Nishant Sharma

How to find string whether it is palindrome or not in java ??

package org.cmania;

public class PalindromeString
{
public static void main(String[] args)
{
String inputString="aabaa"; //String to be reversed
System.out.println(isPalindrome(inputString) ? inputString+ " is a palindrome." : inputString+ "is not a palindrome.");
}

/*
* returns true if inputString is palindrome.
*/

public static boolean isPalindrome(String inputString)
{
char ar[]=inputString.toCharArray();
for(int i=0,j=ar.length-1; i<(ar.length/2); i++,j--){
if(ar[i]!=ar[j])
return false;
}
return true;

}

}

How to remove duplicate elements from sorted array in java ??

package org.cmania;

public class RemoveDuplicacyFromSortedArray
{
public static void main(String[] args)
{
int[] duplicateSortedAr = {1,3,7,8,8,9,14,16,16,17,17};
int[] nonDuplicateSortedAr = removeDuplicates(duplicateSortedAr);

System.out.print("Displaying contents of sorted array(with duplicate elements) : ");
for(int i=0;i<duplicateSortedAr.length;i++){
System.out.print(duplicateSortedAr[i]+" ");
}

System.out.println();
System.out.print("Displaying contents of sorted array(with non-duplicate elements) : ");
for(int i=0;i<nonDuplicateSortedAr.length;i++){
System.out.print(duplicateSortedAr[i]+" ");
}

}

/**
* This method returns sorted array with non duplicate elements
*/

public static int[] removeDuplicates(int[] duplicateSortedAr)
{

int i=0, j=1;

if(duplicateSortedAr.length < 2){ //means there is only one element in array.
return duplicateSortedAr;
}

while(j < duplicateSortedAr.length){
if(duplicateSortedAr[j] == duplicateSortedAr[i])
j++;
else
duplicateSortedAr[++i] = duplicateSortedAr[j++];
}

int[] nonDuplicateSortedAr = new int[i+1];
for(int x=0; x<nonDuplicateSortedAr.length; x++){
nonDuplicateSortedAr[x] = duplicateSortedAr[x];
}

return nonDuplicateSortedAr;
}

}

How to find a number is binary or not in java ??

package org.cmania;

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

int n=11001011;
System.out.println(isBinaryNumber(n)? n+" is binary number." : n+" is not binary number.");
n=11001110;
System.out.println(isBinaryNumber(n)? n+" is binary number." : n+" is not binary number.");
n=10000112;
System.out.println(isBinaryNumber(n)? n+" is binary number." : n+" is not binary number.");
n=11005110;
System.out.println(isBinaryNumber(n)? n+" is binary number." : n+" is not binary number.");
}

/**
* returns true if number is binary.
*/
public static boolean isBinaryNumber(int n){
while(n != 0){
if(n%10 > 1){
return false; //number containing any digit greater than 1 means its not binary.
}
n = n/10;
}
return true;
}

}

How to find Prime number in java ??

package org.cmania;

public class PrimeTime
{
public static void main(String[] args)
{
int n=11;
System.out.println(isPrimeNumber(n)? n+" is prime number." : n+" is not prime number."); n=12;
System.out.println(isPrimeNumber(n)? n+" is prime number." : n+" is not prime number."); n=13;
System.out.println(isPrimeNumber(n)? n+" is prime number." : n+" is not prime number."); n=14;
System.out.println(isPrimeNumber(n)? n+" is prime number." : n+" is not prime number.");
}

/** * returns true if number is prime using ternary operator. */

public static boolean isPrimeNumber(int n)
{
for(int i=2;i<=Math.sqrt(n);i++)
{
if(n%i==0)
{
return false;
}
}
return true; //means number wasn't divisible by any of the number, it's a prime number.
}
}

How to Reverse number in java ??

package org.cmania;

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

int number=12345; //number to be reversed

System.out.println("Original number: "+number); System.out.println("Reversed number: "+reverseNumber(number));

}

public static int reverseNumber(int number)

{ int reverse=0; int remainder; while(number>0){ remainder=number%10; number=number/10; reverse=reverse*10+remainder; } return reverse; }

}

Reverse String - keeping performance in mind (without StringBuffer) in java

package org.cmania;

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

String str="abcde"; //String to be reversed

System.out.println("Original String: "+str);
System.out.println("Reversed String: "+reverseString(str));
}

/*
* return reversed String with best performance.
* Best case: O(n/2)- (1/2), when we have odd number of characters in string.
* Average case: O(n/2) , generally when we have even number of characters in string.
* Worst case: O(n/2).
*/

public static String reverseString(String str)
{
char ar[]=str.toCharArray();
char temp;
for(int i=0,j=ar.length-1; i<(ar.length/2); i++,j--){
temp=ar[i];
ar[i]=ar[j];
ar[j]=temp;
}
return new String(ar);
}
}

How to check string contains numeric or alphabet in java string by using Regex(Regular Expression) ??

package org.cmania;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class StringNumericRegex {

public static void main(String[] args)
{
Pattern pat = Pattern.compile(".*\\d.*"); // for digit detection only

// Pattern pat = Pattern.compile("[a-zA-Z]+"); for alphabetic detection

// Pattern pat = Pattern.compile("[a-zA-Z ]*\\d+.*"); for digit detection

// org.apache.commons.lang.StringUtils.isAlpha(str); for alphabetic detection

String str = "java8";

/**
* Except for splitting a string, you need to create a Matcher object from the Pattern object.
* The Matcher will do the actual work. The adv of having two separate classes is that
* you can create many Matcher objects from a single Pattern object, and thus apply the
* regular expression to many subject strings simultaneously.
*/

Matcher match = pat.matcher(str);

if (match.matches())
{
System.out.println("String contains numeric values");
}
else
{
System.out.println("String doesn't contain any numberic values");
}

}

}