JAVA EXAMPLE PROGRAMS

JAVA EXAMPLE PROGRAMS

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Program: Write a program to find out duplicate characters in a string.


Description:
Write a program to find out duplicate or repeated characters in a
string, and calculate the count of repeatation.

Code:
package com.java2novice.algos;

import java.util.HashMap;
import java.util.Map;
import java.util.Set;

public class DuplicateCharsInString {

	public void findDuplicateChars(String str){
		
		Map<Character, Integer> dupMap = new HashMap<Character, Integer>(); 
		char[] chrs = str.toCharArray();
		for(Character ch:chrs){
			if(dupMap.containsKey(ch)){
				dupMap.put(ch, dupMap.get(ch)+1);
			} else {
				dupMap.put(ch, 1);
			}
		}
		Set<Character> keys = dupMap.keySet();
		for(Character ch:keys){
			if(dupMap.get(ch) > 1){
				System.out.println(ch+"--->"+dupMap.get(ch));
			}
		}
	}
	
	public static void main(String a[]){
		DuplicateCharsInString dcs = new DuplicateCharsInString();
		dcs.findDuplicateChars("Java2Novice");
	}
}

Output:
v--->2
a--->2
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  14. Write a program to find common elements between two arrays.
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  18. Write a program to check the given number is a prime number or not?
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  20. Write a program to convert binary to decimal number.
  21. Write a program to check the given number is binary number or not?
  22. Write a program for Bubble Sort in java.
  23. Write a program for Insertion Sort in java.
  24. Write a program to implement hashcode and equals.
  25. How to get distinct elements from an array by avoiding duplicate elements?
  26. Write a program to get distinct word list from the given file.
  27. Write a program to get a line with max word count from the given file.
  28. Write a program to convert string to number without using Integer.parseInt() method.
  29. Write a program to find two lines with max characters in descending order.
  30. Write a program to find the sum of the first 1000 prime numbers.
  31. Find longest substring without repeating characters.
  32. Write a program to remove duplicates from sorted array.
Knowledge Centre
What is System.out in Java
In System.out, out is an instance of PrintStream. It is a static member variable in System class. This is called standard output stream, connected to console.

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