java - 在 Java 中向按钮添加 ActionListener

Question

我试图了解如何在单击按钮后打印信息。我尝试过很多事情，但我正在自己学习。我目前正在了解不同的监听器，因此请帮助我添加按钮监听器。

我希望当选择组合框时它会打印出信息并显示一些详细信息。我有一个按钮，但我希​​望一旦选择了组合框中的信息，它就会打印出信息。

import javax.swing.*;
import java.awt.Color;
import java.awt.Component;
import java.awt.event.*;

public class ItemCheck extends JFrame{

    JComboBox PainandFeverReliever;
    JButton button1;
    JLabel lable;

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

    public ItemCheck(){
        this.setSize(400,400);

        this.setLocationRelativeTo(null);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        this.setTitle("Medicine Stock");

        JPanel thePanel = new JPanel();
        JLabel label = new JLabel (" Medicine");
        label.setToolTipText("This Shows you how many medicine you have left in the store.");
        thePanel.add(label);

        String[] shows = {"","Cetaminophen" , "ephedrine","menthol"};

        PainandFeverReliever = new JComboBox(shows);
        PainandFeverReliever.addItem("Pushing Daisies");

        thePanel.add(PainandFeverReliever);

        button1 = new JButton("Results");

        ListenForButton lForButton = new ListenForButton();

        button1.addActionListener(lForButton);
        thePanel.add(button1);

        this.add(thePanel);

        this.setVisible(true);

        PainandFeverReliever.insertItemAt("diphenhydramine", 1);

        PainandFeverReliever.setMaximumRowCount(20);
    }

    private void setForeground(int hsBtoRGB) {
        // TODO Auto-generated method stub
    }

    private class ListenForButton implements ActionListener{
        public void actionPerformed(ActionEvent e){
            if(e.getSource() == button1){
            }
        }
    }
}

Answer 1

如果我理解正确的话，您想知道如何向组合框添加监听器。您可以使用与按钮类似的方式来完成此操作。对于 PainandFeverReliever 组合框，您可以在创建它后添加此代码(假设您使用的是 Java 8 或更高版本):

PainandFeverReliever.addActionListener(
        actionEvent -> System.out.println("Selected medicine: "
                                + PainandFeverReliever.getSelectedItem())
);