问没有所需的输出，可能的原因是过载

EN

if (fu == "bar") {
  // do something
}

if (fu.equals("bar")) {
  // do something
}

if (fu.equalsIgnoreCase("bar")) {
  // do something
}

import java.util.Comparator;

public enum HandGameChoice  {
   ROCK,
   PAPER,
   SCISSORS,
   LIZARD,
   SPOCK;

   private static MyComparator myComparator = new MyComparator();

   public static int compare(HandGameChoice o1, HandGameChoice o2) {
      return myComparator.compare(o1, o2);
   }

   private static class MyComparator implements Comparator<HandGameChoice> {
      private int[][] winMatrix = {
            { 0, -1,  1,  1, -1},
            { 1,  0, -1, -1,  1},
            {-1,  1,  0,  1, -1},
            {-1,  1, -1,  0,  1},
            { 1, -1,  1, -1,  0}
      };

      @Override
      public int compare(HandGameChoice o1, HandGameChoice o2) {
         return winMatrix[o1.ordinal()][o2.ordinal()];
      }
   }
}

public class TestHandGameChoices {
   public static void main(String[] args) {
      for (HandGameChoice choice1 : HandGameChoice.values()) {
         for (HandGameChoice choice2 : HandGameChoice.values()) {
            int value = HandGameChoice.compare(choice1, choice2);
            String result = "";
            if (value > 0) {
               result = "win";
            } else if (value < 0) {
               result = "lose";
            } else {
               result = "tie";
            }
            System.out.printf("%-8s vs %-8s: %s%n", choice1, choice2, result);
         }
      }
   }
}

ROCK     vs ROCK    : tie
ROCK     vs PAPER   : lose
ROCK     vs SCISSORS: win
ROCK     vs LIZARD  : win
ROCK     vs SPOCK   : lose
PAPER    vs ROCK    : win
PAPER    vs PAPER   : tie
PAPER    vs SCISSORS: lose
PAPER    vs LIZARD  : lose
PAPER    vs SPOCK   : win
SCISSORS vs ROCK    : lose
SCISSORS vs PAPER   : win
SCISSORS vs SCISSORS: tie
SCISSORS vs LIZARD  : win
SCISSORS vs SPOCK   : lose
LIZARD   vs ROCK    : lose
LIZARD   vs PAPER   : win
LIZARD   vs SCISSORS: lose
LIZARD   vs LIZARD  : tie
LIZARD   vs SPOCK   : win
SPOCK    vs ROCK    : win
SPOCK    vs PAPER   : lose
SPOCK    vs SCISSORS: win
SPOCK    vs LIZARD  : lose
SPOCK    vs SPOCK   : tie

import java.awt.*;
import java.awt.event.*;
import java.util.Random;
import javax.swing.*;

@SuppressWarnings("serial")
public class HandGameGui extends JPanel {
   private JTextArea tArea = new JTextArea(13, 40);

   public HandGameGui() {
      ButtonListener btnListener = new ButtonListener();
      JPanel btnPanel = new JPanel(new GridLayout(1, 0, 5, 0));
      for (HandGameChoice hgChoice : HandGameChoice.values()) {
         String choiceString = hgChoice.name();
         String initCapChoiceString = choiceString.substring(0, 1)
               + choiceString.substring(1, choiceString.length()).toLowerCase();

         JButton button = new JButton(initCapChoiceString);
         button.setActionCommand(choiceString);
         button.addActionListener(btnListener);
         btnPanel.add(button);
      }

      setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
      setLayout(new BorderLayout(5, 5));
      add(new JScrollPane(tArea, JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
            JScrollPane.HORIZONTAL_SCROLLBAR_NEVER), BorderLayout.CENTER);
      add(btnPanel, BorderLayout.PAGE_END);
   }

   private class ButtonListener implements ActionListener {
      private Random random = new Random();
      @Override
      public void actionPerformed(ActionEvent e) {
         String actionCommand = e.getActionCommand();
         HandGameChoice userChoice = HandGameChoice.valueOf(actionCommand);
         int randomInt = random.nextInt(HandGameChoice.values().length);
         HandGameChoice aiChoice = HandGameChoice.values()[randomInt];

         int gameResult = HandGameChoice.compare(userChoice, aiChoice);
         String resultStr = "";
         if (gameResult > 0) {
            resultStr = "win";
         } else if (gameResult < 0) {
            resultStr = "lose";
         } else {
            resultStr = "tie";
         }

         String output = String.format("You chose %s, and the computer chose %s; you %s%n", 
               userChoice, aiChoice, resultStr);
         tArea.append(output);
      }
   }

   private static void createAndShowGui() {
      HandGameGui mainPanel = new HandGameGui();

      JFrame frame = new JFrame("Rock Paper Scissors Lizard Spock");
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.getContentPane().add(mainPanel);
      frame.pack();
      frame.setLocationByPlatform(true);
      frame.setVisible(true);
   }

   public static void main(String[] args) {
      SwingUtilities.invokeLater(new Runnable() {
         public void run() {
            createAndShowGui();
         }
      });
   }
}