd by using modulus "%" operator

package instanceofjava;
import java.util.Scanner;
public class EvenorOdd {
public static void main(String []args ) {
int number;
Scanner in= new Scanner(System.in);
System.out.println("Enter a number to check even or odd");
number=in.nextInt();
if((number % 2)==0){
System.out.println(+number+" is Even number");
}else{
System.out.println(+number+" is Odd Number");
}
}
}

Output:

Enter a number to check even or odd
37
37 is Odd Number

Program to check number is even or odd by using division "/" operator

package instanceofjava;
import java.util.Scanner;
public class EvenorOdd {
public static void main(String []args ) {
int number;
Scanner in= new Scanner(System.in);
System.out.println("Enter a number to check even or odd");
number=in.nextInt();
if((number / 2)*2==number){
System.out.println(+number+" is Even number");
}else{
System.out.println(+number+" is Odd Number");
}
}
}

Output:

Enter a number to check even or odd
46
46 is Even Number

Without using modulus and division operators:

The above two programs will check number is even or odd and displays result.
Now we need to write a program to check even or odd without using modulus and division operators.
It is very simple if you know about operators including "BIT WISE".
Yes using Bit Wise AND "&" operator we can check a number is even or odd.
Before starting our program lets see how this bit wise AND "&" operator will work.

Bitwise Operators :

Bit wise operators will work on bits at a time.
AND : 1 & 1=1
OR : 0 | 1= 1 , 1 | 0=1 , 1| 1= 1
XOR: 0 ^ 1= 1 , 1^ 0=1
NOT : !0=1

Take two number 2 and 3
010 : 2
011 : 3
------
010 : 2
------
Take two numbers 2 and 1
010 :2
001 :1
-----
000 :0
-----

From above example we can say that on every even number & 1 gives 0.
So this is our logic to be implemented in our program if "Number & 1==0" then its even number.

Program to check number is even or odd by using "&" operator

package instanceofjava;
import java.util.Scanner;
public class EvenorOdd {
public static void main(String []args ) {
int number;
Scanner in= new Scanner(System.in);
System.out.println("Enter a number to check even or odd");
number=in.nextInt();
if((number & 1)==0){
System.out.println(+number+" is Even number");
}else{
System.out.println(+number+" is Odd Number");
}
}
}

Output:

Enter a number to check even or odd
9
9 is Odd Number

Using Shift Operators:

We can check even or odd by using shift operators also may be it is not a better solution but trying to cover alternative.
Lets see how shift operators will work
Lets do this 2 >> 1
2 means 010 so now we need to shift right side by 1 place
010
-----
001
Here we added one "0" to the left side to shift right
So the value became 1
Now will try left shift 001 >> 1
001
----
010
010<<1=001(1) and 001 >> 001=010(2)
By this we can say if a (number >>1)<<1 gives same then that is even number. result=input
Lets check for odd number 3
011>>1=001 which is 1 and 001<<1=010 which is 2 so (3>>1)>>1=2 so result!=input

Program to check number is even or odd by using Shift operator

package instanceofjava;
import java.util.Scanner;
public class EvenorOdd {
public static void main(String []args ) {
int number;
Scanner in= new Scanner(System.in);
System.out.println("Enter a number to check even or odd");
number=in.nextInt();
if( ( number >> 1) <<1==number){
System.out.println(+number+" is Even number");
}else{
System.out.println(+number+" is Odd Number");
}
}
}

Output:

Enter a number to check even or odd
64
64 is Even Number

Here is the another solution for this.

package instanceofjava;
import java.util.Scanner;
class EvenOrOddDemo
{
public static void main(String[] args)
{
Scanner sc=new Scanner(System.in);
System.out.println("Enter a number to check whether it is even or odd without using Modulus
and Division: ");
int n=Integer.parseInt(sc.next());
float f=(float)n/(float)2;
int d=(int)f*2;
if(d==n)
System.out.println(n+" is a even number");
else
System.out.println(n+" is a odd number");
}
}

Output:

Enter a number to check whether it is even or odd without using Modulus and Division
4
4 is Even Number

Multiply two matrices

Posted by: Instanceofjava Posted date: January 24, 2015 / comment : 0 Java Programs

package com.instanceofjava;
import java.util.Scanner;
class Multiply2Matrices{
public static void main(String args[])
{
int m, n, p, q, sum = 0, c, d, k;
Scanner in = new Scanner(System.in);
System.out.println("Enter the number of rows and columns of first matrix");
m = in.nextInt();
n = in.nextInt();
int first[][] = new int[m][n];
System.out.println("Enter the elements of first matrix");
for ( c = 0 ; c < m ; c++ )
for ( d = 0 ; d < n ; d++ )
first[c][d] = in.nextInt();
System.out.println("Enter the number of rows and columns of second matrix");
p = in.nextInt();
q = in.nextInt();
if ( n != p )
System.out.println("Matrices with entered orders can't be multiplied with each other.");
else
{
int second[][] = new int[p][q];
int multiply[][] = new int[m][q];
System.out.println("Enter the elements of second matrix");
for ( c = 0 ; c < p ; c++ )
for ( d = 0 ; d < q ; d++ )
second[c][d] = in.nextInt();
for ( c = 0 ; c < m ; c++ )
{
for ( d = 0 ; d < q ; d++ )
{
for ( k = 0 ; k < p ; k++ )
{
sum = sum + first[c][k]*second[k][d];
}
multiply[c][d] = sum;
sum = 0;
}
}
System.out.println("Multiplication of entered matrices:-");
for ( c = 0 ; c < m ; c++ )
{
for ( d = 0 ; d < q ; d++ )
System.out.print(multiply[c][d]+"\t");
System.out.print("\n");
}
}
}
}

OutPut:

Enter the number of rows and columns of first matrix
2 2
Enter the elements of first matrix
2 2
2 3
Enter the number of rows and columns of second matrix
2 2
Enter the elements of second matrix
1 1
1 1
Multiplication of entered matrices:-
4 4
5 5

add two matrices

Posted by: Instanceofjava Posted date: January 24, 2015 / comment : 0 Java Programs

package com.instanceofjava;
import java.util.Scanner;
class Add2Matrix
{
public static void main(String args[])
{
int rows, cols, c, d;
Scanner in = new Scanner(System.in);
System.out.println("Please Enter number of rows and columns");
rows = in.nextInt();
cols = in.nextInt();
int first[][] = new int[rows][cols];
int second[][] = new int[rows][cols];
int sum[][] = new int[rows][cols];
System.out.println("Please Enter elements of first matrix");
for ( c = 0 ; c < rows ; c++ )
for ( d = 0 ; d < cols ; d++ )
first[c][d] = in.nextInt();
System.out.println("Please Enter elements of second matrix");
for ( c = 0 ; c < rows ; c++ )
for ( d = 0 ; d < cols ; d++ )
second[c][d] = in.nextInt();
for ( c = 0 ; c < rows ; c++ )
for ( d = 0 ; d < cols ; d++ )
sum[c][d] = first[c][d] + second[c][d]; //replace '+' with '-' to subtract matrices
System.out.println("Sum of entered matrices:-");
for ( c = 0 ; c < rows ; c++ )
{
for ( d = 0 ; d < cols ; d++ )
System.out.print(sum[c][d]+"\t");
System.out.println();
}
}
}

Output:

Please Enter number of rows and columns
3
3
Please Enter elements of first matrix
1 1 1
1 1 1
1 1 1
Please Enter elements of second matrix
2 2 2
2 2 2
2 2 2
Sum of entered matrices:-
3 3 3
3 3 3
3 3 3

Sort ArrayList in descending order

Posted by: Instanceofjava Posted date: January 06, 2015 / comment : 0 Java Programs

Descending order:

package com.instanceofjavaforus;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
public class SortArrayListDesc {
public static void main(String[] args) {
//create an ArrayList object
ArrayList arrayList = new ArrayList();
//Add elements to Arraylist
arrayList.add(1);
arrayList.add(2);
arrayList.add(3);
arrayList.add(4);
arrayList.add(5);
arrayList.add(6);
/*
Use static Comparator reverseOrder() method of Collections
utility class to get comparator object
*/
Comparator comparator = Collections.reverseOrder();
System.out.println("Before sorting : " + arrayList);
/*
use
static void sort(List list, Comparator com) method of Collections class.
*/
Collections.sort(arrayList,comparator);
System.out.println("After sorting : + arrayList);
}
}

OutPut:
Before sorting : [1, 2, 3, 4, 5, 6]
After sorting : [6, 5, 4, 3, 2, 1]

Ascending order:

package com.instanceofjavaforus;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
public class SortArrayListAsc{
public static void main(String[] args) {
//create an ArrayList object
ArrayList arrayList = new ArrayList();
//Add elements to Arraylist
arrayList.add(10);
arrayList.add(4);
arrayList.add(7);
arrayList.add(2);
arrayList.add(5);
arrayList.add(3);
System.out.println("Before sorting : " + arrayList);
/*
use
static void sort(List list) method of Collections class.
*/
Collections.sort(arrayList);
System.out.println("After sorting : + arrayList);
}
}

OutPut:
Before sorting : [10, 4, 7, 2, 5, 3]
After sorting : [2, 3, 4, 5, 7, 10]

Arraylist add element at specific index

Posted by: Instanceofjava Posted date: January 05, 2015 / comment : 0 Java Programs

package com.instanceofjavaforus;
import java.util.ArrayList;
public class AddElementAtSpecifiedIndex {
public static void main(String[] args) {
//create an ArrayList object
ArrayList arrayList = new ArrayList();
//Add elements to Arraylist
arrayList.add("a");
arrayList.add("b");
arrayList.add("c");
arrayList.add("d");
arrayList.add("f");
arrayList.add("g");
arrayList.add(1,"Y");
System.out.println("ArrayList values...");
//display elements of ArrayList
for(int index=0; index < arrayList.size(); index++)
System.out.println(arrayList.get(index));
arrayList.add(2,"Z");
System.out.println("ArrayList values...");
//display elements of ArrayList
for(int index=0; index < arrayList.size(); index++)
System.out.println(arrayList.get(index));
}
}
}

OutPut:
ArrayList values...
a
Y
b
c
d
f
g
ArrayList values...
a
Y
Z
b
c
d
f
g

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