Question

我有一个带有Actionlistener的JTextField。现在，当我按回车键时，我希望它可以做某些事情。我正在使用共享的ActionListener，因此尝试在JTextField上执行getSource但它不起作用！希望任何人都可以提供帮助。

JTextField txtProductAantal = new JTextField(String.valueOf(WinkelApplication.getBasket().getProductAmount(productdelete)));
            txtProductAantal.setBounds(340, verticalPosition + i * productOffset, 40, 20);
            txtProductAantal.addActionListener(this);
            add(txtProductAantal); 

public void actionPerformed(ActionEvent event) {

        if (event.getSource() == btnEmptyBasket) {
            WinkelApplication.getBasket().empty();
            WinkelApplication.getInstance().showPanel(new view.CategoryList());
        }

        if(event.getSource() == txtProductAantal){
            String productgetal = txtProductAantal.getText();
            txtProductAantal.setText(productgetal);
            WinkelApplication.getInstance().showPanel(new view.Payment());
        }
    }

Answer 1

必须为比较创建临时Object

例如

   public void actionPerformed(ActionEvent event) {
        Object source = event.getSource();
        if (source == btnEmptyBasket) {
           //...........
        } else if (source == txtProductAantal) {
           //........... 
        } else {

        }
    }

或只有JTextFields（在instanceof语句中避免if - else）您可以直接将对象转换为JTextField

JTextField source = (JTextField) event.getSource();

编辑，

one from the next adviced 17 problems.
please to read suggestion by @Andrew Thompson, again
- 1) For better help sooner, post an SSCCE.
- 2) txtProductAantal.setBounds(..)
- Use layouts to avoid the next 17 problems.

我的代码按预期工作

import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JTextField;

public class JTextFieldAndActionListener implements ActionListener {

    private JFrame frm = new JFrame("JTextFieldAndActionListener");
    private JTextField one = new JTextField(10);
    private JTextField two = new JTextField();
    private JTextField three = new JTextField();

    public JTextFieldAndActionListener() {
        one.addActionListener(this);
        two.addActionListener(this);
        three.addActionListener(this);
        frm.setLayout(new GridLayout());
        frm.add(one);
        frm.add(two);
        frm.add(three);
        frm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frm.setLocation(400, 300);
        frm.pack();
        frm.setVisible(true);
    }

    public void actionPerformed(ActionEvent event) {
        Object source = event.getSource();
        if (source == one) {
            System.out.println("firing from JTextField one");
        } else if (source == two) {
            System.out.println("firing from JTextField two");
        } else if (source == three) {
            System.out.println("firing from JTextField three");
        } else {
            System.out.println("something went wrong");
        }
    }

    public static void main(String[] args) {

        javax.swing.SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                JTextFieldAndActionListener ie = new JTextFieldAndActionListener();
            }
        });
    }
}

按ENTER键打印输出

run:
firing from JTextField one
firing from JTextField two
firing from JTextField three
BUILD SUCCESSFUL (total time: 15 seconds)

输入密钥JTextField

1 个答案: