Question

How to convert part of a string between two indexes to lowercase in Java

Answer 1

public class MyClass {
    public static String convert_part_to_lowercase(String s, int from_idx, int to_idx) { 
        if (from_idx < 0 || to_idx > s.length()) return s;
            
        String tmp = "";
        for (int i = 0; i < s.length(); i++) {
            if ((i >= from_idx && i <= to_idx) && (s.charAt(i) >= 65 && s.charAt(i) <= 90)) {
                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 = convert_part_to_lowercase(s, 3, 6);
        System.out.println(s);
          
        s = convert_part_to_lowercase(s, 11, 12);
        System.out.println(s);
    }
}
  
  
  
  
/*
run:
  
JAVa prOGRAMMING
JAVa prOGRAmmING
 
*/

 

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Answer 2

public class ConvertPartOfAStringToLowercase_Java {
    public static String convert_part_to_lowercase(String s, int startIndex, int endIndex) { 
        String partToLower = s.substring(startIndex, endIndex).toLowerCase();

        return s.substring(0, startIndex) + partToLower + s.substring(endIndex);
    }
    public static void main(String args[]) {
        String s = "JAVA PROGRAMMING";
   
        s = convert_part_to_lowercase(s, 3, 6);
        System.out.println(s);
           
        s = convert_part_to_lowercase(s, 11, 12);
        System.out.println(s);
    }
}


/*
run:

JAVa pROGRAMMING
JAVa pROGRAmMING

*/

 

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