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appending arguments to a String

I need to write a simple Java program so as to step through a given string (given from args[]), and receive a println once a certain character (e.g. ‘^’) is encountered. However, I cannot find why I cannot receive such println. Could you please check what is the stem of the error?

public class JavaApplication15 {

    public static void main(String[] args) {
        StringBuffer copyFromMe = null;
        for (int j = args.length; --j<=0; ) {
            copyFromMe = new StringBuffer();

        StringBuffer copyToMe = new StringBuffer();

        int i = 0;
        char c = copyFromMe.charAt(i);
        while (c != 'g') {
            c = copyFromMe.charAt(++i);

    private static String String(String[] args) {
        throw new UnsupportedOperationException("Not supported yet.");


You’re creating a new StringBuffer with every iteration of your loop. You should use a StringBuilder. And you need to start at args.length - 1. Finally >= 0 like ,

StringBuilder copyFromMe = new StringBuilder();
for (int j = args.length - 1; j>=0; j--) {
  // copyFromMe = new StringBuffer();