这是MediaPlayer1.class
import android.media.MediaPlayer;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
public class MediaPlayer1 extends AppCompatActivity {
MediaPlayer mpAudio;
Boolean play;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_media_player);
play = false;
mpAudio = MediaPlayer.create(this, R.raw.youngagain);
mpAudio.setLooping(true);
Button bPlay = (Button) findViewById(R.id.playBtn);
bPlay.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (play == false)
mpAudio.start();
else
mpAudio.pause();
play = !play;
}
});
}
}
和布局文件activity_media_player.xml
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/base_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@color/background_material_dark"
android:gravity="center_horizontal"
android:orientation="vertical"
tools:context=".MainActivity">
<ImageView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:src="@drawable/zmountain"
android:scaleType="centerCrop"
android:foreground="#e1000000" />
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:layout_marginLeft="20dp"
android:layout_marginRight="20dp">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Hardwell on Air"
android:textColor="#fafafa"
android:textSize="24sp"
android:textStyle="bold"
android:layout_marginTop="60dp"
android:layout_marginBottom="10dp" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceMedium"
android:text="Hardwell on Air"
android:textColor="#fafafa"
android:layout_marginBottom="20dp"
android:id="@+id/textView" />
<sas.unplug.SquareImageView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scaleType="centerCrop"
android:src="@drawable/zghost" />
<com.wnafee.vector.MorphButton
android:id="@+id/playBtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_margin="5dp"
android:background="@null"
app:vc_endDrawable="@drawable/ic_pause_to_play"
app:vc_foregroundTint="@color/colorAccent"
app:vc_startDrawable="@drawable/ic_play_to_pause" />
</LinearLayout>
</FrameLayout>
我的活动上面出现以下错误，我通过我的适配器调用了这个错误，如下所示：
@Override
public void onBindViewHolder(final ViewHolder holder, final int position) {
final PodcastData item = items.get(position);
holder.ptitle.setText(item.getPTitle());
holder.plikes.setText(""+item.getPLikes());
//Converting image into a bitmap
Bitmap bitmap = item.getAlbum();
//usig the generate method
Palette palette = Palette.generate(bitmap, 16);
Palette.generateAsync(bitmap, 16, new Palette.PaletteAsyncListener() {
@Override
public void onGenerated(Palette palette) {
Palette.Swatch vibrant = palette.getVibrantSwatch();
if (vibrant != null) {
// If we have a vibrant color
// update the title TextView
holder.ptitle.setTextColor(vibrant.getTitleTextColor());
holder.ptitle.setBackgroundColor(vibrant.getRgb());
}
}
});
holder.album.setImageBitmap(item.getAlbum());
holder.bLike.setOnClickListener(new View.OnClickListener() {
int likes = item.getPLikes();
@Override
public void onClick(View v) {
Toast.makeText(v.getContext(), "Likes selected " + items.get(position).getPLikes(), Toast.LENGTH_SHORT).show();
if(item.liked) {
holder.bLike.setColorFilter(Color.argb(255, 255, 255, 255));
likes-=1;
}
else {
holder.bLike.setColorFilter(Color.argb(255, 255, 38, 38));
likes+=1;
}
item.liked = !item.liked;
items.get(position).setPlikes(likes);
item.setPlikes(likes);
holder.plikes.setText("" + item.getPLikes());
ParseQuery<ParseObject> query = ParseQuery.getQuery("Podcast");
query.whereEqualTo("name", item.getPTitle());
query.getInBackground(item.objectId, new GetCallback<ParseObject>() {
@Override
public void done(ParseObject object, ParseException e) {
if (e == null) {
object.put("likes", likes);
object.saveInBackground();
}
}
});
}
});
holder.album.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(context, MediaPlayer1.class); // Start MediaPlayer1 activity here
context.startActivity(intent);
}
});
}
FATAL EXCEPTION: main
Process: sas.unplug, PID: 1715
java.lang.RuntimeException: Unable to start activity ComponentInfo{sas.unplug/sas.unplug.MediaPlayer1}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.media.MediaPlayer.setLooping(boolean)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.media.MediaPlayer.setLooping(boolean)' on a null object reference
at sas.unplug.MediaPlayer1.onCreate(MediaPlayer1.java:21)
at android.app.Activity.performCreate(Activity.java:6237)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
我正在单独运行与单独项目完全相同的代码，并且播放器在那里工作正常但是只要我在我的主项目中启动此活动，我的应用就崩溃了。请帮助我，因为我明天提交了我的小项目，所以我非常需要帮助。
答案 0 :(得分：0)
mpAudio = MediaPlayer.create(this, R.raw.youngagain)
MediaPlayer.create()返回MediaPlayer个对象，如果创建失败，则返回null。
MediaPlayer.create() failed and mpAudio = null .
所以当你mpAudio.setLoop时，你会得到nullpointer错误。