Question

我正在创建GUI程序称为KwH计算器，它的作用是计算某个项目的耗电量，所以我的问题是在组合框中，我想要的是如果用户在选择中选择一个项目瓦特将自动出现功耗（powTF）。

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

public class KwH extends JFrame{
    private  JComboBox appCB;
    private  JLabel appL,powL,unitL,wattsL,hrL,hoursL,dayL,monthL,yearL,kwhdayL,kwhmonthL,kwhyearL;
    private  JTextField appTF,powTF,hoursTF,dayTF,monthTF,yearTF;
    private  JButton calculateB,exitB,resetB;
    private  CalculateButtonHandler cbHandler;
    private  ExitButtonHandler exitHandler;
    private  ResetButtonHandler resetHandler;
    private String[] appStrings={" ","Refrigirator","Electric Iron","Fan","Television","Washing Machine"};

public KwH(){


    appCB=new JComboBox(appStrings);
    appL=new JLabel ("Appliances: ",SwingConstants.LEFT);
    powL=new JLabel ("Power Consumption: ",SwingConstants.LEFT);
    hoursL=new JLabel ("Hours of Use: " ,SwingConstants.LEFT);
    unitL=new JLabel (" ",SwingConstants.LEFT);
    wattsL=new JLabel ("Watts",SwingConstants.LEFT);
    hrL=new JLabel("hr/day",SwingConstants.LEFT);
    dayL=new JLabel ("Energy Consumed per Day: ",SwingConstants.LEFT);
    monthL=new JLabel("Energy Consumed per Month: ",SwingConstants.LEFT);
    yearL=new JLabel("Energy Consumed per Year: ",SwingConstants.LEFT);
    kwhdayL=new JLabel("kwh/day" ,SwingConstants.LEFT);
    kwhmonthL=new JLabel("kwh/month",SwingConstants.LEFT);
    kwhyearL=new JLabel("kwh/year", SwingConstants.LEFT);


    appTF=new JTextField(10);
    powTF=new JTextField(10);
    hoursTF=new JTextField(10);
    dayTF=new JTextField(10);;
    monthTF=new JTextField(10);
    yearTF=new JTextField(10);


    calculateB=new JButton("Calculate");
    cbHandler=new CalculateButtonHandler();
    calculateB.addActionListener(cbHandler);

    exitB=new JButton("Exit");
    exitHandler=new ExitButtonHandler();
    exitB.addActionListener(exitHandler);

    resetB=new JButton("Reset");
    resetHandler=new ResetButtonHandler();
    resetB.addActionListener(resetHandler);


    setVisible(true);
    setTitle("KwH Calculator");
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    setSize(600,600);

    Container p=getContentPane();
    p.setLayout(new GridLayout(7,3));


    p.add(appL);
    p.add(appCB);
    p.add(unitL);
    p.add(powL);
    p.add(powTF);
    p.add(wattsL);
    p.add(hoursL);
    p.add(hoursTF);
    p.add(hrL);
    p.add(calculateB);
    p.add(exitB);
    p.add(resetB);
    p.add(dayL);
    p.add(dayTF);
    p.add(kwhdayL);
    p.add(monthL);
    p.add(monthTF);
    p.add(kwhmonthL);
    p.add(yearL);
    p.add(yearTF);
    p.add(kwhyearL);


}

public class CalculateButtonHandler implements ActionListener{
    public void actionPerformed(ActionEvent e){

        double a,b,c,d,f,g,h;

        a=Double.parseDouble(powTF.getText());
        b=Double.parseDouble(hoursTF.getText());


        c=(a*b)/1000;
        d=c*30;
        f=d*12;

        dayTF.setText(""+c);
        monthTF.setText(""+d);
        yearTF.setText(""+f);


    }
}

public class ResetButtonHandler implements ActionListener{
    public void actionPerformed (ActionEvent e){

    }
}

public class ExitButtonHandler implements ActionListener{
    public void actionPerformed(ActionEvent e){
        System.exit(0);
    }
}

public static void main(String[]args){

    KwH p=new KwH();
}

}

Answer 1

如右图所示，用户仍然需要输入功耗。保持当前的设计，添加一系列功耗值：

private String[] appStrings={" ","Refrigirator","Electric Iron","Fan","Television","Washing Machine"};
private double[] appPower={0.0, 200.0, 50.0, 20.0, 150.0, 250.0};  // New

将ActionChangeListener添加到组合框：

appCB.addActionListener(new ApplianceChangeListener());

由于您有查找表，因此您可能不希望用户编辑功耗。如果是这种情况，您可能希望将该字段设置为不可编辑：

powTF.setEditable(false);

为了使“计算”按钮保持工作并添加功能，我建议将CalculateButtonHandler中的所有代码移动到名为calculate的新方法中，然后让按钮处理程序调用计算。

public class CalculateButtonHandler implements ActionListener{
    public void actionPerformed(ActionEvent e){
        calculate();
    }
}

private void calculate() {
    double a,b,c,d,f,g,h;

    try {
        a=Double.parseDouble(powTF.getText());
        b=Double.parseDouble(hoursTF.getText());
    } catch (NumberFormatException nfe) {
        return;
    }

    c=(a*b)/1000;
    d=c*30;
    f=d*12;

    dayTF.setText(""+c);
    monthTF.setText(""+d);
    yearTF.setText(""+f);

}

请注意，对parseDouble的调用有一个try / catch包装器。如果用户没有输入小时或者他们没有选择任何设备，这将从方法返回（没有错误）。

最后，还有ApplianceChangeListener：

public class ApplianceChangeListener implements ActionListener {

    @Override
    public void actionPerformed(ActionEvent ae) {
        int item = appCB.getSelectedIndex();

        if (item == 0) powTF.setText("");
        else powTF.setText("" + appPower[item]);

        calculate();
    }
}

JComboBox增加了价值

1 个答案: