replace string java online

1public static void main(String args[]){  
2String s1="my name is khan my name is java";  
3String replaceString=s1.replace("is","was");//replaces all occurrences of "is" to "was"  
4System.out.println(replaceString);  
5}}  
6

1String str = ".............................."; 
2
3        int index = 5; 
4  
5        char ch = '|'; 
6 
7        StringBuilder string = new StringBuilder(str); 
8        string.setCharAt(index, ch); 
9
10        System.out.println(string); 

1rtgret