import java.util.HashSet;
import javax.swing.JOptionPane;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
/*
 * Permutations.java
 *
 * Created on November 3, 2005, 5:40 PM
 *
 */

/**
 *
 * @author Bill Kraynek
 */
public class Permutations {
    
    static HashSet<String> getPermutations(String word) {
        if( word.length() == 1 ) {
            HashSet<String> p = new HashSet<String>();
            p.add(word);
            //JOptionPane.showMessageDialog(null,p);
            return p;
        } // end if
        HashSet<String> p = getPermutations(word.substring(0, word.length()-1));
        //JOptionPane.showMessageDialog(null,p);
        HashSet<String> permutations = new HashSet<String>();
        char lastLetter = word.charAt(word.length()-1);
        for( String next : p ) {
            StringBuilder rest = new StringBuilder(next);
            for( int j = 0; j < word.length(); j++ ) {
                rest.insert(j,lastLetter);
                permutations.add(rest+"");
                rest.deleteCharAt(j);
            } // end for
        } // end for
        return permutations;
    } // end getPermutations
    
    public static void main(String[] args) {
        // Test the permutations method
        while(true) {
            String aWord = JOptionPane.showInputDialog("Enter a word. The number of letters must be less than 9");
            if( aWord == null) return;
            if( aWord.length() >= 9 ) continue;
            HashSet<String> permutations = Permutations.getPermutations(aWord);
            StringBuilder out = new StringBuilder("Permutations for " + aWord + "\n\n");
            for( String next : permutations ) out.append(next + "\n");
            JTextArea outArea = new JTextArea(out+"",20,30);
            JOptionPane.showMessageDialog(null, new JScrollPane(outArea));
        } // end while
    }
    
}