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Making a Swing application in which a user selects an audio file using a radio button and plays it using the Play button. The GUI class call the method from a custom audio handler class. The audio files are in a package called audio. The following errors are thrown after sound selection and the user clicks the Play button:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at sun.audio.AudioStream.<init>(AudioStream.java:63)
at my.quotesbutton.Player.fear(Player.java:18)
at my.quotesbutton.QuotesButtonUI.jButton3ActionPerformed(QuotesButtonUI.java:221)
at my.quotesbutton.QuotesButtonUI.access$000(QuotesButtonUI.java:16)
at my.quotesbutton.QuotesButtonUI$1.actionPerformed(QuotesButtonUI.java:66)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
at java.awt.Component.processMouseEvent(Component.java:6505)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
at java.awt.Component.processEvent(Component.java:6270)
at java.awt.Container.processEvent(Container.java:2229)
at java.awt.Component.dispatchEventImpl(Component.java:4861)
at java.awt.Container.dispatchEventImpl(Container.java:2287)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
at java.awt.Container.dispatchEventImpl(Container.java:2273)
at java.awt.Window.dispatchEventImpl(Window.java:2719)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:735)
at java.awt.EventQueue.access$200(EventQueue.java:103)
at java.awt.EventQueue$3.run(EventQueue.java:694)
at java.awt.EventQueue$3.run(EventQueue.java:692)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
at java.awt.EventQueue$4.run(EventQueue.java:708)
at java.awt.EventQueue$4.run(EventQueue.java:706)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:705)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)

The GUI class code as follows:

private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        if (jRadioButton1.isSelected()){

                Player play = new Player();
            try {
                play.fear();
            } catch (IOException ex) {
                Logger.getLogger(QuotesButtonUI.class.getName()).log(Level.SEVERE, null, ex);
            }
        }
        else if (jRadioButton2.isSelected()){

        }
        else if (jRadioButton3.isSelected()){

        }
        else if (jRadioButton4.isSelected()){

        }
        else if (jRadioButton5.isSelected()){

        }
        else if (jRadioButton6.isSelected()){

        } 
        else {

        }

    }                                        

    private void jButton4ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        System.exit(0);
    }                                        

The code for the audio handler class as follows:

    package my.quotesbutton;

import java.io.*;
import sun.audio.AudioPlayer;
import sun.audio.AudioStream;

public class Player{

  public void fear() throws IOException{


    InputStream inputStream = getClass().getResourceAsStream("audio\\fear.wav");
    AudioStream audioStream = new AudioStream(inputStream);
    AudioPlayer.player.start(audioStream);

    }
}
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1 回答 1

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好像您正在传递nullAudioStream构造函数。您传递给它的值是通过getClass().getResourceAsStream().

来自 Java Classjavadoc:

public InputStream getResourceAsStream(String name)

...

返回:
一个InputStream对象,或者null如果没有找到同名的资源

所以,这可能返回的方式null是找不到文件。问题出在您的文件路径中。您经过的路径是相对的。尝试查找应用程序的工作目录在哪里,并更正相对于它的路径。

编辑:您可以通过System.getProperty("user.dir").

于 2013-11-12T18:02:48.600 回答