Permutations

import java.util.*;
public class PermStr {

  public static void main(String[] args) {
    
    String inp = "0ab";
    if (args.length>0) inp = args[0];
    for (String str : permStr(inp)){
      System.out.println(str);
    }
  }
  
  static Vector<String> permStr(String str){
    
    if (str.length() == 1){
      Vector<String> ret = new Vector<String>();
      ret.add(str);
      System.out.println("   >ret:"+ret);
      return ret;
    }
    char start = str.charAt(0);
    Vector<String> endStrs = permStr(str.substring(1));
    Vector<String> newEndStrs = new Vector<String>();
    for (String endStr : endStrs){
      System.out.println("   >next:"+endStr);
      for (int j = 0; j <= endStr.length(); j++){
        System.out.println("   >j:"+j);
        if (endStr.substring(0, j).endsWith(String.valueOf(start)))
          break;
        System.out.println("   >endStr.substring(0, j)"+endStr.substring(0, j));
        System.out.println("   >String.valueOf(start)"+String.valueOf(start));
        System.out.println("   >endStr.substring(j);:"+endStr.substring(j));
        newEndStrs.add(endStr.substring(0, j) + String.valueOf(start) + endStr.substring(j));
      }
    }
    System.out.println("    >>return newEndStrs: "+newEndStrs);
    return newEndStrs;
  }
  
}

0ab
a0b
ab0
0ba
b0a
ba0