JTextField ActionListner가 RGB 변수를 변경하지 않습니다

Question

나는 Text 클래스의 변수 R, G, B를 변경할 수있는 프로그램을 만들려고합니다. 「SubmitR」버튼을 클릭 해 애플릿을 실행하려고하면 (자), thread AWT-EventQueue-1 java.lang.NullPointerException에 예외가 붙습니다.

public class Main extends JApplet { 
private ButtonHandlerR buttonHandlerR; 




@Override 
public void start() { 
    super.start(); 
} 


@Override 
public void init() { 


    this.setSize(750, 300); 

    setLayout(new BorderLayout()); 

    add(new SetTextColour(), BorderLayout.NORTH); 
    add(new Text(),BorderLayout.CENTER); 






} 

}

public class SetTextColour extends JPanel { 


private JLabel labelR; 
private JLabel labelG; 
private JLabel labelB; 

public JTextField textR; 
public JTextField textG; 
public JTextField textB; 

public JButton submitR; 
public JButton submitG; 
public JButton submitB; 


public SetTextColour() { 

    labelR = new JLabel("RED: "); 
    labelG = new JLabel("GREEN: "); 
    labelB = new JLabel("BLUE: "); 

    textR = new JTextField(10); 
    textB = new JTextField(10); 
    textG = new JTextField(10); 


    add(textR, BorderLayout.NORTH); 
    submitR = new JButton("SubmitR"); 
    add(submitR, BorderLayout.NORTH); 

    add(textB, BorderLayout.NORTH); 

    submitG = new JButton("SubmitG"); 
    add(submitG, BorderLayout.NORTH); 

    add(textG, BorderLayout.NORTH); 

    submitB = new JButton("SubmitB"); 
    add(submitB, BorderLayout.NORTH); 

    ButtonHandlerB BHB = new ButtonHandlerB(); 
    ButtonHandlerG BHG = new ButtonHandlerG(); 
    ButtonHandlerR BHR = new ButtonHandlerR(this); 

    submitB.addActionListener(BHB); 
    submitR.addActionListener(BHR); 
    submitG.addActionListener(BHG); 


} 

}

public class ButtonHandlerR implements ActionListener { 
private SetTextColour colour; 
private Text text; 


ButtonHandlerR(Text change){ 
    this.text = change; 

} 

ButtonHandlerR(SetTextColour set){ 
    this.colour = set; 

} 






@Override 
public void actionPerformed(ActionEvent e) { 

    JButton Clicked = (JButton) e.getSource(); 
    double tempV; 
    int tempV2; 

    if(colour.submitR == Clicked){ 
     tempV = Double.parseDouble(colour.textR.getText()); 
     tempV2 = (int) tempV; 
     text.R = tempV2; 
     System.out.println(text.R); 
     text.repaint(); 


    } 



} 

}

public class Text extends JApplet { 
private String textField = "Welcome to CE203 Assignment 1 - Hassan Khan, 1404460"; 
public int R=50; 
private int G=32; 
private int B=54; 

public void start(){ 

} 





public void init(){ 




} 

public void paint (Graphics g) { 


    Color customColor = new Color(R, G, B); 

    g.setColor(customColor); 

    g.drawString(textField, 125, 150); 



} 

}

Answer 1

당신은해야하지 SwingUtilities.invokeLater 또는 SwingUtilities.invokeAndWait를 사용 하시겠습니까?

나는 얼마 동안 스윙을 사용하지 않았지만 이것은 나의 기억이다. 그것을 시도해 볼 수 있습니까? https://docs.oracle.com/javase/tutorial/uiswing/concurrency/initial.html