java - android 录制停止时出现 NullPointerException

Question

我正在尝试制作一个应用程序，该应用程序在单击按钮时开始录制，再次单击按钮时停止录制。我认为录制时没有问题，但是当我再次单击按钮时，应用程序因 NullPointerException 崩溃，据说在无效状态下调用了 stop 1

我的代码:

package com.example.victwo;

import java.io.IOException;

import android.media.MediaRecorder;

public class Audio {
    private String path;

    MediaRecorder myAudioRecorder = null;

    public Audio(String path) {
        this.path = path;
    }

    public void play() {

    }

    public void startRecording() {
        myAudioRecorder = new MediaRecorder();
        myAudioRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
        myAudioRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
        myAudioRecorder.setAudioEncoder(MediaRecorder.OutputFormat.AMR_NB);
        myAudioRecorder.setOutputFile(path);

        try {
            myAudioRecorder.prepare();
        } catch (IllegalStateException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        myAudioRecorder.start();
    }

    public void stopRecording() {
        myAudioRecorder.stop();
        myAudioRecorder.release();
        myAudioRecorder = null;
    }

}

这是我调用音频类方法的 Activity 的代码:

    case R.id.action_record:
        Audio recAndPlay = new Audio(this.path + "/" + this.title);

        if(flag == 0) {
            Log.d("RECORD", "START");
            flag = 1;
            if(title.equals("")) {
                setTitle();
            }
            recAndPlay.startRecording();
            return true;
        }

        if(flag == 1) {
            Log.d("RECORD", "STOP");
            recAndPlay.stopRecording();
        }
        return true;

日志猫:

04-05 14:02:58.909: E/AndroidRuntime(5730): FATAL EXCEPTION: main
04-05 14:02:58.909: E/AndroidRuntime(5730): java.lang.NullPointerException
04-05 14:02:58.909: E/AndroidRuntime(5730):     at com.example.victwo.Audio.stopRecording(Audio.java:41)
04-05 14:02:58.909: E/AndroidRuntime(5730):     at com.example.victwo.NoteActivity.onOptionsItemSelected(NoteActivity.java:158)
04-05 14:02:58.909: E/AndroidRuntime(5730):     at android.app.Activity.onMenuItemSelected(Activity.java:2205)
04-05 14:02:58.909: E/AndroidRuntime(5730):     at android.support.v4.app.FragmentActivity.onMenuItemSelected(FragmentActivity.java:372)
04-05 14:02:58.909: E/AndroidRuntime(5730):     at android.support.v7.app.ActionBarActivity.superOnMenuItemSelected(ActionBarActivity.java:244)
04-05 14:02:58.909: E/AndroidRuntime(5730):     at android.support.v7.app.ActionBarActivityDelegateBase.onMenuItemSelected(ActionBarActivityDelegateBase.java:339)
04-05 14:02:58.909: E/AndroidRuntime(5730):     at android.support.v7.app.ActionBarActivity.onMenuItemSelected(ActionBarActivity.java:130)
04-05 14:02:58.909: E/AndroidRuntime(5730):     at android.support.v7.app.ActionBarActivityDelegateBase.onMenuItemSelected(ActionBarActivityDelegateBase.java:344)
04-05 14:02:58.909: E/AndroidRuntime(5730):     at android.support.v7.internal.view.menu.MenuBuilder.dispatchMenuItemSelected(MenuBuilder.java:777)
04-05 14:02:58.909: E/AndroidRuntime(5730):     at android.support.v7.internal.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:158)
04-05 14:02:58.909: E/AndroidRuntime(5730):     at android.support.v7.internal.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:922)
04-05 14:02:58.909: E/AndroidRuntime(5730):     at android.support.v7.internal.view.menu.ActionMenuView.invokeItem(ActionMenuView.java:544)
04-05 14:02:58.909: E/AndroidRuntime(5730):     at android.support.v7.internal.view.menu.ActionMenuItemView.onClick(ActionMenuItemView.java:105)
04-05 14:02:58.909: E/AndroidRuntime(5730):     at android.view.View.performClick(View.java:2485)
04-05 14:02:58.909: E/AndroidRuntime(5730):     at android.view.View$PerformClick.run(View.java:9080)
04-05 14:02:58.909: E/AndroidRuntime(5730):     at android.os.Handler.handleCallback(Handler.java:587)
04-05 14:02:58.909: E/AndroidRuntime(5730):     at android.os.Handler.dispatchMessage(Handler.java:92)
04-05 14:02:58.909: E/AndroidRuntime(5730):     at android.os.Looper.loop(Looper.java:123)
04-05 14:02:58.909: E/AndroidRuntime(5730):     at android.app.ActivityThread.main(ActivityThread.java:3683)
04-05 14:02:58.909: E/AndroidRuntime(5730):     at java.lang.reflect.Method.invokeNative(Native Method)
04-05 14:02:58.909: E/AndroidRuntime(5730):     at java.lang.reflect.Method.invoke(Method.java:507)
04-05 14:02:58.909: E/AndroidRuntime(5730):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
04-05 14:02:58.909: E/AndroidRuntime(5730):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
04-05 14:02:58.909: E/AndroidRuntime(5730):     at dalvik.system.NativeStart.main(Native Method)

Answer 1

在 startRecording() 之外初始化您的媒体播放器

 myAudioRecorder = new MediaRecorder();

修改您的代码，如下所示

public class Audio {
private String path;




MediaRecorder myAudioRecorder = new MediaRecorder();

public Audio(String path) {
    this.path = path;
}

public void play() {

}

public void startRecording() {

    myAudioRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
    myAudioRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
    myAudioRecorder.setAudioEncoder(MediaRecorder.OutputFormat.AMR_NB);
    myAudioRecorder.setOutputFile(path);

    try {
        myAudioRecorder.prepare();
    } catch (IllegalStateException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    myAudioRecorder.start();
}

public void stopRecording() {
    myAudioRecorder.stop();
    myAudioRecorder.release();
    myAudioRecorder = null;
}
}

希望这对您有帮助