/** * An extension to JButton that binds the button action to a Driver object, * which must feature a method called buttonPressed() * * @author M. Allen */ import javax.swing.*; import java.awt.event.*; @SuppressWarnings( "serial" ) public class EventButton extends JButton implements ActionListener { private Calculator calculator; /** * pre: Driver d must be instantiated && must contain a method called * buttonPressed(). * post: This button can respond to action events and run the Driver method * buttonPressed(). * * @param d Driver with which this button communicates. */ public EventButton( Calculator c ) { super(); addActionListener( this ); calculator = c; } /** * post: If this button is pressed, the driver method buttonPressed() is * called to respond to the button presss event. * * @param e : ActionEvent from associated objects */ public void actionPerformed( ActionEvent e ) { calculator.buttonPressed( this ); } }

这段代码是一个继承自JButton的类EventButton，它绑定了按钮的操作到一个Calculator对象上，并要求该对象具有名为buttonPressed()的方法。当按钮被按下时，将调用Calculator对象的buttonPressed()方法来响应按钮按下事件。这段代码实现了基本的MVC模式中的控制器部分。

相关问题

The ViewGetBook shows the text field called t (where the user can type text) and a button. Use a grid layout manager to position the two components.

Here's an example code snippet to achieve this using the grid layout manager:

import javax.swing.*;
import java.awt.*;

public class ViewGetBook extends JFrame {
    private JTextField textField;
    private JButton button;

    public ViewGetBook() {
        // Set up the frame
        setTitle("Get Book");
        setSize(300, 100);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        
        // Create the text field and button components
        textField = new JTextField();
        button = new JButton("Search");
        
        // Set up the grid layout manager
        setLayout(new GridLayout(1, 2));
        
        // Add the components to the frame
        add(textField);
        add(button);
        
        // Show the frame
        setVisible(true);
    }
    
    public static void main(String[] args) {
        ViewGetBook view = new ViewGetBook();
    }
}

In this code, we create a JFrame and set its title, size, and default close operation. We then create a JTextField and a JButton, and set up a grid layout manager with 1 row and 2 columns. We add the components to the frame, and then make it visible. When we run the program, we should see a frame with a text field and a button positioned side-by-side.

Button cannot be resolved to a type

这个错误提示是因为你在代码中使用了一个类型为 Button 的变量或方法，但是编译器无法找到这个类型的定义。

在 Java 中，Button 是一个类，用于创建图形界面中的按钮控件。如果你想在代码中使用 Button 类型，需要在代码中导入 java.awt 包或 javax.swing 包。

例如，如果你正在使用 javax.swing 包，可以在代码开头添加以下导入语句：

import javax.swing.JButton;

这样就可以在代码中使用 JButton 类型来创建按钮控件了。请注意，不同的包中可能还有其他类名相同的类型，因此需要根据实际情况选择正确的包和类。