Eclipse中的JButton：“按钮无法解析或不是字段”

New to Java and this Page. I am trying to perfom a certain action when a JButton is pressed. Following this tutorial (in German, sorry) http://www.java-tutorial.org/actionlistener.html, I used the JFrame Design feature and added content afterwards:

Java和本页新手。我试图在按下JButton时执行某个动作。按照本教程(德语,抱歉)http://www.java-tutorial.org/actionlistener.html,我使用了JFrame Design功能并在之后添加了内容:

public class JFrame extends javax.swing.JFrame implements ActionListener
{

private JPanel contentPane;

/**
 * Launch the application.
 */
public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
        public void run() {
            try {
                JFrame frame = new JFrame();
                frame.setVisible(true);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
}

/**
 * Create the frame.
 */
public JFrame()
{

    this.setTitle("BMS Anpassen");

    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setBounds(100, 100, 450, 300);
    contentPane = new JPanel();
    contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
    setContentPane(contentPane);
    contentPane.setLayout(null);

    JButton btnFlush = new JButton("Flush!");
    btnFlush.setBounds(170, 209, 89, 23);
    contentPane.add(btnFlush);

    JSpinner spinner = new JSpinner();
    spinner.setToolTipText("Gib die Spannung ein!");
    spinner.setModel(new SpinnerNumberModel(new Float(3000), new Float(2700), new Float(4100), new Float(100)));
    spinner.setBounds(56, 49, 52, 20);
    contentPane.add(spinner);

    JLabel lblMv = new JLabel("mV");
    lblMv.setFont(new Font("Tahoma", Font.PLAIN, 13));
    lblMv.setBounds(113, 51, 24, 14);
    contentPane.add(lblMv);

    JButton btnSetParameters = new JButton("Set Parameters");
    btnSetParameters.setBounds(152, 175, 130, 23);
    contentPane.add(btnSetParameters);

    //Buttons dem Listener zuordnen
    btnFlush.addActionListener(this);
    btnSetParameters.addActionListener(this);

}

public void actionPerformed(ActionEvent ae){

    if(ae.getSource() == this.btnSetParameters){

    // Parameter in Config schreiben/Write parameters in Config
    FileWriter fw = new FileWriter("ConfigBMS.txt");
    BufferedWriter bw = new BufferedWriter(fw);

    bw.write("25000");
    bw.newLine();
    bw.write("42000");
    bw.newLine();
    bw.write("27000");
    bw.newLine();
    bw.write("41000");

    bw.close();
    }
    else
    {           
    }
}

}

It now gives me the errormessage "btnSetParameters cannot be resolved or is not a field". Reading through other posts on JButtons here didn't help me or I didn't understand it. I feel like the this in if(ae.getSource() == this.btnSetParameters){ is the problem, but I can't find a way to fix it.

它现在给我错误消息“btnSetParameters无法解析或不是字段”。阅读JButtons上的其他帖子对我没有帮助,或者我不理解它。我觉得if(ae.getSource()== this.btnSetParameters){是问题,但我无法找到修复它的方法。

Any push in the right direction is greatly appreciated and thank you in advance,

非常感谢任何正确方向的推动,并提前感谢您,

Oli

2 个解决方案

#1

you have an scope issue, btnSetParameters must be declared as a Frame member field

如果存在范围问题,则必须将btnSetParameters声明为Frame成员字段

public class JFrame extends javax.swing.JFrame implements ActionListener {
    private JButton btnSetParameters;

and no inside the constructor, use the constructor instead to initialize the button!

并且不在构造函数内部,而是使用构造函数来初始化按钮!

public JFrame() {
    .... 
    btnSetParameters = new JButton("Set Parameters");
}

#2

You have to make the the JButton btnSetParameters a field of the class - currently it's just in the context of the constructor.

你必须使JButton btnSetParameters成为类的一个字段 - 目前它只是在构造函数的上下文中。

#1