Android Imageprieview显示空值
这是主要的活动代码Android Imageprieview显示空值,android,performance,android-layout,Android,Performance,Android Layout,这是主要的活动代码 public class MyTestActivity extends Activity { private static final int MAX_PAGES = 10; private static final String IMAGE_RESOURCE = null; private int num_pages = 1; private int image=1; @Overr
public class MyTestActivity extends Activity {
private static final int MAX_PAGES = 10;
private static final String IMAGE_RESOURCE = null;
private int num_pages = 1;
private int image=1;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
final ViewPagerParallax pager = (ViewPagerParallax) findViewById(R.id.pager);
pager.set_max_pages(MAX_PAGES);
pager.setBackgroundAsset(R.raw.building);
pager.setAdapter(new my_adapter());
int i=0;
for(i=0;i<MAX_PAGES;i++)
{
num_pages = Math.min(num_pages+1, MAX_PAGES);
pager.getAdapter().notifyDataSetChanged();
}
if (savedInstanceState!=null) {
image=savedInstanceState.getInt(IMAGE_RESOURCE, R.raw.sanfran);
}
}
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putInt("image", image);
final ViewPagerParallax pager = (ViewPagerParallax) findViewById(R.id.pager);
outState.putInt("current_page", pager.getCurrentItem());
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.home:
break;
case R.id.landmark:
break;
case R.id.futureproof:
break;
case R.id.luxury:
break;
case R.id.theinsidestory:
break;
case R.id.floorplan:
break;
case R.id.layout:
break;
}
return super.onOptionsItemSelected(item);
}
private class my_adapter extends PagerAdapter {
@Override
public int getCount() {
return num_pages;
}
@Override
public boolean isViewFromObject(View view, Object o) {
return view == o;
}
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
container.removeView((View)object);
}
@Override
public Object instantiateItem(ViewGroup container, int position) {
View new_view=null;
LayoutInflater inflater = getLayoutInflater();
new_view = inflater.inflate(R.layout.page, null);
ImageView imgPreview=(ImageView) new_view.findViewById(R.id.imageView1);
imgPreview.setVisibility(View.VISIBLE);
imgPreview.setImageResource(R.raw.sanfran);
container.addView(new_view);
return new_view;
}
}
}
E/AndroidRuntime(7141): FATAL EXCEPTION: main
E/AndroidRuntime(7141): java.lang.NullPointerException
E/AndroidRuntime(7141): at com.matthieu.MyTestActivity$my_adapter.instantiateItem(MyTestActivity.java:105)
E/AndroidRuntime(7141): at android.support.v4.view.ViewPager.addNewItem(ViewPager.java:801)
E/AndroidRuntime(7141): at android.support.v4.view.ViewPager.populate(ViewPager.java:930)
E/AndroidRuntime(7141): at android.support.v4.view.ViewPager.populate(ViewPager.java:881)
E/AndroidRuntime(7141): at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1366)
E/AndroidRuntime(7141): at android.view.View.measure(View.java:15635)
E/AndroidRuntime(7141): at android.widget.LinearLayout.measureVertical(LinearLayout.java:850)
E/AndroidRuntime(7141): at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
E/AndroidRuntime(7141): at android.view.View.measure(View.java:15635)
E/AndroidRuntime(7141): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4919)
E/AndroidRuntime(7141): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
E/AndroidRuntime(7141): at android.view.View.measure(View.java:15635)
E/AndroidRuntime(7141): at android.widget.LinearLayout.measureVertical(LinearLayout.java:850)
E/AndroidRuntime(7141): at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
E/AndroidRuntime(7141): at android.view.View.measure(View.java:15635)
E/AndroidRuntime(7141): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4919)
E/AndroidRuntime(7141): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
E/AndroidRuntime(7141): at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2200)
E/AndroidRuntime(7141): at android.view.View.measure(View.java:15635)
E/AndroidRuntime(7141): at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2165)
E/AndroidRuntime(7141): at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1249)
E/AndroidRuntime(7141): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1443)
E/AndroidRuntime(7141): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1139)
E/AndroidRuntime(7141): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4872)
E/AndroidRuntime(7141): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:776)
E/AndroidRuntime(7141): at android.view.Choreographer.doCallbacks(Choreographer.java:579)
E/AndroidRuntime(7141): at android.view.Choreographer.doFrame(Choreographer.java:548)
E/AndroidRuntime(7141): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:762)
E/AndroidRuntime(7141): at android.os.Handler.handleCallback(Handler.java:800)
E/AndroidRuntime(7141): at android.os.Handler.dispatchMessage(Handler.java:100)
E/AndroidRuntime(7141): at android.os.Looper.loop(Looper.java:194)
E/AndroidRuntime(7141): at android.app.ActivityThread.main(ActivityThread.java:5371)
E/AndroidRuntime(7141): at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(7141): at java.lang.reflect.Method.invoke(Method.java:525)
E/AndroidRuntime(7141): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
E/AndroidRuntime(7141): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
E/AndroidRuntime(7141): at dalvik.system.NativeStart.main(Native Method)
这显然意味着名为“页面”的版面中没有任何名为imageView1的ImageView组件，因此请检查版面文件一次。请提供logcat错误。是的，它没有一个允许我更改，这就是它为空的原因，只需在那里添加一个带有所需名称的imageview。谢谢，伙计，但我仍然不明白你是如何得到这个cz的，我在main.xml中添加了这个cz，而不是在page.xml中添加的。很简单，你说什么是null，我算出了rest，不管怎样，我看到你已经发布了你的main.xml，它包含了一个你试图在适配器中引用的带有名称的图像视图，这给了我可能错误的线索。你能帮我解决另一个问题吗，现在当我滑动两个图像时。jpg（是背景）和sanfran.jpg是上面显示的图像。我希望sanfran.jpg是静止的，而建筑是移动的。如何做到这一点，即使你可以转发给我一个教程，有什么想法？？？
ImageView imgPreview=(ImageView) new_view.findViewById(R.id.imageView1);
E/AndroidRuntime(7141): FATAL EXCEPTION: main
E/AndroidRuntime(7141): java.lang.NullPointerException
E/AndroidRuntime(7141): at com.matthieu.MyTestActivity$my_adapter.instantiateItem(MyTestActivity.java:105)
E/AndroidRuntime(7141): at android.support.v4.view.ViewPager.addNewItem(ViewPager.java:801)
E/AndroidRuntime(7141): at android.support.v4.view.ViewPager.populate(ViewPager.java:930)
E/AndroidRuntime(7141): at android.support.v4.view.ViewPager.populate(ViewPager.java:881)
E/AndroidRuntime(7141): at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1366)
E/AndroidRuntime(7141): at android.view.View.measure(View.java:15635)
E/AndroidRuntime(7141): at android.widget.LinearLayout.measureVertical(LinearLayout.java:850)
E/AndroidRuntime(7141): at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
E/AndroidRuntime(7141): at android.view.View.measure(View.java:15635)
E/AndroidRuntime(7141): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4919)
E/AndroidRuntime(7141): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
E/AndroidRuntime(7141): at android.view.View.measure(View.java:15635)
E/AndroidRuntime(7141): at android.widget.LinearLayout.measureVertical(LinearLayout.java:850)
E/AndroidRuntime(7141): at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
E/AndroidRuntime(7141): at android.view.View.measure(View.java:15635)
E/AndroidRuntime(7141): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4919)
E/AndroidRuntime(7141): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
E/AndroidRuntime(7141): at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2200)
E/AndroidRuntime(7141): at android.view.View.measure(View.java:15635)
E/AndroidRuntime(7141): at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2165)
E/AndroidRuntime(7141): at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1249)
E/AndroidRuntime(7141): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1443)
E/AndroidRuntime(7141): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1139)
E/AndroidRuntime(7141): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4872)
E/AndroidRuntime(7141): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:776)
E/AndroidRuntime(7141): at android.view.Choreographer.doCallbacks(Choreographer.java:579)
E/AndroidRuntime(7141): at android.view.Choreographer.doFrame(Choreographer.java:548)
E/AndroidRuntime(7141): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:762)
E/AndroidRuntime(7141): at android.os.Handler.handleCallback(Handler.java:800)
E/AndroidRuntime(7141): at android.os.Handler.dispatchMessage(Handler.java:100)
E/AndroidRuntime(7141): at android.os.Looper.loop(Looper.java:194)
E/AndroidRuntime(7141): at android.app.ActivityThread.main(ActivityThread.java:5371)
E/AndroidRuntime(7141): at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(7141): at java.lang.reflect.Method.invoke(Method.java:525)
E/AndroidRuntime(7141): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
E/AndroidRuntime(7141): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
E/AndroidRuntime(7141): at dalvik.system.NativeStart.main(Native Method)
LayoutInflater inflater = getLayoutInflater();
new_view = inflater.inflate(R.layout.page, null);
ImageView imgPreview=(ImageView) new_view.findViewById(R.id.imageView1); // this line as per you is null