Android 下面的错误是什么意思？

这些是日志-

  @Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

   // overridePendingTransition(R.anim.fadein, R.anim.fadeout);
    setContentView(R.layout.activity_intro);

    ImageView image = (ImageView) findViewById(R.id.myImageView);
    image.setImageResource(R.drawable.landscape);

    // go to the intro activity when button is pressed
    Button introBtn = (Button) findViewById(R.id.introBtn);
    introBtn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View arg0) {
            startActivity(new Intent(MainActivity.this, IntroActivity.class));
        }});

    // when back btn is pressed the previous image shows up
    Button backBtn = (Button) findViewById(R.id.previousBtn);
    backBtn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View arg0) {
              backImage();
            ImageView image1 = (ImageView) findViewById(R.id.myImageView);
            image1.setImageResource(allDrawableImages.get(count));
        }

    });

    // a btn to set wallpaper
    Button setWallBtn = (Button)findViewById(R.id.setWallpaper);
    setWallBtn.setOnClickListener(new Button.OnClickListener(){
        @Override
        public void onClick(View arg0) {
            // TODO Auto-generated method stub
            WallpaperManager myWallpaperManager
                    = WallpaperManager.getInstance(getApplicationContext());
            try {
                myWallpaperManager.setResource(allRawImages.get(count));
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }});

    // go to the next wallpaper image
    Button nextBtn = (Button) findViewById(R.id.nextBtn);
    nextBtn.setOnClickListener(new Button.OnClickListener(){

        @Override
        public void onClick(View arg0){
               nextImage();
            ImageView image2 = (ImageView) findViewById(R.id.myImageView);
            image2.setImageResource(allDrawableImages.get(count));
            }
        });
        }

“原因：java.lang.NullPointerException:尝试在空对象引用上调用虚拟方法”“void android.widget.ImageView.setImageResource（int）”

---

您试图设置一些不存在的内容。如果确实存在，请仔细检查所有括号的位置。如果哪怕是稍微有点混乱，它也不会正常工作。

在某个地方设置一个断点，并检查

（ImageView）findViewById（R.id.myImageView）为您提供了有效的ImageView。它也可能在您的循环中，
image2.setImageResource（allDrawableImages.get（count））
。
   03-13 01:14:06.310 7780-7780/com.wube.wubewallpaper
 E/AndroidRuntime: FATAL EXCEPTION: main


Process: com.wube.wubewallpaper, PID: 7780
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.wube.wubewallpaper/com.wube.wubewallpaper.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ImageView.setImageResource(int)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2646)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ImageView.setImageResource(int)' on a null object reference
at com.wube.wubewallpaper.MainActivity.onCreate(MainActivity.java:39)
at android.app.Activity.performCreate(Activity.java:6662)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2599)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707) 
at android.app.ActivityThread.-wrap12(ActivityThread.java) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:154) 
at android.app.ActivityThread.main(ActivityThread.java:6077) 
at java.lang.reflect.Method.invoke(Native Method)