Question

我正在尝试将音乐添加到我的程序中，以使其听起来像商业广告，所以说，就像一家名为PizzaPalooza的披萨公司而言，我会收到一些错误，例如

error: method addActionListener in class AbstractButton cannot be applied to given types

JPizza.java:77: error: incompatible types if(source = playButton) ^ required: boolean found: Object

JPizza.java:69: error: method addActionListener in class AbstractButton cannot be applied to given types; playButton.addActionListener(this); ^ required: ActionListener found: JPizza

仅举几个例子，为此我尝试创建source

的新对象

但我不明白method addActionListener in class AbstractButton cannot be applied to given types

的含义

对于这些，我必须重做整个事情并extend ActionListener吗？或者我可以用另一种方式吗？我很难理解JApplets。

提前致谢！

这是抛出问题的代码的一部分：

public void init()
{
  Container Con = getContentPane();
  con.setLayout (new FlowLayout());
  con.add(listenLabel);
  con.add(playButton);
  con.add(stopButton);
  playButton.addActionListener(this);
  stopButton.addActionListener(this);
  music = getAudioClip(getCodeBase(),"business.mid");
}

public void actionPerformed(ActionEvent e)
{
  Object source = e.getSource();
  if(source = playButton)
     music.loop();
  else
     music.stop();
}

这是我的其余代码：

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

public class JPizza extends JFrame implements ItemListener
{
   FlowLayout flow = new FlowLayout();
   JLabel companyName = new JLabel("PizzaPalooza");
   JComboBox<String> sizeBox = new JComboBox<String>();
   JLabel sizeList = new JLabel("Size List");
   JComboBox<String> toppingBox = new JComboBox<String>();
   JLabel toppingList = new JLabel("Topping List");
   JTextField totPrice = new JTextField(10);
   JLabel orderName = new JLabel("Name of Order");
   JTextField oName = new JTextField(15);
   JLabel listenLabel = new JLabel("Listen to our theme!");
   JButton playButton = new JButton("Play");
   JButton stopButton = new JButton("Stop");
   AudioClip music;
   int totalPrice = 0;
   int sizeNum, toppingNum;
   int sPrice, tPrice, sumPrice;
   int[] sizePrice = {0,7,9,11,14};
   int[] toppingPrice = {0,0,1,1,1,1};
   String output;
   public JPizza()
   {
     super("PizzaPalooza");
     setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);   
     setLayout(flow);
     add(companyName);
     companyName.setFont(new Font("Ariel", Font.BOLD, 20));
     sizeBox.addItem("None");
     sizeBox.addItem("Small");
     sizeBox.addItem("Medium");
     sizeBox.addItem("Large");
     sizeBox.addItem("Extra large");
     toppingBox.addItem("None");
     toppingBox.addItem("Cheese");
     toppingBox.addItem("Sausage");
     toppingBox.addItem("Pepperoni");
     toppingBox.addItem("Green pepper");
     toppingBox.addItem("Onion");
     add(sizeList);
     add(sizeBox);
      sizeBox.addItemListener(this);
     add(toppingList);
  add(toppingBox);
      toppingBox.addItemListener(this);
     add(totPrice);
     add(oName);
     add(orderName);
  }
   public static void main(String[] arguments)
    {
      JPizza pframe = new JPizza();
      pframe.setSize(380,200);
      pframe.setVisible(true);
    }

   public void init()
    {
      Container Con = getContentPane();
      con.setLayout (new FlowLayout());
      con.add(listenLabel);
      con.add(playButton);
      con.add(stopButton);
      playButton.addActionListener(this);
      stopButton.addActionListener(this);
      music = getAudioClip(getCodeBase(),"business.mid");
    }

    public void actionPerformed(ActionEvent e)
    {
      Object source = e.getSource();
      if(source = playButton)
        music.loop();
      else
        music.stop();
    }

  public void itemStateChanged(ItemEvent list)
    {
      Object source = list.getSource();
      if (source == sizeBox)
      {
        sizeNum = sizeBox.getSelectedIndex();
        sPrice = sizePrice[sizeNum];
        sumPrice = sPrice + tPrice;
        output = "Total Price $" + sumPrice;
        totPrice.setText(output);
      }
      else if (source == toppingBox)
       {
         toppingNum = toppingBox.getSelectedIndex();
         tPrice = toppingPrice[toppingNum];
         sumPrice = sPrice + tPrice;
         output = "Total Price $" + sumPrice;
         totPrice.setText(output);
      }
   }
}

Answer 1

第一个错误

if(source = playButton)

是赋值，而不是布尔比较器。它产生赋值的结果，在本例中是Button对象。相反，你需要写：

if(source == playButton)

注意双等号。

第二次错误

JPizza不是ActionListener - 如果要将其用作一个接口，则需要让它扩展此接口：

public class JPizza extends JFrame implements ActionListener

错误：类AbstractButton中的方法addActionListener无法应用于给定类型

1 个答案: