一旦失去焦点，我想从文本字段中获取文本。 为此，我尝试使用“ this”运算符，但它不起作用

Question

i have a lot of textfields in my frame so it would be impossible to have a focus listener for each 1 of them. so i want to use a single focus listener function and get the text whenever the focus is lost.

        tf1=new JTextField();
        tf1.setBounds(200,300,150,50);
        tf1.setText("");
        tf1.addFocusListener(new java.awt.event.FocusAdapter() {
            public void focusLost(java.awt.event.FocusEvent evt) {
                tfFocusLost(evt);
            }
        });
        add(tf1);

        tf2=new JTextField();
        tf2.setBounds(200,500,150,50);
        tf2.setText("");
        tf2.addFocusListener(new java.awt.event.FocusAdapter() {
            public void focusLost(java.awt.event.FocusEvent evt) {
                tfFocusLost(evt);
            }
        });
        add(tf2);

    private void tfFocusLost(java.awt.event.FocusEvent evt) {
        s=this.getText();   
        System.out.println(s);
    }

Answer 1

Why not just creating your own class which extends FocusAdapter instead of creating an anonymous class for each of your JTextField :

public class MyFocusAdapter extends FocusAdapter {

    private final JTextField text;

    public MyFocusAdapter(JTextField text) {
        this.text = text;
    }

    public void focusLost(java.awt.event.FocusEvent evt) {
        System.out.println(text);
    }
}

Then you can use this class :

tf1.addFocusListener(new MyFocusAdapter(tf1));
tf2.addFocusListener(new MyFocusAdapter(tf2));

Answer 2

You will need to change the implementation for your tfFocusLost.

   private void tfFocusLost(java.awt.event.FocusEvent evt) {
        s=this.getText();   
        System.out.println(s);
    }

instead of above you can use something like this.

 private void tfFocusLost(java.awt.event.FocusEvent evt, JTextField textField ) {
        s=textField.getText();   
        System.out.println(s);
    }

And call it like tfFocusLost(evt,tf1);