我是Android Tv开发的新手，我需要将一个字符串从它所属的相同活动传递给MainFragment。 这是我的MainActivity代码：
public class MainActivity extends Activity {
EditText search_query;
private static String user_query = "";
Bundle query_data;
ImageView action_search, action_delete;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.d("TAG", "Main-act-created");
setContentView(R.layout.activity_main);
query_data = new Bundle();
query_data.putString("SEARCHQUERY",user_query);
search_query = (EditText)findViewById(R.id.search_query);
action_search = (ImageView)findViewById(R.id.action_search);
action_delete = (ImageView)findViewById(R.id.action_delete);
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
Fragment fragment = new MainFragment();
fragment.setArguments(query_data);
fragmentTransaction.add(fragment,"MainFragment");
fragmentTransaction.commit();
Thread t = new Thread(new Runnable() {
@Override
public void run() {
SharedPreferences getPrefs = PreferenceManager
.getDefaultSharedPreferences(getBaseContext());
boolean isFirstStart = getPrefs.getBoolean("firstStart", true);
if (isFirstStart) {
Intent i = new Intent(MainActivity.this, BoardingActivity.class);
startActivity(i);
SharedPreferences.Editor e = getPrefs.edit();
e.putBoolean("firstStart", false);
e.apply();
}
}
});
// Start the thread
t.start();
action_search.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
respondToSearch();
}
});
action_delete.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
}
});
}
public void respondToSearch(){
user_query = search_query.getText().toString();
//pass the query to MainFragment
query_data.putString("SEARCHQUERY",user_query);
Fragment fragment = new MainFragment();
fragment.setArguments(query_data);
}
}
这是活动的布局：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_height="match_parent"
android:layout_width="match_parent"
android:id="@+id/main_frame"
android:background="#ffffff"
android:layout_margin="2dp"
android:padding="2dp"
android:orientation="vertical">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="7.5"
android:background="#B71C1C"
android:alpha="0.9"
android:layout_marginBottom="3dp"
android:orientation="horizontal">
<EditText
android:layout_width="match_parent"
android:layout_height="match_parent"
android:hint="Search"
android:id="@+id/search_query"
android:textSize="25sp"
android:layout_weight="1"
android:layout_marginLeft="2dp"
android:layout_marginTop="2dp"
android:layout_marginBottom="2dp"/>
<ImageView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#B71C1C"
android:src="@drawable/close"
android:layout_marginTop="15dp"
android:layout_marginBottom="15dp"
android:layout_marginRight="15dp"
android:id="@+id/action_delete"
android:layout_weight="5"/>
<ImageView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:src="@drawable/search"
android:background="#ffffff"
android:id="@+id/action_search"
android:layout_weight="5"/>
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1">
<FrameLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:layout_width="250dp"
android:layout_height="120dp"
android:src="@drawable/banner"
android:layout_gravity="right"
android:gravity="right"
android:layout_margin="3dp"
android:padding="0dp" />
<fragment xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/main_browse_fragment"
android:name="in.silive.mytvapplication.Fragments.MainFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".Activities.MainActivity"
tools:deviceIds="tv"
tools:ignore="MergeRootFrame" />
</FrameLayout>
</LinearLayout>
</LinearLayout>
以下是我在MainFragment中检索字符串的方法：
@Override
public void onActivityCreated(Bundle savedInstanceState) {
Log.d(TAG, "onCreate-MainFragment");
super.onActivityCreated(savedInstanceState);
context = getActivity();
prepareBackgroundManager();
Log.d(TAG, "onCreate-MainFragment_background prepared");
sbundle = getArguments().getBundle("SEARCHQUERY");
if(sbundle!=null){
user_search = this.getArguments().getString("SEARCHQUERY");
Log.d("TAG","user search : "+user_search);
}
setupUIElements();
Log.d(TAG, "onCreate-MainFragment_ui elements placed");
mRowsAdapter = new ArrayObjectAdapter(new ListRowPresenter());
for (int j = 0; j < 5; j++) {
if (j == 0) {
sprogressDialog = new ProgressDialog(context);
sprogressDialog.setMessage("Loading");
sprogressDialog.show();
}
final int finalJ = j;
new FetchData(j, context, api_url[j], new OnTaskComplete() {
@Override
public void OnTaskComplete() {
loadRows(i);
if (finalJ == 4 && sprogressDialog.isShowing())
sprogressDialog.dismiss();
}
}).execute();
}
dataLoaded = true;
//loadRows();
Log.d(TAG, "onCreate-MainFragment_row adapter implemented");
setupEventListeners();
Log.d(TAG, "onCreate-MainFragment_event listeners applied");
}
我收到此错误：
Process: in.silive.mytvapplication, PID: 6417
java.lang.RuntimeException: Unable to start activity ComponentInfo{in.silive.mytvapplication/in.silive.mytvapplication.Activities.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.os.Bundle android.os.Bundle.getBundle(java.lang.String)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2665)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.os.Bundle android.os.Bundle.getBundle(java.lang.String)' on a null object reference
at in.silive.mytvapplication.Fragments.MainFragment.onActivityCreated(MainFragment.java:99)
at android.app.Fragment.performActivityCreated(Fragment.java:2362)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1014)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1171)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1153)
at android.app.FragmentManagerImpl.dispatchActivityCreated(FragmentManager.java:2039)
at android.app.FragmentController.dispatchActivityCreated(FragmentController.java:176)
at android.app.Activity.performCreateCommon(Activity.java:6673)
at android.app.Activity.performCreate(Activity.java:6681)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2618)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
这是行号：99。（sbundle = getArguments().getBundle("QUERYSEARCH");）
答案 0 :(得分：0)
使用Bundle传递值
public void respondToSearch(){
user_query = search_query.getText().toString();
Fragment fragment = new MainFragment();
Bundle bundle = new Bundle();
bundle.putString("QUERYSEARCH", user_query);
fragment.setArguments(bundle);
}
并从Bundle中读取值
Bundle bundle = getArguments();
String sbundle = bundle.getString("QUERYSEARCH");
在您的代码中，您将密钥值作为SEARCHQUERY发送，并使用QUERYSEARCH键读取值。