【发布时间】：2016-08-04 02:16:09
【问题描述】：
我无法将意图发送到片段。我正在尝试将意图从一个类发送到另一个类，然后为片段设置参数。然后在片段中，我想要一个 switch 语句根据争论的值将数据设置到回收器视图。
这是第一个活动（我只展示了我设置意图的 2 个子位置，实际上还有更多）：
expandableListView.setOnChildClickListener(new ExpandableListView.OnChildClickListener() {
@Override
public boolean onChildClick(ExpandableListView parent, View v, int groupPosition, int childPosition, long id) {
if (groupPosition == 0) {
if (childPosition == 0) {
Intent intent = new Intent(getApplicationContext(), WorkoutDaysActivity.class);
intent.putExtra("workout", "w29w1");
startActivity(intent);
}
if (childPosition == 1) {
Intent intent = new Intent(getApplicationContext(), WorkoutDaysActivity.class);
intent.putExtra("workout", "w29w1");
startActivity(intent);
}
这里是创建片段的地方，也是我尝试设置参数的地方：
public class WorkoutDaysActivity extends BaseActivity{
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.workout_days);
mToolBar = activateToolbar();
setUpNavigationDrawer();
ViewPager vp = (ViewPager) findViewById(R.id.view_pager);
this.addPages(vp);
TabLayout tabLayout = (TabLayout) findViewById(R.id.tab_layout);
// tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);
tabLayout.setupWithViewPager(vp);
tabLayout.setOnTabSelectedListener(listener(vp));
}
private void addPages(ViewPager pager) {
MyFragPagerAdapter adapter = new MyFragPagerAdapter(getSupportFragmentManager());
Intent intent = getIntent();
String workout = intent.getStringExtra("workout");
Bundle args = new Bundle();
args.putString("workout", workout);
MondayFragment mondayFragment = new MondayFragment();
mondayFragment.setArguments(args);
adapter.addPage(mondayFragment);
WedFragment wedFragment = new WedFragment();
wedFragment.setArguments(args);
adapter.addPage(wedFragment);
FridayFragment fridayFragment = new FridayFragment();
fridayFragment.setArguments(args);
adapter.addPage(fridayFragment);
最后是我尝试使用 switch 语句设置值的三个片段类之一：
public class WedFragment extends Fragment {
Bundle args = getArguments();
String workout3 = args.getString("workout");
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.wed_fragment, null);
// //RECYCLERVIEW
RecyclerView rv = (RecyclerView) view.findViewById(R.id.mRecyclerWed);
rv.setLayoutManager(new LinearLayoutManager(this.getActivity()));
rv.setAdapter(new MyRecyclerAdapter(this.getActivity(), getWedWorkout()));
return view;
}
private ArrayList<Workout> getWedWorkout() {
//COLLECTION OF MONDAY WORKOUT
ArrayList<Workout> workout = new ArrayList<>();
switch(workout3) {
case "w29w1" : {
Workout workouts = new Workout("Bench", "60", "6", "155", false);
//ADD TO COLLECTION
workout.add(workouts);
workouts = new Workout("Bench", "70", "5", "175", false);
workout.add(workouts);
break;}
case "w29w2" :{
Workout workouts = new Workout("Squat", "60", "6", "155", false);
//ADD TO COLLECTION
workout.add(workouts);
workouts = new Workout("Squat", "70", "5", "175", false);
workout.add(workouts);
break;}
} return workout;
这是导致应用程序崩溃的错误：
08-03 13:53:11.917 32143-32143/com.bestworkouts.sheikoworkout E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.bestworkouts.sheikoworkout, PID: 32143
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.bestworkouts.sheikoworkout/com.bestworkouts.sheikoworkout.WorkoutDaysActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.os.Bundle.getString(java.lang.String)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3254)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3350)
at android.app.ActivityThread.access$1100(ActivityThread.java:222)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1795)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:158)
at android.app.ActivityThread.main(ActivityThread.java:7229)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.os.Bundle.getString(java.lang.String)' on a null object reference
at com.bestworkouts.sheikoworkout.Fragments.WedFragment.<init>(WedFragment.java:24)
at com.bestworkouts.sheikoworkout.WorkoutDaysActivity.addPages(WorkoutDaysActivity.java:47)
at com.bestworkouts.sheikoworkout.WorkoutDaysActivity.onCreate(WorkoutDaysActivity.java:27)
at android.app.Activity.performCreate(Activity.java:6876)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1135)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3207)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3350)
at android.app.ActivityThread.access$1100(ActivityThread.java:222)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1795)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:158)
at android.app.ActivityThread.main(ActivityThread.java:7229)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)
WedFragment.java:24 是这一行：
String workout3 = args.getString("workout");
WorkoutDaysActivity.java:47 是这一行：
WedFragment wedFragment = new WedFragment();
WorkoutDaysActivity.java:27 是这一行：
tabLayout.setupWithViewPager(vp);
【问题讨论】：
-
您的活动是否有另一个入口点？我的意思是，您没有额外设置“锻炼”的另一个意图。到目前为止找不到任何错误，请检查您缺少该字符串的位置。
-
下面的答案有效！不得不切换 Fragment 类中的一些代码！
标签： android android-fragments android-intent arguments android-switch