当我尝试运行我的Android应用程序时出现此错误：
Process: com.example.ronen.sunplantnew, PID: 28608
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.ronen.sunplantnew/com.example.ronen.sunplantnew.MainActivity}: android.view.InflateException: Binary XML file line #13: Error inflating class fragment
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2325)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
Caused by: android.view.InflateException: Binary XML file line #13: Error inflating class fragment
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:763)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:806)
at android.view.LayoutInflater.inflate(LayoutInflater.java:504)
at android.view.LayoutInflater.inflate(LayoutInflater.java:414)
at android.view.LayoutInflater.inflate(LayoutInflater.java:365)
at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:378)
at android.app.Activity.setContentView(Activity.java:2145)
at com.example.ronen.sunplantnew.MainActivity.onCreate(MainActivity.java:17)
at android.app.Activity.performCreate(Activity.java:5990)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
at com.example.ronen.sunplantnew.HomeScreen.onCreate(HomeScreen.java:59)
at android.support.v4.app.Fragment.performCreate(Fragment.java:1939)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1029)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1226)
at android.support.v4.app.FragmentManagerImpl.addFragment(FragmentManager.java:1328)
at android.support.v4.app.FragmentManagerImpl.onCreateView(FragmentManager.java:2284)
at android.support.v4.app.FragmentController.onCreateView(FragmentController.java:111)
at android.support.v4.app.FragmentActivity.dispatchFragmentsOnCreateView(FragmentActivity.java:314)
at android.support.v4.app.BaseFragmentActivityHoneycomb.onCreateView(BaseFragmentActivityHoneycomb.java:31)
at android.support.v4.app.FragmentActivity.onCreateView(FragmentActivity.java:79)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:733)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:806)
at android.view.LayoutInflater.inflate(LayoutInflater.java:504)
at android.view.LayoutInflater.inflate(LayoutInflater.java:414)
at android.view.LayoutInflater.inflate(LayoutInflater.java:365)
at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:378)
at android.app.Activity.setContentView(Activity.java:2145)
at com.example.ronen.sunplantnew.MainActivity.onCreate(MainActivity.java:17)
at android.app.Activity.performCreate(Activity.java:5990)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
主要活动java文件（MainActivity.java）
public class MainActivity extends FragmentActivity implements HomeScreen.OnFragmentInteractionListener, LightTest.OnFragmentInteractionListener {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
@Override
public void onFragmentInteraction(Uri uri) {
}
}
主要活动xml文件（activity_main.xml）
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/fragment_container"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.ronen.sunplantnew.MainActivity">
<fragment class="com.example.ronen.sunplantnew.HomeScreen"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/home"/>
</RelativeLayout>
HomeScreen java文件（HomeScreen.java）：
public class HomeScreen extends android.support.v4.app.Fragment {
private Button newTest;
private Button lastTests;
private Button plants;
private Button about;
private OnFragmentInteractionListener mListener;
public HomeScreen() {
// Required empty public constructor
}
/**
* Use this factory method to create a new instance of
* this fragment using the provided parameters.
*
* @return A new instance of fragment HomeScreen.
*/
public static HomeScreen newInstance() {
HomeScreen fragment = new HomeScreen();
Bundle args = new Bundle();
fragment.setArguments(args);
return fragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
newTest=(Button)getActivity().findViewById(R.id.newTest);
lastTests=(Button)getActivity().findViewById(R.id.lastTests);
plants=(Button)getActivity().findViewById(R.id.plants);
about=(Button)getActivity().findViewById(R.id.about);
newTest.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
toLightTest();
}
});
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_home_screen, container, false);
}
// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(Uri uri) {
if (mListener != null) {
mListener.onFragmentInteraction(uri);
}
}
@Override
public void onAttach(Context context) {
super.onAttach(context);
if (context instanceof OnFragmentInteractionListener) {
mListener = (OnFragmentInteractionListener) context;
} else {
throw new RuntimeException(context.toString()
+ " must implement OnFragmentInteractionListener");
}
}
@Override
public void onDetach() {
super.onDetach();
mListener = null;
}
/**
* This interface must be implemented by activities that contain this
* fragment to allow an interaction in this fragment to be communicated
* to the activity and potentially other fragments contained in that
* activity.
* <p/>
* See the Android Training lesson <a href=
* "http://developer.android.com/training/basics/fragments/communicating.html"
* >Communicating with Other Fragments</a> for more information.
*/
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
void onFragmentInteraction(Uri uri);
}
public void toLightTest(){
// Create new fragment and transaction
Fragment newFragment = new LightTest();
FragmentTransaction transaction = getFragmentManager().beginTransaction();
// Replace whatever is in the fragment_container view with this fragment,
// and add the transaction to the back stack
transaction.replace(R.id.fragment_container, newFragment);
transaction.addToBackStack(null);
// Commit the transaction
transaction.commit();
}
}
HomeScreen xml文件（fragment_home_screen.xml）：
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.ronen.sunplantnew.HomeScreen">
<ImageView
android:layout_width="150dp"
android:layout_height="wrap_content"
android:id="@+id/imageView2"
android:src="@drawable/sun_plant"
android:layout_centerHorizontal="true"
android:layout_gravity="center" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="About"
android:id="@+id/about"
android:layout_alignBottom="@+id/imageView2"
android:layout_centerHorizontal="true"
android:layout_gravity="center_horizontal|bottom" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Last Tests"
android:id="@+id/lastTests"
android:layout_below="@+id/newTest"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true"
android:layout_marginTop="41dp"
android:layout_gravity="left|center_vertical" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="New LightTest"
android:id="@+id/newTest"
android:layout_alignTop="@+id/imageView2"
android:layout_alignRight="@+id/imageView2"
android:layout_alignEnd="@+id/imageView2"
android:layout_marginTop="45dp"
android:layout_gravity="center_horizontal|top" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Plants Info"
android:id="@+id/plants"
android:layout_alignTop="@+id/lastTests"
android:layout_toLeftOf="@+id/newTest"
android:layout_toStartOf="@+id/newTest"
android:layout_gravity="right|center_vertical" />
我需要做些什么才能解决此错误？
答案 0 :(得分：1)
您试图在newTest中找到Activity，但它位于HomeScreen内。
请改为尝试：
<强> HomeScreen.java
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_home_screen, container, false);
newTest = (Button)view.findViewById(R.id.newTest);
lastTests = (Button)view.findViewById(R.id.lastTests);
plants = (Button)view.findViewById(R.id.plants);
about=(Button)view.findViewById(R.id.about);
newTest.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
toLightTest();
}
});
return view;
}