string builders

public class StringBuilders {
    public static void main(String[] args) {
        String str="ABCDEFGH";
        System.out.println("string length="+str.length());
        System.out.println("string replace:"+str.replace("ABCDEFGH","abcdefgh"));
        System.out.println("Index:"+str.indexOf("D"));
        System.out.println("string charat: "+str.charAt(5));
        System.out.println("string uppercase: "+str.toUpperCase());
        System.out.println("string lowercase: "+str.toLowerCase());
        System.out.println("string tostring"+str.toString());
        System.out.println("string concat"+str.concat("I"));
        //System.out.println("capitalize: "+str.capitalize());


    }
}