Question

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

/**
 * This programs counts the cars entering and leaving a car park, always displaying
 * the current number of cars in the car park.
 */
public class CarPark extends JFrame
implements ActionListener{

/**
 * Globally accessible counter for the number of cars in the car park
 */
private int carCount = 0;

/**
 * Globally accessible counter for the number of mini buses in the car park
 */
private int miniCount = 0;

/**
 * Globally accessible counter for the total amount of spaces left
 */
private int limitCalc = 100;

/**
 * Buttons to simulate cars entering and leaving the car park.
 */
private JButton enter, exit, miniEnter, miniExit;

/**
 * Text field where the current number of cars is displayed
 */
private JTextField text, miniText, carMax;

/**
 * The main launch method
 */

public static void main(String[] args)
{
    CarPark frame = new CarPark();
    frame.setSize(400, 250);
    frame.setLocation(150, 150);
    frame.setTitle("Car Park");
    frame.createGUI();
    frame.setVisible(true);

}

/**
 * React to a GUI button press by adjusting the car counter correctly,
 * and then updating the counter display
 */
/**
 * Helper method to build up the GUI
 */
private void createGUI()
{
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    Container window = getContentPane();
    window.setLayout(new FlowLayout());

    int carLimit = 100;

    enter = new JButton("Car Entering");
    window.add(enter);
    enter.addActionListener(this);

    text = new JTextField("0   ");
    text.setFont(new Font("Arial", Font.BOLD, 40));
    window.add(text);

    exit = new JButton("Car Exiting");
    window.add(exit);
    exit.addActionListener(this);

    miniEnter = new JButton("Minibus Entering");
    window.add(miniEnter);
    miniEnter.addActionListener(this);

    miniText = new JTextField("0   ");
    miniText.setFont(new Font("Arial", Font.BOLD, 40));
    window.add(miniText);

    miniExit = new JButton("Minibus Exiting");
    window.add(miniExit);
    miniExit.addActionListener(this);

    carMax = new JTextField(carLimit + "");
    carMax.setFont(new Font("Arial", Font.BOLD, 40));
    window.add(carMax);
}

public void actionPerformed(ActionEvent event, int carLimit)
{
    if (event.getSource() == enter)
    {
        carCount = carCount + 1;
        limitCalc = limitCalc-1;
        System.out.println(limitCalc);
    }
    if (event.getSource() == exit)
    {
        carCount = carCount-1;
        limitCalc = limitCalc +1;
        System.out.println(limitCalc);
    }
    if (event.getSource() == miniEnter)
    {
        miniCount = miniCount+1;
        limitCalc = limitCalc -1;
        System.out.println(limitCalc);
    }
    if (event.getSource() == miniExit)
    {
        miniCount = miniCount-1;
        limitCalc = limitCalc +1;
        System.out.println(limitCalc);
    }

    miniText.setText(Integer.toString(miniCount));
    text.setText(Integer.toString(carCount));

}

private int carCalculations(int carLimit)
{
    int carTotal = carCount + miniCount;
    limitCalc = limitCalc - carTotal;
    carLimit = limitCalc;
    System.out.println(carLimit);
    return carLimit;
}
}

我一直收到此错误

"CarPark is not abstract and does not override abstract method actionPerformed(java.awt.event.ActionEvent) in java.awt.event.ActionListener

我做错了什么？提前致谢

Answer 1

而不是覆盖actionPerformed(ActionEvent)方法，而是使用actionPerformed(ActionEvent, int)重载它。

考虑一下如何从方法签名中删除int部分。

CarPark不是抽象的，不会覆盖抽象方法（需要帮助）

1 个答案: