[英]Why isn't this program repainting a certain part of an applet even when repaint() is called
这是一个简单的石头,纸,剪刀的小食。 有3个变量记录获胜,失败和平局。 然后是一个用于显示它们的标签。 当我使用调试器时,将调用repaint方法,所以我不明白为什么小程序的这一部分没有更新。
import java.awt.Font;
import java.awt.Graphics;
import javax.swing.JApplet;
import javax.swing.JLabel;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.util.Random;
public class JRockPaperScissors extends JApplet {
JLabel lblDescision = new JLabel("descision");
JLabel lblWinner = new JLabel("winner");
JLabel lblTally = new JLabel("tally");
int tally_user = 0;
int tally_comp = 0;
int tally_ties = 0;
/**
* Create the applet.
*/
public JRockPaperScissors() {
setSize(500,500);
getContentPane().setLayout(null);
JLabel lblRockPaperScissors = new JLabel("Rock, Paper, Scissors");
lblRockPaperScissors.setBounds(95, 50, 280, 48);
getContentPane().add(lblRockPaperScissors);
Font arial_1 = new Font("Arial", Font.BOLD, 25);
lblRockPaperScissors.setFont(arial_1);
JLabel lblChooseOneButton = new JLabel("Choose one button");
lblChooseOneButton.setBounds(10, 93, 146, 25);
getContentPane().add(lblChooseOneButton);
Font arial_2 = new Font("Arial", Font.BOLD, 15);
lblChooseOneButton.setFont(arial_2);
JButton btnRock = new JButton("Rock");
btnRock.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
determine_winner(0);
repaint();
}
});
btnRock.setBounds(166, 95, 89, 23);
getContentPane().add(btnRock);
JButton btnPaper = new JButton("Paper");
btnPaper.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
determine_winner(1);
}
});
btnPaper.setBounds(265, 95, 89, 23);
getContentPane().add(btnPaper);
JButton btnScissors = new JButton("Scissors");
btnScissors.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
determine_winner(2);
}
});
btnScissors.setBounds(361, 95, 89, 23);
getContentPane().add(btnScissors);
JLabel lblresults = new JLabel("------Results------");
lblresults.setBounds(20, 114, 126, 25);
getContentPane().add(lblresults);
Font arial_3 = new Font("Arial", Font.BOLD, 15);
lblresults.setFont(arial_3);
lblDescision.setBounds(30, 150, 311, 14);
getContentPane().add(lblDescision);
lblWinner.setBounds(20, 175, 146, 14);
getContentPane().add(lblWinner);
JLabel lblTally = new JLabel("You:" + tally_user + " Computer:" + tally_comp +
" Ties:"+ tally_ties);
lblTally.setBounds(20, 214, 201, 30);
getContentPane().add(lblTally);
}
public void determine_winner(int user_choice){
Random random = new Random();
int computer_choice = random.nextInt(3);
if(user_choice == 0 ){
if(computer_choice ==0){
lblDescision.setText("You picked Rock --- Computer picked Rock");
lblWinner.setText("Winner: Tie");
tally_ties +=1;
}
else if(computer_choice ==1){
lblDescision.setText("You picked Rock --- Computer picked Paper");
lblWinner.setText("Winner: Computer");
tally_comp +=1;
}
else if(computer_choice ==2){
lblDescision.setText("You picked Rock --- Computer picked Scissors");
lblWinner.setText("Winner: You");
tally_user +=1;
}
}
else if(user_choice == 1){
if(computer_choice ==0){
lblDescision.setText("You picked Paper --- Computer picked Rock");
lblWinner.setText("Winner: You");
tally_user +=1;
}
else if(computer_choice ==1){
lblDescision.setText("You picked Paper --- Computer picked Paper");
lblWinner.setText("Winner: Tie");
tally_ties +=1;
}
else if(computer_choice ==2){
lblDescision.setText("You picked Paper --- Computer picked Scissors");
lblWinner.setText("Winner: Computer");
tally_comp +=1;
}
}
else if(user_choice == 2){
if(computer_choice ==0){
lblDescision.setText("You picked Scissors --- Computer picked Rock");
lblWinner.setText("Winner: Computer");
tally_comp +=1;
}
else if(computer_choice ==1){
lblDescision.setText("You picked Scissors --- Computer picked Paper");
lblWinner.setText("Winner: You");
tally_user +=1;
}
else if(computer_choice ==2){
lblDescision.setText("You picked Scissors --- Computer picked Scissors");
lblWinner.setText("Winner: Tie");
tally_ties +=1;
}
}
revalidate();
repaint();
}
}
lblTally.setText(someNewString);
其他附带问题(与您的问题不直接相关的问题)是:
null
布局。 您将要避免使用空布局和使用setBounds(...)
进行组件放置,因为这会导致非常不灵活的GUI,尽管它们在一个平台上看起来不错,但在大多数其他平台或屏幕分辨率上却看起来很糟糕,而且非常难以更新和维护。 init()
方法,该方法应该启动并运行applet。 revalidate()
或repaint()
。 简而言之,您正在做的是这样的:
import java.awt.event.ActionEvent;
import javax.swing.*;
public class JRockPaperEtc extends JApplet {
private static final String FORMAT_TXT = "Tally: %03d";
private int tally = 0;
private JLabel lblTally = new JLabel(String.format(FORMAT_TXT, tally));
@Override
public void init() {
JPanel mainPanel = new JPanel();
// *** Variable Shadowing here
JLabel lblTally = new JLabel("Tally: 000");
mainPanel.add(lblTally);
JButton button = new JButton(new AbstractAction("Push") {
@Override
public void actionPerformed(ActionEvent e) {
tally++;
// *** lblTally's text is never changed
}
});
mainPanel.add(button);
add(mainPanel);
}
}
当您应该这样做时:
import java.awt.event.ActionEvent;
import javax.swing.*;
public class JRockPaperEtc2 extends JApplet {
private static final String FORMAT_TXT = "Tally: %03d";
private int tally = 0;
private JLabel lblTally = new JLabel(String.format(FORMAT_TXT, tally));
@Override
public void init() {
JPanel mainPanel = new JPanel();
// lblTally = new JLabel("Tally: 000"); // *** no shadowing
mainPanel.add(lblTally);
JButton button = new JButton(new AbstractAction("Push") {
@Override
public void actionPerformed(ActionEvent e) {
tally++;
lblTally.setText(String.format(FORMAT_TXT, tally));
// *** lblTally's text is now changed
}
});
mainPanel.add(button);
add(mainPanel);
}
}
另外,您问:
那么您会怎么做而不是设定界限? 我刚刚开始学习gui应用程序,所以请问这是一个非常深入的问题。
代替setBounds()
,使用布局管理器为您处理所有繁重的布局。 Google Swing布局管理器教程,看看吧。
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