Question

我正在介绍Java，所以我只知道Java的基础知识。我已经找到了答案，但每当我找到有同样问题的人时，他们就会找到我不理解的代码。如果有人可以用尽可能简单的术语向我解释，那将非常感激。每当我进入我的do while循环（在我的代码底部）时，我的问题是我的Jframe冻结。通过研究我发现我应该放一个SwingWorker，但我不知道如何或在哪里。继承我的代码

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JTextField;

public class ATMSwingPanel extends JPanel
{
public  int count, Balance;
public String total, Input = "";
public JButton withdraw1,withdraw2,withdraw3,deposit,quit,num0,
num1,num2,num3,num4,num5,num6,num7,num8,num9,clear,enter;
public JLabel label, pinLabel, TextLabel;
public JTextField InputDisplay;

public ATMSwingPanel()

enter code here

{


    setLayout(new GridLayout(5, 6));;

    TextLabel = new JLabel("Please enter your pin");
    add(TextLabel);

    InputDisplay = new JTextField();
    InputDisplay.addActionListener(new ButtonListener());


    withdraw1 = new JButton("Withdraw $20");
    withdraw1.addActionListener(new ButtonListener());

    withdraw2 = new JButton("Withdraw $50");
    withdraw2.addActionListener(new ButtonListener());

    withdraw3 = new JButton("Withdraw $100");
    withdraw3.addActionListener(new ButtonListener());

    deposit = new JButton("Deposit");
    deposit.addActionListener(new ButtonListener());

    quit = new JButton("Quit");
    quit.addActionListener(new ButtonListener());

    num0 = new JButton("0");
    num0.addActionListener(new ButtonListener());

    num1 = new JButton("1");
    num1.addActionListener(new ButtonListener());

    num2 = new JButton("2");
    num2.addActionListener(new ButtonListener());

    num3 = new JButton("3");
    num3.addActionListener(new ButtonListener());

    num4 = new JButton("4");
    num4.addActionListener(new ButtonListener());

    num5 = new JButton("5");
    num5.addActionListener(new ButtonListener());

    num6 = new JButton("6");
    num6.addActionListener(new ButtonListener());

    num7 = new JButton("7");
    num7.addActionListener(new ButtonListener());

    num8 = new JButton("8");
    num8.addActionListener(new ButtonListener());

    num9 = new JButton("9");
    num9.addActionListener(new ButtonListener());

    clear = new JButton("Clear");
    clear.addActionListener(new ButtonListener());

    enter = new JButton("Enter");
    enter.addActionListener(new ButtonListener());


    // Allows the labels and JButtons to appear when compiled


    add(TextLabel);
    add(InputDisplay);

    add(withdraw1);
    add(num1);
    add(num2);
    add(num3);

    add(withdraw2);
    add(num4);
    add(num5);
    add(num6);

    add(withdraw3);
    add(num7);
    add(num8);
    add(num9);

    add(deposit);
    add(num0);
    add(clear);
    add(enter);
    add(quit);

    // Background and window dimension sizes
    setBackground(Color.gray);
    setPreferredSize(new Dimension(720, 300));


}

//代表按钮推送（动作）事件的监听器。公共类ButtonListener实现ActionListener

{ //按下按钮时更新计数器和标签。 public void actionPerformed（ActionEvent事件） { total =“”;

        Balance = 100;

        if(event.getSource() == num0)
        Input += "0";


        if(event.getSource() == num1)
        Input += "1";


        if(event.getSource() == num2)
        Input += "2";

        if(event.getSource() == num3)
        Input += "3";

        if(event.getSource() == num4)
        Input += "4";

        if(event.getSource() == num5)
        Input += "5";

        if(event.getSource() == num6)
        Input += "6";

        if(event.getSource() == num7)
        Input += "7";

        if(event.getSource() == num8)
        Input += "8";

        if(event.getSource() == num9)
        Input += "9";

        InputDisplay.setText(" " + Input);

        if(Input.equals("7777") && event.getSource() == enter)
        do
        {
        Input ="";
        TextLabel.setText("Your balance is " + Balance);

        }
        while ( event.getSource() != quit);

        TextLabel.setText("Goodbye.");


 }

Answer 1

您正在使用while ( event.getSource() != quit);阻止事件调度线程，这不是事件驱动框架的工作方式，事件发生，您回复，这就是它。

ETD负责处理和调度事件队列中的事件，ETD已通知注册到您的按钮的ActionListener，但在actionPerformed方法存在之前，它无法继续处理事件队列，它使你的程序看起来有＆＃34;挂起＆＃34;，因为它有。

删除while循环

基本上，您不需要while循环，但在调用if时需要额外的quit语句来检查actionPerformed按钮

Answer 2

你的框架冻结的原因很简单：你阻止事件调度线程（某些点上的所有挥动事件都通过这个线程），所以你阻止程序处理任何其他事件，因此框架冻结。由于while循环是一个endlessloop（你只输入while循环，如果满足循环的条件，并且event.getSource()的结果不会改变），你的帧会冻结。对于SwingWorker：

public void actionPerformed(final ActionEvent e){
    new SwingWorker<String , Object>(){
         public String doInBackground(){
              //create String for the label
              return labelText;
         }

         public void done(){
             TextLabel.setText(get());
         }
    }.execute();
}

会创建并执行SwingWorker，但这对于像您这样简单快速完成的任务来说并不是必需的。只需删除endlessloop。

按下按钮时Jframe冻结

2 个答案: