调用从活动

Question

我打电话从我的活动的布局外视图的布局之外，所以我做的一个观点：

View v = inflater.inflate(R.layout.image_view_layout, null); 
ImageView iv = (ImageView) v.findViewById(R.id.img_pager); 

其中R.layout.image_view_layout是视图的布局打电话，R.id.img_pager是我想调用的视图，但为什么会出现空指针异常？

这是我的image_view_layout.xml文件：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:orientation="vertical" 
    > 

    <ImageView 
     android:id="@+id/img_pager" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:contentDescription="@string/desc_intro" 
     android:scaleType="fitXY" 
     android:adjustViewBounds="true" 


     /> 

</LinearLayout> 

那是logcat的：

01-14 07:33:19.204: E/AndroidRuntime(22767): FATAL EXCEPTION: main 
01-14 07:33:19.204: E/AndroidRuntime(22767): java.lang.RuntimeException: Unable to start activity ComponentInfo{package_name/packagename.Introduction_Activity}: java.lang.NullPointerException 
01-14 07:33:19.204: E/AndroidRuntime(22767): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2100) 
01-14 07:33:19.204: E/AndroidRuntime(22767): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2125) 
01-14 07:33:19.204: E/AndroidRuntime(22767): at android.app.ActivityThread.access$600(ActivityThread.java:140) 
01-14 07:33:19.204: E/AndroidRuntime(22767): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1227) 
01-14 07:33:19.204: E/AndroidRuntime(22767): at android.os.Handler.dispatchMessage(Handler.java:99) 
01-14 07:33:19.204: E/AndroidRuntime(22767): at android.os.Looper.loop(Looper.java:137) 
01-14 07:33:19.204: E/AndroidRuntime(22767): at android.app.ActivityThread.main(ActivityThread.java:4898) 
01-14 07:33:19.204: E/AndroidRuntime(22767): at java.lang.reflect.Method.invokeNative(Native Method) 
01-14 07:33:19.204: E/AndroidRuntime(22767): at java.lang.reflect.Method.invoke(Method.java:511) 
01-14 07:33:19.204: E/AndroidRuntime(22767): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1006) 
01-14 07:33:19.204: E/AndroidRuntime(22767): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:773) 
01-14 07:33:19.204: E/AndroidRuntime(22767): at dalvik.system.NativeStart.main(Native Method) 
01-14 07:33:19.204: E/AndroidRuntime(22767): Caused by: java.lang.NullPointerException 
01-14 07:33:19.204: E/AndroidRuntime(22767): at packagename.Introduction_Activity.onCreate(Introduction_Activity.java:45) 
01-14 07:33:19.204: E/AndroidRuntime(22767): at android.app.Activity.performCreate(Activity.java:5206) 
01-14 07:33:19.204: E/AndroidRuntime(22767): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1083) 
01-14 07:33:19.204: E/AndroidRuntime(22767): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2064) 
01-14 07:33:19.204: E/AndroidRuntime(22767): ... 11 more 

这就是onCreate方法：

protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_introduction); 
     View v = inflater.inflate(R.layout.image_view_layout, null); 
     iv = (ImageView) v.findViewById(R.id.img_pager); 


     zc = (ZoomControls) findViewById(R.id.zoomControls1); 
     zc.setOnZoomInClickListener(new OnClickListener() { 
      public void onClick(View v) { 
       float oldZoom = currentZoom; 
       currentZoom = (float) (currentZoom * 1.25); 
       zc.setIsZoomOutEnabled(true); 
       if (3.0 < currentZoom) { 
        zc.setIsZoomInEnabled(false); 
       } 
       scaleAnim = new ScaleAnimation(oldZoom, currentZoom, oldZoom, currentZoom, 0, 0); 
       scaleAnim.setFillAfter(true); 
       iv.startAnimation(scaleAnim); 
      } 
     }); 
     zc.setOnZoomOutClickListener(new OnClickListener() { 
      public void onClick(View v) { 
       float oldZoom = currentZoom; 
       currentZoom = (float) (currentZoom/1.25); 
       zc.setIsZoomInEnabled(true); 
       if (0.33 > currentZoom) { 
        zc.setIsZoomOutEnabled(false); 
       } 
       scaleAnim = new ScaleAnimation(oldZoom, currentZoom, oldZoom, currentZoom, 0, 0); 
       scaleAnim.setFillAfter(true); 
       iv.startAnimation(scaleAnim); 
      } 
     }); 

     // Instantiate a ViewPager and a PagerAdapter. 
     mPager = (ViewPager) findViewById(R.id.imgs_viewpager); 
     mPagerAdapter = new ScreenSlidePagerAdapter(getSupportFragmentManager()); 
     mPager.setAdapter(mPagerAdapter); 
     mPager.setCurrentItem(NUM_PAGES-1,false);  
    } 

Answer 1

做到像这样

LayoutInflater layoutInflater = = (LayoutInflater) yourclasscontext.getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
View view = layoutInflater.inflate(R.layout.image_view_layout, this); 
ImageView iv = (ImageView) view .findViewById(R.id.img_pager); 

你可以按照这个链接Inflating and Encapsulating Layout XML into View Object in Android

Answer 2

试试这个，

LinearLayout mAddOnForSaladLnrLyt = (LinearLayout) findViewById(R.id.your_layout_id); 

LayoutInflater inflater = this.getLayoutInflater(); 

View v = inflater.inflate(R.layout.image_view_layout, null); 
ImageView iv = (ImageView) view .findViewById(R.id.img_pager); 
mAddOnForSaladLnrLyt.addView(v);