replace a char with a string in java code example

Example 1: replace character in string java

String str = ".............................."; 

        int index = 5; 
  
        char ch = '|'; 
 
        StringBuilder string = new StringBuilder(str); 
        string.setCharAt(index, ch); 

        System.out.println(string);

Example 2: java replaceall single character

.replaceAll("(?<!\\S)[^ ](?!\\S)", " ").trim()