为视频视图提供视频路径时出现空指针异常错误

Question

我在为我的视频视图提供视频路径时收到NullPointerException错误，导致我的应用程序在开始时崩溃。 我已经使用了setVideoURI()和setVideoPath()方法，但我仍然面临这个问题！ 这是我的代码：

主要活动.java ：

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.VideoView;

public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
VideoView videoView = (VideoView) findViewById(R.id.video);
videoView.setVideoPath("android.resource://" + getPackageName() + "/" + R.raw.video);
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
}

activity_main.xml ：

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 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:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<VideoView
android:id="@+id/video"
android:layout_width="566dp"
android:layout_height="230dp"
tools:layout_editor_absoluteX="0dp"
tools:layout_editor_absoluteY="0dp" />
</android.support.constraint.ConstraintLayout>

日志猫 ：

06-09 01:31:02.898 15912-15912/com.example.avail.video E/dalvikvm: Could not find class 'android.graphics.drawable.RippleDrawable', referenced from method android.support.v7.widget.AppCompatImageHelper.hasOverlappingRendering
06-09 01:31:02.948 15912-15912/com.example.avail.video E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.avail.video, PID: 15912
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.avail.video/com.example.avail.video.MainActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2198)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2257)
at android.app.ActivityThread.access$800(ActivityThread.java:139)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1210)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5097)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.example.avail.video.MainActivity.onCreate(MainActivity.java:14)
at android.app.Activity.performCreate(Activity.java:5248)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1110)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2162)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2257) 
at android.app.ActivityThread.access$800(ActivityThread.java:139) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1210) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:136) 
at android.app.ActivityThread.main(ActivityThread.java:5097) 
at java.lang.reflect.Method.invokeNative(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:515) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601) 
at dalvik.system.NativeStart.main(Native Method) 

任何帮助将不胜感激！

Answer 1

调用方法的顺序不正确。它应该是这样的：

protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
VideoView videoView = (VideoView) findViewById(R.id.video);
videoView.setVideoPath("android.resource://" + getPackageName() + "/" + R.raw.video);
}