Java Program to find String is Palindrome or not

In this post you will learn to find String is Palindrome or not. Frequently asking in technical interview about programming logic.
Definition 1 : If Reverse of String is same as Original One then it is called as String Palindrome.
Definition 2: If String Reads the same backward and forward then it is called String palindrome.

Example: Original String="MADAM"

                   Palindrome String="MADAM" //string is palindrome

                   Original String="lucky"

                   Palindrome String="ykcul"// This is NOT String palindrome


Program 1: This Program is developed using String API.

import java.io.*;

class Palindrome
{
public static void main(String args[]) throws IOException
{
String str;
System.out.println("Enter a string");
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
str=br.readLine();
StringBuffer sb=new StringBuffer(str);
String revstr=new String(sb.reverse());
if(revstr.equalsIgnoreCase(str))
System.out.println("String is palindrome");
else
System.out.println("Not a Palindrome String!");
}
}

Output:
Enter a String : MADAM
String is Palindrome;


Program 2: Java Program to find Whether the String is Palindrome or not Using Recursion method.

import java.util.*;

class StringPalindrome{
public static void main(String args[])
{
Scanner sc=new Scanner(System.in);
System.out.println("Enter a String:");
String st=sc.next();
StringPalindrome sp=new StringPalindrome();
String reverseString=sp.reverse(st);
if(st.equalsIgnoreCase(reverseString))
{
System.out.printf("The string is palindrome",st);
}
else
{
System.out.printf("the String is not Palindrome",st);
}
}
//method to return the reverse of string
public String reverse(String str)
{
StringBuilder revStr=new StringBuilder();
for(int i=str.length()-1;i>=0;i--)
{
revStr.append(str.charAt(i));
}
return revStr.toString();
}
}

Output:
Enter a String:   lucky
The String is not Palindrome

Java Program to Multiply 2 matrices

In this program we will take three level nested loop is used to perform the multiplication.First, you have to ask the user to enter the number of rows and columns of the first matrix and then ask to enter the first matrix elements.Again ask the same for the second matrix. Then multiply two matrices and store the multiplication result inside the any variable say res and then print all the matrices as a result


Example:


import java.util.Scanner;
class MatrixExample
{
int m,n,p,q;
int[][] a;
int[][]b;
int[][]c;
public void readData()
{
int i,j;
Scanner sc=new Scanner(System.in);
System.out.println("Enter the order of the matrix A");
m=sc.nextInt();
n=sc.nextInt();
System.out.println("Enter the order of the matrix B");
p=sc.nextInt();
q=sc.nextInt();
if(n!=p)
{
System.out.println("matrix order mismatch for multiplication");
System.exit(0);
}
a=new int[m][n];
b=new int[p][q];
c=new int[m][q];
System.out.println("enter the elements of Matrix A");
for(i=0;i<m;i++)
for(j=0;j<n;j++)
{
System.out.printf("a[%d][%d]=",i,j);
a[i][j]=sc.nextInt();
System.out.println("\n");
}
System.out.println("enter the elements of Matrix B");
for(i=0;i<p;i++)
for(j=0;j<q;j++)
{
System.out.printf("b[%d][%d]=",i,j);
b[i][j]=sc.nextInt();
System.out.println("\n");
}
}
public void multiply()
{
for(int i=0;i<m;i++)
for(int j=0;j<q;j++)
{
c[i][j]=0;
for(int k=0;k<n;k++)
c[i][j]+=a[i][k]*b[k][j];
}
}
public void printMatrix()
{
for(int i=0;i<m;i++)
{
for(int j=0;j<q;j++)
System.out.printf("%d\t",c[i][j]);
System.out.println("\n");
}
}
public static void main(String []args)
{
MatrixExample obj=new MatrixExample();
obj.readData();
obj.multiply();
System.out.println("The result of multiplication is ");
obj.printMatrix();
}
}
Output:

Java Program to Print Prime Numbers

A Prime Number is a natural number  or positive integer  greater than 1 that has no positive divisors other than 1 and itself.

Examples: 2,3,5,7,11,13,15,17...

Program:


class primeNumber
{
public static void main(String args[]){
int i,s,j;
for(i=2;i<100;i++)
{
s=0;
for(j=2;j<i;j++)
{
if(i%j==0)
{
s=1;
break;
}
}
if(s==0)
{
System.out.println(i);
}
}
}
}                         

Output:

Explanation:

The logic behind to the above program is all about to divide the number which you want to check whether it is prime or not by the number less than itself continuously and if the reminder of any of these division is zero then that entered number is not a prime.

How to upload Image by using JSP

In this post you will learn how to upload image using JSP and display it on the browser.

first we will create page.jsp

page.jsp:

<%@ page language="java" %>
<HTML>
<HEAD><TITLE>Display file upload form to the user</TITLE></HEAD>
<BODY> <FORM ENCTYPE="multipart/form-data" ACTION="upload.jsp" METHOD=POST>
<br><br><br>
<table border="0" bgcolor=#ccFDDEE>
<tr>
<td colspan="2" align="center"><B>UPLOAD THE FILE</B><center></td>
</tr>
<tr>
<td colspan="2" align="center"> </td>
</tr>
<tr>
<td><b>Choose the file To Upload:</b></td>
<td><INPUT NAME="file" TYPE="file"></td>
</tr>
<tr>
<td colspan="2" align="center"> </td>
</tr>
<tr>
<td colspan="2" align="center"><input type="submit" value="Send File"> </td>
</tr>
<table>
</FORM>
</BODY>
</HTML>

Now we will develop upload file using jsp:

upload.jsp:

<%@ page import="java.io.*" %>
<%@ page import="java.sql.*" %>
<%!
private byte[] getImage(String filename) {
byte[] result = null;
String fileLocation = filename;
File f = new File(fileLocation);
result = new byte[(int)f.length()];
try {
FileInputStream in = new FileInputStream(fileLocation);
in.read(result);
}
catch(Exception ex) {
System.out.println("GET IMAGE PROBLEM :: "+ex);
ex.printStackTrace();
}
return result;
}
%>
<%
String saveFile="";
String contentType = request.getContentType();
if((contentType != null)&&(contentType.indexOf("multipart/form-data") >= 0)){
DataInputStream in = new DataInputStream(request.getInputStream());
int formDataLength = request.getContentLength();
byte dataBytes[] = new byte[formDataLength];
int byteRead = 0;
int totalBytesRead = 0;
while(totalBytesRead < formDataLength){
byteRead = in.read(dataBytes, totalBytesRead,formDataLength);
totalBytesRead += byteRead;
}
String file = new String(dataBytes);
saveFile = file.substring(file.indexOf("filename=\"") + 10);
saveFile = saveFile.substring(0, saveFile.indexOf("\n"));
saveFile = saveFile.substring(saveFile.lastIndexOf("\\") + 1,saveFile.indexOf("\""));
int lastIndex = contentType.lastIndexOf("=");
String boundary = contentType.substring(lastIndex + 1,contentType.length());
int pos;
pos = file.indexOf("filename=\"");
pos = file.indexOf("\n", pos) + 1;
pos = file.indexOf("\n", pos) + 1;
pos = file.indexOf("\n", pos) + 1;
int boundaryLocation = file.indexOf(boundary, pos) - 4;
int startPos = ((file.substring(0, pos)).getBytes()).length;
int endPos = ((file.substring(0, boundaryLocation)).getBytes()).length;
File ff = new File(saveFile);
FileOutputStream fileOut = new FileOutputStream(ff);
fileOut.write(dataBytes, startPos, (endPos - startPos));
fileOut.flush();
fileOut.close();

response.reset();
response.setHeader("Content-Disposition", "inline");
response.setHeader("Cache-Control", "no-cache");
response.setHeader("Expires", "0");
response.setContentType("image/jpg");
byte[] image = getImage(saveFile);
OutputStream outputStream = response.getOutputStream();
outputStream.write(image);
outputStream.close();
}
%>

How to create a table by using loop in java

In this post you will learn how to print a table using while loop. As we know looping statements are used to repeat a statement until the specified the condition becomes false.

Now we will see the the example of this program;

class  Table{
public static void main(String[] args) {
int a=10, b=1;
System.out.println("the table of "+a+"= ");
while(b<=10){
int c = a*b;
System.out.println(c);
b = b+1;
}
}
}

Output:
javac Table.java
java Table
the table of 10=
10*1=10
10*2=20
10*3=30
10*4=40
10*5=50
10*6=60
10*7=70
10*8=80
10*9=90
10*10=100