当textField位于不同的面板中时，textField.getText（）不工作（与Button.AddActionListener相比）

Question

（4）调用Button.AddActionListener（...）并使用jTextField.getText（）

下面是我的代码：

package GUI;
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class aaaaa {

// Class attributes
// Overall class attributes
private JFrame frame = new JFrame("Simulation App");
    
// Class attributes for method setTextFieldPar
private JPanel panelThetaCh = new JPanel();
private JPanel panelSetButton = new JPanel();

private JTextField textFieldThetaCh = new JTextField();

private String StringThetaCh;

// Class attributes for method setButton
private JButton buttonSetPar;

// ========================================================================================================================
// Class methods

// Text field of all simulation parameters
public void setTextFieldPar(JPanel panel, JTextField textField, String latexString){
    // Panel layout - FlowLayout
    panel.setLayout(new FlowLayout());
    panel.setMinimumSize(new Dimension(300, 100));
    frame.add(panel);
    panel.setAlignmentX(Component.CENTER_ALIGNMENT);
    
    JLabel labelText = new JLabel("text");
    panel.add(labelText);
    
    // Create text field        
    textField = new JTextField(13);
    panel.add(textField);
}


// Button "Set Parameters"
public void setButton (JPanel panel){
    panel.setLayout(new GridLayout(4, 0));
    panel.setMaximumSize(new Dimension(200, 100));
    frame.add(panel);
    panel.setAlignmentX(Component.CENTER_ALIGNMENT);
    
    buttonSetPar = new JButton("Set Parameters");
    panel.add(buttonSetPar);        
}   


// Monitor input in text field
public void monitorTextField() {
    buttonSetPar.addActionListener(new ActionListener() {
        public void actionPerformed (ActionEvent e) {
            // Extract numbers entered in text field for the parameters
            StringThetaCh = textFieldThetaCh.getText();
                
            if (StringThetaCh.equals("")) {
                JFrame errorWindow = new JFrame("Error");
                errorWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                errorWindow.setLocationRelativeTo(null);
                
                JOptionPane.showMessageDialog(errorWindow, "At least one text field is empty, please enter numerical values");
            }
        }
    });
}


// Constructor
public aaaaa(){
    frame.setSize(350, 800);
    frame.setDefaultCloseOperation(JFrame.HIDE_ON_CLOSE);
    frame.setLocationRelativeTo(null);
    frame.setLayout(new BoxLayout(frame.getContentPane(), BoxLayout.Y_AXIS));
    
    // Text field for parameters
    setTextFieldPar(panelThetaCh, textFieldThetaCh, "\\theta_{CH}");

    // Button for set parameter
    setButton(panelSetButton);
    
    // Monitoring input in text field
    monitorTextField();
    
}


public static void main(String args[]) {
    EventQueue.invokeLater(new Runnable() {    
        public void run() {    
            aaaaa window2 = new aaaaa();
            window2.frame.setVisible(true);
        } 
    });
}

}

Answer 1

您已经在类声明中创建了文本字段：

private JTextField textFieldThetaCh = new JTextField();

然后将其传递给方法SettextFieldPar，并在其中创建另一个添加到面板中的文本字段：

textField = new JTextField(13);
panel.add(textField);

因此，类变量TextFieldTheTach不是添加到面板中的变量，因此用户无法访问。

只需在SettextFieldPAR中删除新文本字段的创建，它就可以工作了。

下面是正在发生的事情的可视化表示：

1. 在类声明中: