Java Android MediaRecorder NullPointerException
我刚开始Java开发,现在正在摆弄Android媒体录制器。但是,我得到一个NullPointerException,我使用以下源代码单击record按钮:Java Android MediaRecorder NullPointerException,java,android,Java,Android,我刚开始Java开发,现在正在摆弄Android媒体录制器。但是,我得到一个NullPointerException,我使用以下源代码单击record按钮: import android.support.v7.app.ActionBarActivity; import android.os.Bundle; //import android.net.Uri; import android.view.Menu; import android.view.MenuItem; import android
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
//import android.net.Uri;
import android.view.Menu;
import android.view.MenuItem;
import android.os.Environment;
import android.view.View;
import java.io.File;
import java.io.IOException;
import android.media.MediaPlayer;
import android.media.MediaRecorder;
import java.lang.String;
public class MainActivity extends ActionBarActivity {
String outputFile = "test.3gp";
private MediaRecorder myAudioRecorder;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
MediaRecorder myAudioRecorder = new MediaRecorder();
myAudioRecorder = new MediaRecorder();
// Uri target = Uri.parse(outputFile.getAbsolutePath());
myAudioRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
myAudioRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
myAudioRecorder.setAudioEncoder(MediaRecorder.OutputFormat.AMR_NB);
myAudioRecorder.setOutputFile(outputFile);
}
public void Start_Record(View v)
{
try {
myAudioRecorder.prepare();
myAudioRecorder.start();
} catch (IllegalStateException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
myAudioRecorder.stop();
myAudioRecorder.release();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
我意识到这可能是因为fill指针被设置为NULL,但是我很难看到如何初始化文件引用以使其消失。我在mediaRecorderPrepare()上遇到了一个异常
以下是引发的异常:
03-09 22:53:56.548 31836-31836/uk.co.spectralgear.spectralboost E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.IllegalStateException: Could not execute method of the activity
at android.view.View$1.onClick(View.java:4007)
at android.view.View.performClick(View.java:4756)
at android.view.View$PerformClick.run(View.java:19749)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at android.view.View$1.onClick(View.java:4002)
at android.view.View.performClick(View.java:4756)
at android.view.View$PerformClick.run(View.java:19749)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.media.MediaRecorder.prepare()' on a null object reference
at uk.co..MainActivity.Start_Record(MainActivity.java:38)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at android.view.View$1.onClick(View.java:4002)
at android.view.View.performClick(View.java:4756)
at android.view.View$PerformClick.run(View.java:19749)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
任何帮助都将不胜感激:)问题:
当“Start_Record()”尝试使用类变量“myAudioRecord”时,该类变量为null:
Caused by: java.lang.NullPointerException:
Attempt to invoke virtual method 'void Android.media.MediaRecorder.prepare()' on a null object reference
解决方案:从“onCreate()”方法中删除此行:
onCreate()内部的“myAudioRecorder”声明隐藏了外部声明。所以外部(类级别)“myAudioRecorder”永远不会初始化。。。当“Start_Record()”试图访问程序时,程序将因NPE而死亡
附言:
请考虑将方法名更改为“StasyRealDebug()”。或者更好,“startRecord()。这与Java命名约定更加一致。
我认为您正在使用已停止的stop()
函数。检查您的代码和逻辑。可能存在重复的
public class MainActivity extends ActionBarActivity {
String outputFile = "test.3gp";
private MediaRecorder myAudioRecorder; // Your class variable: OK...
@Override
protected void onCreate(Bundle savedInstanceState) {
...
// MediaRecorder myAudioRecorder = new MediaRecorder(); // DELETE THIS LINE!!!
myAudioRecorder = new MediaRecorder(); // OK...
...