Question

How to convert a character inside string to lowercase in Java

Answer 1

public class MyClass {
    public static String char_to_lowercase(String s, int idx) { 
        if (idx > 0) idx--;
        if (idx < 0 || idx > s.length()) return s;
        
        String tmp = "";
        for (int i = 0; i < s.length(); i++) {
            if (i == idx) {
                char ch = s.charAt(i);
                tmp += Character.toLowerCase(ch);
            }
            else
                tmp += s.charAt(i); 
        }
            
        return tmp;
    }
    public static void main(String args[]) {
        String s = "JAVA PROGRAMMING"; 

        s = char_to_lowercase(s, 4);
        System.out.println(s); 
        
        s = char_to_lowercase(s, 0);
        System.out.println(s); 
        
        s = char_to_lowercase(s, s.length());
        System.out.println(s); 
    }
}
  


/*
run:
  
JAVa PROGRAMMING
jAVa PROGRAMMING
jAVa PROGRAMMINg
  
*/

 

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Answer 2

public class MyClass {
    public static String char_to_lowercase(String s, int idx) { 
        if (idx < 0 || idx > s.length()) return s;
         
        String tmp = "";
        for (int i = 0; i < s.length(); i++) {
            if (i == idx) {
                char ch = s.charAt(i);
                tmp += Character.toLowerCase(ch);
            }
            else
                tmp += s.charAt(i); 
        }
             
        return tmp;
    }
    public static void main(String args[]) {
        String s = "JAVA PROGRAMMING"; 
 
        s = char_to_lowercase(s, 3);
        System.out.println(s); 
         
        s = char_to_lowercase(s, 0);
        System.out.println(s); 
         
        s = char_to_lowercase(s, s.length() - 1);
        System.out.println(s); 
    }
}
   
 
 
/*
run:
   
JAVa PROGRAMMING
jAVa PROGRAMMING
jAVa PROGRAMMINg
   
*/

 

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Answer 3

public class MyClass {
    public static String char_to_lowercase(String s, int idx) { 
        if (idx < 0 || idx > s.length()) return s;
          
        if (idx == s.length()) {
            s = s.substring(0, idx - 1) + s.substring(idx - 1, idx).toLowerCase();
        } else if (idx > 0) {
                   s = s.substring(0, idx - 1) + s.substring(idx - 1, idx).toLowerCase() + s.substring(idx);
               }
               else {
                  s = s.substring(0, idx + 1).toLowerCase() + s.substring(idx + 1);
               }
              
        return s;
    }
    public static void main(String args[]) {
        String s = "JAVA PROGRAMING"; 
  
        s = char_to_lowercase(s, 4);
        System.out.println(s); 
          
        s = char_to_lowercase(s, 0);
        System.out.println(s); 
          
        s = char_to_lowercase(s, s.length());
        System.out.println(s); 
    }
}
  
    
    
/*
run:
    
JAVa PROGRAMING
jAVa PROGRAMING
jAVa PROGRAMINg
    
*/

 

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Answer 4

public class MyClass {
    public static String char_to_lowercase(String s, int idx) { 
        if (idx > 0) idx++;
        if (idx < 0 || idx > s.length()) return s;
          
        if (idx == s.length()) {
            s = s.substring(0, idx - 1) + s.substring(idx - 1, idx).toLowerCase();
        } else if (idx > 0) {
                   s = s.substring(0, idx - 1) + s.substring(idx - 1, idx).toLowerCase() + s.substring(idx);
               }
               else {
                  s = s.substring(0, idx + 1).toLowerCase() + s.substring(idx + 1);
               }
              
        return s;
    }
    public static void main(String args[]) {
        String s = "JAVA PROGRAMING"; 
  
        s = char_to_lowercase(s, 3);
        System.out.println(s); 
          
        s = char_to_lowercase(s, 0);
        System.out.println(s); 
          
        s = char_to_lowercase(s, s.length() - 1);
        System.out.println(s); 
    }
}
  
    
    
/*
run:
    
JAVa PROGRAMING
jAVa PROGRAMING
jAVa PROGRAMINg
    
*/

 

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