我首先要说的是我是Android编程的新手，在阅读了无数的帖子后，我仍然无法确定我在尝试时做错了什么。将一些参数从Fragment传递给Activity，任何帮助都会非常有用。
我的活动课程：
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
public static final MasterFragment newInstance(String numberOfItems) {
MasterFragment masterFragment = new MasterFragment();
Bundle bundle = new Bundle();
bundle.putString("numberOfItems", numberOfItems);
masterFragment.setArguments(bundle);
return masterFragment;
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState != null) {
MasterFragment masterFragment = new MasterFragment();
masterFragment.setArguments(getIntent().getExtras());
}
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
/*getting some buttons here
*/
//not sure if relevant, but just in case I'll add this here too
getSupportActionBar().setDisplayShowHomeEnabled(true);
getSupportActionBar().setIcon(R.drawable.ic_menu_white_24dp);
if (toolbar != null) {
toolbar.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
SlidingPaneLayout mSlidingLayout;
mSlidingLayout = (SlidingPaneLayout) findViewById(R.id.mainSlidingPaneLayout);
if (mSlidingLayout.isOpen()) {
mSlidingLayout.closePane();
getSupportActionBar().setIcon(R.drawable.ic_menu_white_24dp);
} else {
mSlidingLayout.openPane();
getSupportActionBar().setIcon(R.drawable.ic_arrow_back_white_24dp);
}
}
});
}
}
@Override
public void onClick(View v) {
Intent intent = new Intent(getApplicationContext(), ProductsScrollingActivity
.class);
ArrayList<String> products = new ArrayList<String>();
switch (v.getId()) {
case R.id.baby: {
//getting the products ArrayList here
break;
}
}
intent.putExtra("products", products);
startActivity(intent);
}
}
My Fragment课程：
public class MasterFragment extends ListFragment {
String noOfItems;
@Override
public View onCreateView (LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_master, container);
noOfItems = getArguments().getString("numberOfItems", "0");
setListAdapter(new MenuListAdapter(R.layout.row_menu_action_item, getActivity(), MenuActionItem.values(), noOfItems));
return view;
}
}
我的content_main.xml：
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.SlidingPaneLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
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"
android:background="#ffffff"
android:orientation="horizontal"
android:id="@+id/mainSlidingPaneLayout"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:context="com.example.MainActivity"
tools:showIn="@layout/activity_main">
<!--Master fragment-->
<fragment
android:id="@+id/fragment_master"
android:name="com.example.MasterFragment"
android:layout_width="@dimen/mini_drawer_fragment_width"
android:layout_height="match_parent"
tools:layout="@layout/fragment_master">
</fragment>
<!-- A ScrollView goes here with some other stuff-->
</android.support.v4.widget.SlidingPaneLayout>
堆栈追踪：
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example/com.example.MainActivity}: android.view.InflateException: Binary XML file line #25: Binary XML file line #20: Error inflating class fragment
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: android.view.InflateException: Binary XML file line #25: Binary XML file line #20: Error inflating class fragment
at android.view.LayoutInflater.inflate(LayoutInflater.java:539)
at android.view.LayoutInflater.inflate(LayoutInflater.java:423)
at android.view.LayoutInflater.inflate(LayoutInflater.java:374)
at android.support.v7.app.AppCompatDelegateImplV7.setContentView(AppCompatDelegateImplV7.java:256)
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:109)
at com.example.MainActivity.onCreate(MainActivity.java:59)
at android.app.Activity.performCreate(Activity.java:6237)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: android.view.InflateException: Binary XML file line #20: Error inflating class fragment
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:782)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:704)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:835)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:798)
at android.view.LayoutInflater.parseInclude(LayoutInflater.java:971)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:831)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:798)
at android.view.LayoutInflater.inflate(LayoutInflater.java:515)
at android.view.LayoutInflater.inflate(LayoutInflater.java:423)
at android.view.LayoutInflater.inflate(LayoutInflater.java:374)
at android.support.v7.app.AppCompatDelegateImplV7.setContentView(AppCompatDelegateImplV7.java:256)
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:109)
at com.example.MainActivity.onCreate(MainActivity.java:59)
at android.app.Activity.performCreate(Activity.java:6237)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.os.Bundle.getString(java.lang.String, java.lang.String)' on a null object reference
at com.example.MasterFragment.onCreateView(MasterFragment.java:26)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:1962)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1036)
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:754)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:704)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:835)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:798)
at android.view.LayoutInflater.parseInclude(LayoutInflater.java:971)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:831)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:798)
at android.view.LayoutInflater.inflate(LayoutInflater.java:515)
at android.view.LayoutInflater.inflate(LayoutInflater.java:423)
at android.view.LayoutInflater.inflate(LayoutInflater.java:374)
at android.support.v7.app.AppCompatDelegateImplV7.setContentView(AppCompatDelegateImplV7.java:256)
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:109)
at com.example.MainActivity.onCreate(MainActivity.java:59)
at android.app.Activity.performCreate(Activity.java:6237)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
答案 0 :(得分：1)
当您在XML中定义片段时，您无法在片段膨胀之前在片段上设置参数 - 因此在onViewCreated中的片段代码中，getArguments（）为null，这会导致此崩溃。如果要为片段添加参数，请将XML中的<fragment>标记替换为FrameLayout，在活动中定义片段（正如您已经做的那样），并使用FragmentManager将其添加到FrameLayout：
getSupportFragmentManager().beginTransaction()
.add(R.id.fragment_container, /*id of your frame layout*/
fragment /*instance of the fragment created in your activity*/)
.commit();