#（Unable to start activity ComponentInfo{XXX}: java.lang.NullPointerException）#

wzysys1617 2014-07-22 05:50:10
新人求助！！！在调试的时候，Exception显示的错误是：

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.andyidea.tabdemo/com.andyidea.tabdemo.Item_java}: java.lang.NullPointerException



怎么解决啊？求助啊！！有没有人帮我啊！！谢谢各位了！！！

代码如下：

public class BActivity extends ActivityGroup{

	

	private ViewPager viewPager;//页卡内容

	private ImageView imageView;// 动画图片

	private Button button3,button4,button5,button6;

	private List<View> views;// Tab页面列表

	private int offset = 0;// 动画图片偏移量

	private int currIndex = 0;// 当前页卡编号

	private int bmpW;// 动画图片宽度

	private View view1,view2,view3,view4;//各个页卡

	@Override

	protected void onCreate(Bundle savedInstanceState) {

		super.onCreate(savedInstanceState);

		setContentView(R.layout.bmain);

		InitImageView();

		InitButtonView();

		InitViewPager();

	}

	

	private void InitViewPager() {

		viewPager=(ViewPager) findViewById(R.id.Bviewpager);

		try{

		 view1 = getLocalActivityManager().startActivity("MainActivity",

                  new Intent(this, Item_java.class)).getDecorView();     //这个地方，try的时候无法通过。就在这里跳到catch了。

         view2 = getLocalActivityManager().startActivity("MainActivity",

                  new Intent(this, Item_dotnet.class)).getDecorView();

         view3 = getLocalActivityManager().startActivity("MainActivity",

                  new Intent(this, Item_insertapp.class)).getDecorView();

         view4 = getLocalActivityManager().startActivity("MainActivity",

                 new Intent(this, Item_netmanagement.class)).getDecorView();

		views=new ArrayList<View>();

		views.add(view1);

		views.add(view2);

		views.add(view3);

		views.add(view4);

		viewPager.setAdapter(new MyViewPagerAdapter(views));

		viewPager.setCurrentItem(0);

		viewPager.setOnPageChangeListener(new MyOnPageChangeListener());

		}

		catch (Exception e) {

			// TODO: handle exception

			int xx=1;

		}



	}

	 /**

	  *  初始化头标

	  */



	private void InitButtonView() {

		button3 = (Button) findViewById(R.id.btn_java);

		button4 = (Button) findViewById(R.id.btn_dotnet);

		button5 = (Button) findViewById(R.id.btn_insertapp);

		button6 = (Button) findViewById(R.id.btn_netmanagement);

		button3.setOnClickListener(new MyOnClickListener(0));

		button4.setOnClickListener(new MyOnClickListener(1));

		button5.setOnClickListener(new MyOnClickListener(2));

		button6.setOnClickListener(new MyOnClickListener(3));

	}



	/**

	 2      * 初始化动画，这个就是页卡滑动时，下面的横线也滑动的效果，在这里需要计算一些数据

	 3 */



	private void InitImageView() {

		imageView= (ImageView) findViewById(R.id.Bcursor);

		bmpW = BitmapFactory.decodeResource(getResources(), R.drawable.a).getWidth();// 获取图片宽度

		DisplayMetrics dm = new DisplayMetrics();

		getWindowManager().getDefaultDisplay().getMetrics(dm);

		int screenW = dm.widthPixels;// 获取分辨率宽度

		offset = (screenW /4 - bmpW) / 2;// 计算偏移量

		Matrix matrix = new Matrix();

		matrix.postTranslate(offset, 0);

		imageView.setImageMatrix(matrix);// 设置动画初始位置

	}	

	/** 

	 *     

	 * 头标点击监听 3 */

	 private class MyOnClickListener implements OnClickListener{

        private int index=0;

        public MyOnClickListener(int i){

        	index=i;

        }

		public void onClick(View v) {

			viewPager.setCurrentItem(index);

		}		

	}

	public class MyViewPagerAdapter extends PagerAdapter{

		private List<View> mListViews;

		

		public MyViewPagerAdapter(List<View> mListViews) {

			this.mListViews = mListViews;

		}



		@Override

		public void destroyItem(ViewGroup container, int position, Object object) 	{	

			container.removeView(mListViews.get(position));

		}





		@Override

		public Object instantiateItem(ViewGroup container, int position) {			

			 container.addView(mListViews.get(position), 0);

			 return mListViews.get(position);

		}



		@Override

		public int getCount() {			

			return  mListViews.size();

		}

		

		@Override

		public boolean isViewFromObject(View arg0, Object arg1) {			

			return arg0==arg1;

		}

	}

	  public class MyOnPageChangeListener implements OnPageChangeListener{



	    	int one = offset * 2 + bmpW;// 页卡1 -> 页卡2 偏移量	    	

			int two = one * 2;// 页卡1 -> 页卡3 偏移量			

			int three = one * 3;// 页卡1 -> 页卡4偏移量

			public void onPageSelected(int arg0) {



				 Animation animation = new TranslateAnimation(one*currIndex, one*arg0, 0, 0);

				             currIndex = arg0;

				             animation.setFillAfter(true);// True:图片停在动画结束位置

				             animation.setDuration(300);

				             imageView.startAnimation(animation);



			}

			 @Override

			public void onPageScrollStateChanged(int arg0) {						

			}

			 @Override

			public void onPageScrolled(int arg0, float arg1, int arg2) {			

			}



}



}






谢谢大家！！！！！！！！！！！！！！！
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wzysys1617 2014-07-22
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引用 6 楼 heaimnmn 的回复:
[quote=引用 4 楼 wzysys1617 的回复:] [quote=引用 2 楼 heaimnmn 的回复:] 而且为啥不发去移动板块了，，，
我小白，不懂[/quote]能不能把所有红色的都贴出来[/quote] 07-22 10:19:17.697: E/AndroidRuntime(781): FATAL EXCEPTION: main 07-22 10:19:17.697: E/AndroidRuntime(781): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.andyidea.tabdemo/com.andyidea.tabdemo.BActivity}: java.lang.RuntimeException: Unable to start activity ComponentInfo{com.andyidea.tabdemo/com.andyidea.tabdemo.Item_java}: java.lang.NullPointerException 07-22 10:19:17.697: E/AndroidRuntime(781): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1815) 07-22 10:19:17.697: E/AndroidRuntime(781): at android.app.ActivityThread.startActivityNow(ActivityThread.java:1656) 07-22 10:19:17.697: E/AndroidRuntime(781): at android.app.LocalActivityManager.moveToState(LocalActivityManager.java:135) 07-22 10:19:17.697: E/AndroidRuntime(781): at android.app.LocalActivityManager.startActivity(LocalActivityManager.java:347) 07-22 10:19:17.697: E/AndroidRuntime(781): at android.widget.TabHost$IntentContentStrategy.getContentView(TabHost.java:676) 07-22 10:19:17.697: E/AndroidRuntime(781): at android.widget.TabHost.setCurrentTab(TabHost.java:345) 07-22 10:19:17.697: E/AndroidRuntime(781): at android.widget.TabHost.setCurrentTabByTag(TabHost.java:282) 07-22 10:19:17.697: E/AndroidRuntime(781): at com.andyidea.tabdemo.MainTabActivity.onCheckedChanged(MainTabActivity.java:58) 07-22 10:19:17.697: E/AndroidRuntime(781): at android.widget.CompoundButton.setChecked(CompoundButton.java:124) 07-22 10:19:17.697: E/AndroidRuntime(781): at android.widget.CompoundButton.toggle(CompoundButton.java:86) 07-22 10:19:17.697: E/AndroidRuntime(781): at android.widget.RadioButton.toggle(RadioButton.java:72) 07-22 10:19:17.697: E/AndroidRuntime(781): at android.widget.CompoundButton.performClick(CompoundButton.java:98) 07-22 10:19:17.697: E/AndroidRuntime(781): at android.view.View$PerformClick.run(View.java:11934) 07-22 10:19:17.697: E/AndroidRuntime(781): at android.os.Handler.handleCallback(Handler.java:587) 07-22 10:19:17.697: E/AndroidRuntime(781): at android.os.Handler.dispatchMessage(Handler.java:92) 07-22 10:19:17.697: E/AndroidRuntime(781): at android.os.Looper.loop(Looper.java:132) 07-22 10:19:17.697: E/AndroidRuntime(781): at android.app.ActivityThread.main(ActivityThread.java:4123) 07-22 10:19:17.697: E/AndroidRuntime(781): at java.lang.reflect.Method.invokeNative(Native Method) 07-22 10:19:17.697: E/AndroidRuntime(781): at java.lang.reflect.Method.invoke(Method.java:491) 07-22 10:19:17.697: E/AndroidRuntime(781): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841) 07-22 10:19:17.697: E/AndroidRuntime(781): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599) 07-22 10:19:17.697: E/AndroidRuntime(781): at dalvik.system.NativeStart.main(Native Method) 07-22 10:19:17.697: E/AndroidRuntime(781): Caused by: java.lang.RuntimeException: Unable to start activity ComponentInfo{com.andyidea.tabdemo/com.andyidea.tabdemo.Item_java}: java.lang.NullPointerException 07-22 10:19:17.697: E/AndroidRuntime(781): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1815) 07-22 10:19:17.697: E/AndroidRuntime(781): at android.app.ActivityThread.startActivityNow(ActivityThread.java:1656) 07-22 10:19:17.697: E/AndroidRuntime(781): at android.app.LocalActivityManager.moveToState(LocalActivityManager.java:135) 07-22 10:19:17.697: E/AndroidRuntime(781): at android.app.LocalActivityManager.startActivity(LocalActivityManager.java:347) 07-22 10:19:17.697: E/AndroidRuntime(781): at com.andyidea.tabdemo.BActivity.InitViewPager(BActivity.java:44) 07-22 10:19:17.697: E/AndroidRuntime(781): at com.andyidea.tabdemo.BActivity.onCreate(BActivity.java:39) 07-22 10:19:17.697: E/AndroidRuntime(781): at android.app.Activity.performCreate(Activity.java:4397) 07-22 10:19:17.697: E/AndroidRuntime(781): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1048) 07-22 10:19:17.697: E/AndroidRuntime(781): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1779) 07-22 10:19:17.697: E/AndroidRuntime(781): ... 21 more 07-22 10:19:17.697: E/AndroidRuntime(781): Caused by: java.lang.NullPointerException 07-22 10:19:17.697: E/AndroidRuntime(781): at com.andyidea.tabdemo.Item_java.onCreate(Item_java.java:77) 07-22 10:19:17.697: E/AndroidRuntime(781): at android.app.Activity.performCreate(Activity.java:4397) 07-22 10:19:17.697: E/AndroidRuntime(781): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1048) 07-22 10:19:17.697: E/AndroidRuntime(781): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1779) 07-22 10:19:17.697: E/AndroidRuntime(781): ... 29 more 这些，能看清吗？不行我就截图
哎，真难 2014-07-22
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引用 4 楼 wzysys1617 的回复:
[quote=引用 2 楼 heaimnmn 的回复:] 而且为啥不发去移动板块了，，，
我小白，不懂[/quote]能不能把所有红色的都贴出来
姜小白- 2014-07-22
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抱歉，这问题真心不懂
看着是空指针问题，楼主把帖子移到移动板块去吧，那里更专业一些
wzysys1617 2014-07-22
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引用 2 楼 heaimnmn 的回复:
而且为啥不发去移动板块了，，，
我小白，不懂
wzysys1617 2014-07-22
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引用 1 楼 heaimnmn 的回复:
各种邀请，你把logcat贴全部出来，只看那一句不知道是哪里错了，，，
07-22 09:54:15.219: E/InputDispatcher(82): channel '40aaf570 com.andyidea.tabdemo/com.andyidea.tabdemo.MainTabActivity (server)' ~ Consumer closed input channel or an error occurred. events=0x8 07-22 09:54:15.219: E/InputDispatcher(82): channel '40aaf570 com.andyidea.tabdemo/com.andyidea.tabdemo.MainTabActivity (server)' ~ Channel is unrecoverably broken and will be disposed! 就这两个地方是Error ，其他地方是D、I或者W
哎，真难 2014-07-22
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而且为啥不发去移动板块了，，，
哎，真难 2014-07-22
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各种邀请，你把logcat贴全部出来，只看那一句不知道是哪里错了，，，
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