java - GUI Java-如何使用2个用户输入的数字来得到答案

Question

我正在尝试构建一个百分比程序，用于查找一个数字与另一个数字的百分比。我想为 jtextfield 获取两个用户输入的数字，点击 jbutton 并将答案显示在作为结果列出的另一个 jtextfield 中。知道如何做到这一点，我知道它需要 Action 监听器，但我不知道从那里去哪里。这是我所拥有的，我可以用它打印出我想要的内容，只是不知道必须让 Action 监听器工作。

package GUI;

import javax.swing.*;

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


@SuppressWarnings("serial")
public class WeightGUI  extends JFrame{
private JLabel label1;
private JTextField field1;
private JLabel label2;
private JTextField field2;
private JLabel label3;
private JTextField field3;
private JLabel label4;
private JTextField field4;
private JButton button1;
private JButton button2;
private JButton button3;
public WeightGUI () {
    super( "Percentage Weight Loss Calculator");
    setLayout( new FlowLayout() );

    label1 = new JLabel ("Starting Weight ");
    field1 = new JTextField ("Type");
    label2 = new JLabel ("Last Week Weight");
    field2 = new JTextField ("Type");
    label3 = new JLabel ("Current Weight");
    field3 = new JTextField ("Type");
    label4 = new JLabel ("Percentage Lost");
    field4 = new JTextField ("Results");
    button1 = new JButton (" Calculate Percent Total");
    button2 = new JButton (" Calculate Percent Week");
    button3 = new JButton (" Calculate Percent from last weight");
    label1 = new JLabel( "Starting Weight");
    add(label1);

    field1 = new JTextField("Type");
    add (field1);

    label2 = new JLabel( "Last Week Weight");
    add(label2);

    field3 = new JTextField(10);
    add (field2);

    label3 = new JLabel( "Current Weight");
    add(label3);

    field3 = new JTextField("Type");
    add (field3);

    label4 = new JLabel( "Percentage Lost");
    add( label4 );

    field4 = new JTextField("Results");
    field4.setEditable(false);
    add (field4);

    button1 = new JButton ("Calculate Total Percent");
    add( button1 );

    button2 = new JButton ("Calculate Percent from last Weight");
    add( button2 );

    button3 = new JButton ("Calculate Weekly Percent");
    add( button3 );

    thehandler handler = new thehandler();
    button1.addActionListener(handler);

    thehandler handler1 = new thehandler();
    button2.addActionListener(handler1);

    thehandler handler2 = new thehandler();
    button3.addActionListener(handler2);
}

private class thehandler implements ActionListener {

    public void actionPerformed (ActionEvent e){

        int sw;
        int lw;
        int cw;
        double weight = 0 ;
        String inputString;
        inputString = field1.getText();
        inputString = field2.getText();
        inputString = field3.getText();
        sw = Integer.parseInt(inputString);
        lw = Integer.parseInt(inputString);
        cw = Integer.parseInt(inputString);
            if(e.getSource() == button1) {
                weight = (sw - cw) / sw;
            }
            else if(e.getSource() == button2) {
                weight = (lw - cw) / sw;
            }
            else if(e.getSource() == button3){
                weight = (lw - cw)/ lw;



    }



    }
}


}

Answer 1

您的代码的主要问题是您没有设置保存结果的 JTextField 的文本。只需在此 JTextField 上调用 setText(...) 并传入表示结果的字符串即可完成此操作。您还需要删除 JTextFields 中的无意义文本“Type”，因为它们可能会把事情搞砸，除非您想向所有文本字段添加 FocusListener，以便在 focusGained 上它将选择该字段的所有内容。

您还需要按照我上面的评论中所述重新命名变量。