JTextField.getText() gibt Nullwert zurück und radiobuttons.isSelected() gibt immer

Question

2 verschiedene Fehler zurück, und ich habe keine Ahnung, was sie verursacht. Sie scheinen beide in den actionPerformed-Methoden zu sein. Dies sind 3 verschiedene Dateien, sorry für die schlechte Formatierung, ich kann es nie richtig funktionieren.

package A8; 

import javax.swing.*; 

import java.awt.*; 

public class a8main { 

public static final int RES_X = 600; 
public static final int RES_Y = 125; 

public static JFrame window; 
public static JPanel panel = new JPanel(); 
public static RatePanel ratePanel = new RatePanel(); 
public static MinutesPanel minutesPanel = new MinutesPanel(); 

public static void main(String[]args){ 
    createWindow(); 
    populateWindow(); 
} 

public static void createWindow(){ 
    window = new JFrame(); 
    window.setTitle("A8 Long Distance Communications"); 
    window.setSize(RES_X, RES_Y); 
    window.setEnabled(true); 
    window.setVisible(true); 
    window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
} 

public static void populateWindow(){ 
    ratePanel.populatePanel(panel); 
    minutesPanel.populatePanel(panel); 
    window.add(panel); 
} 

} 


package A8; 

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

import javax.swing.*; 

public class MinutesPanel implements ActionListener{ 

JTextField field = new JTextField(); 
JLabel minuteLabel = new JLabel(); 

int callTime; 
double chosenRate; 

public void populatePanel(JPanel Panel){ 
    createPanelObjects(); 
    Panel.add(minuteLabel); 
    Panel.add(field); 
} 

public void createPanelObjects(){ 
    chosenRate = RatePanel.chosenRate; 
    field.setColumns(10); 
    minuteLabel = new JLabel("Enter length of call in minutes"); 
    field.addActionListener(new MinutesPanel()); 
} 
public void displayCallPrice(){ 
    JOptionPane dialogBox = new JOptionPane(); 
    double cost = RatePanel.chosenRate * callTime; 
    dialogBox.showMessageDialog(null, "The cost of your call is $" + cost); 

} 

@Override 
public void actionPerformed(ActionEvent e) { 
    String callStr; 
    callStr = field.getText(); //problem is here. 
    //callStr = "3"; 
    System.out.print(callStr); 
    callTime = Integer.parseInt(callStr); 
    System.out.print(callTime); 
System.out.print(RatePanel.chosenRate); 

displayCallPrice(); 

} 

} 


package A8; 

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

import javax.swing.*; 

public class RatePanel implements ActionListener{ 

    public static final double DAY_RATE = 0.07; 
    public static final double EVENING_RATE = 0.12; 
    public static final double OFFPEAK_RATE = 0.05; 
    public static double chosenRate = DAY_RATE; //Because button defaults to day rate it is init to that rate. 

    JLabel categoryLabel = new JLabel(); 
    JRadioButton dayButton = new JRadioButton(); 
    JRadioButton eveningButton = new JRadioButton(); 
    JRadioButton offpeakButton = new JRadioButton(); 
    ButtonGroup buttons = new ButtonGroup(); 

    public void populatePanel(JPanel Panel){ 
     createPanelObjects(); 
     Panel.add(categoryLabel); 
     Panel.add(dayButton); 
     Panel.add(eveningButton); 
     Panel.add(offpeakButton); 
    } 

    public void createPanelObjects(){ 
     categoryLabel = new JLabel("Select a rate category"); 
     dayButton = new JRadioButton("Day rate: $" + DAY_RATE); 
     eveningButton = new JRadioButton("Evening rate: $" + EVENING_RATE); 
     offpeakButton = new JRadioButton("Offpeak rate: $" + OFFPEAK_RATE); 
     dayButton.setSelected(true); //Used to make it impossible to not select a rate, prevents bugs. 
     buttons.add(dayButton); 
     buttons.add(eveningButton); 
     buttons.add(offpeakButton); 
     dayButton.addActionListener(new RatePanel()); 
     eveningButton.addActionListener(new RatePanel()); 
     offpeakButton.addActionListener(new RatePanel()); 

    } 

    @Override 
    public void actionPerformed(ActionEvent e) { 
     if(dayButton.isSelected()){ 
      chosenRate = DAY_RATE; 
      System.out.println(DAY_RATE); 
     } 
     if(e.getSource() == eveningButton){ 
      chosenRate = EVENING_RATE; 
      System.out.println(EVENING_RATE); 
     } 
     if(e.getSource() == offpeakButton){ 
      chosenRate = OFFPEAK_RATE; 
      System.out.println(OFFPEAK_RATE); 
     } 
      System.out.println(e.getSource() == eveningButton); 
      System.out.println(dayButton.isSelected()); 
    } 


} 

Answer 1

Sie sollten nicht eine neue Instanz Ihrer ActionListener für jede Komponente erstellen.

Da Ihre Panels ActionListener implementieren, erstellen Sie jedes Mal, wenn Sie addActionListener() aufrufen, neue Instanzen von ihnen.

Statt dessen:

field.addActionListener(new MinutesPanel()); 

// ... 

eveningButton.addActionListener(new RatePanel()); 
offpeakButton.addActionListener(new RatePanel()); 

Sie sollten dies tun:

field.addActionListener(this); 

// ... 

eveningButton.addActionListener(this); 
offpeakButton.addActionListener(this);