Question

我是编程的新手，正在寻找有关如何在下面的代码中向我的lblScenario（我制作的标签）显示我的问题的建议。我使用的技术不起作用任何帮助将不胜感激：}

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;


public class MoralGameGUI 
{
    private JLabel lblScenario;
    private JFrame frame;
    private JPanel panel;
    int score;



    public MoralGameGUI()
    {
        frame=new JFrame();
        frame.setTitle("Moral Game");
        frame.setSize(500,500);
        frame.setLocationRelativeTo(null);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JButton btnYes = new JButton("Yes");
        frame.getContentPane().add(btnYes, BorderLayout.WEST);


        JButton btnNo = new JButton("No");
        frame.getContentPane().add(btnNo, BorderLayout.EAST);

        JButton btnGetScenario = new JButton("Get Scenario ");
        btnGetScenario.addActionListener(new ScenarioHandler());
        frame.getContentPane().add(btnGetScenario, BorderLayout.NORTH);

        JLabel lblScenario = new JLabel("Scenario");
        frame.getContentPane().add(lblScenario, BorderLayout.CENTER);


        JLabel lblAnswer = new JLabel("answer");
        frame.getContentPane().add(lblAnswer, BorderLayout.SOUTH);
        panel= new JPanel();
        panel.setLayout(null);
        frame.setVisible(true);

    }


    class ScenarioHandler implements ActionListener
    {
        public void actionPerformed(ActionEvent event)
        {

    int index = (int)(Math.random()*20);

            if (index == 2){
                lblScenario.setText("nd save her?");
            }
            else if (index ==3){    
                lblScenario.setText("A magic evil gene asks you if you would give up all your fingers and toes to help raise funds for a ugandan princess");
            }

            else if (index ==4){
                lblScenario.setText("A woman with a rubbish dress on ask you for yours do you give it to her ");
            }
            else if (index ==5){
                lblScenario.setText("A man with no shoes asks for your hand in marriage what do you say");
            }
            else if (index ==6){
                lblScenario.setText("your stuck in a derilict prison and you find a loaf of bread in the darkness do you eat it ");
            }
            else if (index ==7){
                lblScenario.setText("The jam has a thick layer of mould over it do you eat it?");
            }
            else if (index ==8){
                lblScenario.setText("15 giant racoons try to stral your humous what do you shout out them");
            }
            else if (index ==9){
                lblScenario.setText("your wedding dress has been lost do you buy some sweet reeboks instead");
            }
            else if (index ==10){
                lblScenario.setText("ten lizards attack do you fight back");
            }
            else if (index ==11){
                lblScenario.setText("there is no bread left in the kitchen do you cry?");
            }
            else if (index ==12){
                lblScenario.setText("do you sell your soul for a delicious pack of oreos");
            }
            else if (index ==13){
                lblScenario.setText("Have you got a mans voice");
            }
            else if (index ==14){   
                lblScenario.setText("have you got the heart of a lion");
            }

            else if (index ==15){   
                lblScenario.setText("no eyebrowns dosent hold you back do you agree?");
            }

            else if (index ==16){
                lblScenario.setText("spiders come do you stand your ground");
            }
            else if (index ==17){
                lblScenario.setText(" or no?");
            }
            else if (index ==18){
                lblScenario.setText("are you old?");
            }
            else if (index ==19){   
                lblScenario.setText("......?");
            }
            else if (index ==20){
                lblScenario.setText(".........?");
            }





        }
    }
    public static void main(String[] args)
    {
        new MoralGameGUI();
    }
}

class YesNoHandler implements ActionListener
{
    public void actionPerformed(ActionEvent event)
    {



    }
}

忽略拼写错误并再次感谢：）

Answer 1

在MoralGameGUI()中，您将重新声明一个与实例变量同名的新JLabel对象（保留null，并在您调用方法时导致崩溃，像setText）：

JLabel lblScenario = new JLabel("Scenario");

只需这样做，将值分配给真实的：

lblScenario = new JLabel("Scenario");

Answer 2

在您的构造函数中，您执行：

JLabel lblScenario = new JLabel("Scenario");

因此，您创建新的JLabel ，而不是初始化原始。因此，这个新的JLabel会添加到您的框架中。但是，在actionPerformed方法中，这个新的JLabel不可见。它可以访问您之前声明的JLabel。但是，该方法不在您的JFrame中，因此无法对其进行任何更改。

因此你的尝试失败了。

你必须这样做：

lblScenario = new JLabel("Scenario");

将文字显示到标签

2 个答案: