Question

用户在文本字段中输入数字并单击按钮后，我想在另一个文本字段中返回该值，我不确定我需要哪个类，有什么提示吗？非常感谢你，这是我的代码：

private void newNumber(Container container){
    JPanel panel = new JPanel(new GridBagLayout());
    GridBagConstraints constraint = new GridBagConstraints();
    //add the new number
    labelname = new JLabel("Enter the number: ");
    constraint.gridx = 0;
    constraint.gridy = 0;
    panel.add(labelname, constraint);

    number= new JTextField(10);
    constraint.gridx = 1;
    constraint.gridy = 0;
    panel.add(number, constraint);

    addnumber = new JButton("Add number");
    constraint.gridx = 0;
    constraint.gridy = 3;
    panel.add(addnumber, constraint);

    container.add(panel,"North");

}

我知道它应该有一个关于ActionListener的方法，但我仍在弄清楚它：）

Answer 1

基本上，您为按钮分配一个ActionListener，以便对click事件做出反应。在此侦听器中，您将获得文本字段的值并将其分配给其他字段。

JButton yourButton= new JButton("Click me");
JTextField textField = new JTextField("Some initial value Textfield 1");
JTextField textField2 = new JTextField("Some initial value Textfield 2");
yourButton.addActionListener(new ActionListener()
{
  public void actionPerformed(ActionEvent e)
  {
    // Get value of textfield 1
     String currValue = textField.getText();
    // Set value for textfield 2
    textField2.setText(currValue); 
  }
});

Answer 2

public class FramTest extends JFrame{

    public static void main(String[] args){
        FramTest framTest = new FramTest();

        JPanel panel = new JPanel(new GridBagLayout());
        //add the new number
        JLabel labelname = new JLabel("Enter the number: ");
        panel.add(labelname);

        final JTextField number= new JTextField(10);

        panel.add(number);

        JButton addnumber = new JButton("Add number");
        panel.add(addnumber);

        final JTextField numberright= new JTextField(10);
        addnumber.addActionListener(new ActionListener() {

            public void actionPerformed(ActionEvent e) {
                numberright.setText(number.getText());

            }
        });

        panel.add(numberright);
        framTest.add(panel);

        framTest.show();
    }
}

Answer 3

您必须向按钮添加ActionListener，并且在侦听器中，您可以添加对新方法的调用以执行所需的操作。我假设您想从文本字段“number”获取文本，并且您希望在名为“secondTextfield”的第二个文本字段中写入该值。

// Add the lister to the button
addnumber.addActionListener(new java.awt.event.ActionListener() {
    public void actionPerformed(java.awt.event.ActionEvent evt) {
        // Call a function to perform the action
        setTheText(evt);
    }
});

// Function to set the text
private void setTheText(java.awt.event.ActionEvent evt) {
     secondTextfield.set(number.getText());
}

如何直接在java中返回输入？

3 个答案: