Need help in these topics. Or links please

Question

Hi guys,
Could you tell me a resource where I can find information on these.
1. Programs written in java to manipulate on String functionaliy like String concat, substring, length and other string methods without using String's Builtin functions.
2. Java resource for Searching and Sorting Algorithms

Answer 1

I shall take a look at Source code that comes with JDK....
I have implemented something for String Concatenation ... I hope its correct....
public class StringConcatEx {
   public StringConcatEx() { }
   public char[] concat(char[] x, char[] y) {
       boolean done;
       char [] ret;
       int len = 0;
       len += x.length;
       len += y.length;
       ret = new char[len];
       for(int i= 0; i<x.length; i++ ){
            ret[i] = x;
for(int i= 0; i<y.length; i++ ){
     ret[x.length + i] = y[i];
return ret;
public static void main(String [] args) {
char charArray[];
StringConcatEx te = new StringConcatEx();
charArray = te.concat("foo".toCharArray(), "bar".toCharArray());
System.out.println("The Concatenated String is = '" + (new String(charArray)) + "'");