Question

How to replace a character at a specific index in a string with Java

Answer 1

public class Program {
    public static String replaceCharacter(String str, int index, char ch) { 
        if (index < 0 || index > str.length()) {
            return str;
        }
          
        String tmp = "";
        int size = str.length();
        for (int i = 0; i < size; i++) {
            if (i == index) {
                tmp += ch;
            }
            else {
                tmp += str.charAt(i); 
            }
        }
              
        return tmp;
    }
    public static void main(String args[]) {
        String str = "java c c++";
         
        str = replaceCharacter(str, 1, 'Z');
 
        System.out.println(str);
    }
}
 
 
 
 
/*
run:
 
jZva c c++
 
*/

 

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Answer 2

public class Program {
    public static String replaceCharacter(String str, int index, char ch) { 
        StringBuilder sb = new StringBuilder(str);
         
        sb.setCharAt(1, 'Z');
         
        return sb.toString();
    }
    
    public static void main(String args[]) {
        String str = "java c c++";
 
        str = replaceCharacter(str, 1, 'Z');
 
        System.out.println(str);
    }
}
 
 
 
 
/*
run:
 
jZva c c++
 
*/

 

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Answer 3

public class Program {
    public static String replaceCharacter(String str, int index, char ch) { 
        return str.substring(0, index) + ch + str.substring(index + 1);
    }
    
    public static void main(String args[]) {
        String str = "java 17";
 
        str = replaceCharacter(str, 1, 'Z');
 
        System.out.println(str);
    }
}


  
/*
run:
  
jZva 17
  
*/

 

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Answer 4

public class Program {
    static String replaceCharacter(String str, int index, char ch) {
		return (index > 0 ? str.substring(0, index) : "")
			+ Character.toString(ch) + (index < str.length() - 1 ? str.substring(index + 1) : "");
	}
	
    public static void main(String[] args) {
        String str = "java game programming";
        
        str = replaceCharacter(str, 6, '_');
        System.out.println(str);
        
        str = replaceCharacter(str, 0, 'J');
        System.out.println(str);
        
        str = replaceCharacter(str, str.length() - 1, '@');
        System.out.println(str);
    }
}



/*
run:
  
java g_me programming
Java g_me programming
Java g_me programmin@
  
*/

 

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