JAVA Swing组件不会显示

Question

For some reason some of the Swing components don't show up when I run the program and I can't figure out why. Only the multiply label, multiply button, total label, and stop button show up. The rest don't work.

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

public class BabyCalculatorFinal extends JFrame{

private JLabel AdditionLabel;
private JTextField AdditionField;
private JButton AdditionButton;
private JPanel Multiplication;
private JLabel MultiplicationLabel;
private JTextField MultiplicationField;
private JButton MultiplicationButton;
private JPanel Total;
private JLabel TotalLabel;
private JTextField TotalField;
JButton StopButton;

public BabyCalculatorFinal(){
    setDefaultCloseOperation(EXIT_ON_CLOSE);// 1st thing to do
    setName("Baby Calculator Final"); // 2nd thing to do
    setLayout(new GridLayout(3,0)); //sets grid layout for the entire thing with 3 rows
    // Create Action Event
    BabyCalculatorListener Listener = new BabyCalculatorListener();
    //Addition 
    //Addition Set Layout
    JPanel Addition = new JPanel(new BorderLayout());
    //Addition Features
    AdditionLabel = new JLabel("Amount to add"); //Create label
    AdditionField = new JTextField(10);
    AdditionButton = new JButton("Add");
    //Organize Addition Panel
    Addition.add(AdditionLabel, BorderLayout.WEST);//IMPORTANT FORMAT
    Addition.add(AdditionLabel, BorderLayout.CENTER);
    Addition.add(AdditionButton, BorderLayout.EAST);
    //Add addition Panel to Frame
    add(Addition);
    AdditionButton.addActionListener(Listener);

    //Multiplictation
    //Multiplication Set Layout
    Multiplication = new JPanel();
    Multiplication.setLayout(new BorderLayout());//Trying a different way of setting the layout
    //Multiplication Features
    MultiplicationLabel = new JLabel("Amount to Multiply"); //Create label
    MultiplicationField = new JTextField(10);
    MultiplicationButton = new JButton("Multiply");
    //Organize Multiplication Panel
    Addition.add(MultiplicationLabel, BorderLayout.WEST);
    Addition.add(MultiplicationLabel, BorderLayout.CENTER);
    Addition.add(MultiplicationButton, BorderLayout.EAST);
    //Add Multiplication Panel to Frame
    add(Multiplication);
    MultiplicationButton.addActionListener(Listener);
    //Total
    Total = new JPanel(new FlowLayout(10));
    TotalLabel = new JLabel("Total");
    TotalField = new JTextField();
    TotalField.setText("0.0");
    TotalField.setVisible(false);
    StopButton = new JButton("Stop");
    Total.add(TotalLabel);
    Total.add(TotalField);
    Total.add(StopButton);
    //Add Total Panel to Frame
    add(Total);
    pack();
    setVisible(true);
}

public static void main(String[] args){
    JFrame myFrame = new BabyCalculatorFinal();
}

public class BabyCalculatorListener implements ActionListener{
    public void actionPerformed(ActionEvent e){
        String totalText = TotalField.getText();
        double total = Double.parseDouble(totalText);
        if (e.getSource() == AdditionButton){
        String additionText = AdditionField.getText();
        double addition = Double.parseDouble(additionText);
        total += addition;
       }
       else{
           String multiplicationText = MultiplicationField.getText();
           double multiplication = Double.parseDouble(multiplicationText);
           total += multiplication;
        }
        TotalField.setText(total + "");
    }
}

}

Answer 1

Your code is full of typos (?), for example you're adding AdditionLabel twice to the JPanel instead of adding AdditionLabel and AdditionField . And you're not using the Multiplication panel after creating it but instead overriding the contents of the Addition panel. The corrected snippet that adds the components should be (I changed the variable names to conform to Java conventions):

additionLabel = new JLabel("Amount to add"); // Create label
additionField = new JTextField(10);
additionButton = new JButton("Add");
// Organize addition Panel
addition.add(additionLabel, BorderLayout.WEST);// IMPORTANT FORMAT
addition.add(additionField, BorderLayout.CENTER); // instead of additionLabel
addition.add(AdditionButton, BorderLayout.EAST);
// Add addition Panel to Frame
add(addition);
AdditionButton.addActionListener(Listener);

// Multiplictation
// Multiplication Set Layout
multiplication = new JPanel();
multiplication.setLayout(new BorderLayout());// Trying a different way
                                                // of setting the layout
// Multiplication Features
multiplicationLabel = new JLabel("Amount to Multiply"); // Create label
multiplicationField = new JTextField(10);
multiplicationButton = new JButton("Multiply");
// Organize Multiplication Panel
multiplication.add(multiplicationLabel, BorderLayout.WEST);   // instead of Addition
multiplication.add(multiplicationField, BorderLayout.CENTER);
multiplication.add(multiplicationButton, BorderLayout.EAST);