[英]App crashing when passing bundle value between activity and fragment
我試圖通過一個選項列表視圖片段將一些數據從ListView發送到另一個活動。 數據流應該是這樣的:
ListView(選擇選項時)->單選項列表視圖片段(再次選擇選項時)-> AnotherActivity。
將數據從ListView發送到Fragment的代碼:
Bundle b = new Bundle();
b.putString("id", str_projectid);
Projectviewoptions pv = new Projectviewoptions();
pv.setArguments(b);
Projectviewoptions newFragment = new Projectviewoptions();
newFragment.show(getFragmentManager(), "projectoptions");
接收數據,然后將其發送到其他活動的代碼片段類:
public class Projectviewoptions extends DialogFragment {
String[] option_array = new String[] {"Project details","Edit","Delete","Mark Done"};
Bundle idbundle = getArguments();
String myid= idbundle.getString("id");
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
builder.setTitle("Options")
.setItems(option_array, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
switch(which) {
case 0: Intent intent = new Intent(getActivity(),ViewProjectDetails.class);
intent.putExtra("id", myid);
startActivity(intent);
break;
}
}
});
return builder.create();
}
}
OtherActivity中的代碼,用於接收片段傳遞的數據:
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_view_project_details);
String id = getIntent().getExtras().getString("id");
Toast.makeText(this, id, Toast.LENGTH_LONG).show();
}
問題:當我從ListView中選擇一個選項時,應用程序崩潰。 如果我刪除了處理數據傳遞的代碼,則該應用程序可以正常運行。 也就是說,如果您在ListView中刪除以下代碼:
/*Bundle b = new Bundle();
b.putString("id", str_projectid);
Projectviewoptions pv = new Projectviewoptions();
pv.setArguments(b);*/
以及以下片段類中的內容:
//Bundle idbundle = getArguments();
//String myid= idbundle.getString("id");
這是LogCat:
12-30 23:21:09.620: W/dalvikvm(7406): threadid=1: thread exiting with uncaught
exception (group=0x409c01f8)
12-30 23:21:09.653: E/AndroidRuntime(7406): FATAL EXCEPTION: main
12-30 23:21:09.653: E/AndroidRuntime(7406): java.lang.NullPointerException
12-30 23:21:09.653: E/AndroidRuntime(7406): at
com.kk.project.Projectviewoptions.<init>(Projectviewoptions.java:14)
12-30 23:21:09.653: E/AndroidRuntime(7406): at
com.kk.project.ProjectExplorer.onListItemClick(ProjectExplorer.java:53)
12-30 23:21:09.653: E/AndroidRuntime(7406): at
android.app.ListActivity$2.onItemClick(ListActivity.java:319)
12-30 23:21:09.653: E/AndroidRuntime(7406): at
android.widget.AdapterView.performItemClick(AdapterView.java:292)
12-30 23:21:09.653: E/AndroidRuntime(7406): at
android.widget.AbsListView.performItemClick(AbsListView.java:1058)
12-30 23:21:09.653: E/AndroidRuntime(7406): at
android.widget.AbsListView$PerformClick.run(AbsListView.java:2514)
12-30 23:21:09.653: E/AndroidRuntime(7406): at
android.widget.AbsListView$1.run(AbsListView.java:3168)
12-30 23:21:09.653: E/AndroidRuntime(7406): at
android.os.Handler.handleCallback(Handler.java:605)
12-30 23:21:09.653: E/AndroidRuntime(7406): at
android.os.Handler.dispatchMessage(Handler.java:92)
12-30 23:21:09.653: E/AndroidRuntime(7406): at
android.os.Looper.loop(Looper.java:137)
12-30 23:21:09.653: E/AndroidRuntime(7406): at
android.app.ActivityThread.main(ActivityThread.java:4424)
12-30 23:21:09.653: E/AndroidRuntime(7406): at
java.lang.reflect.Method.invokeNative(Native Method)
12-30 23:21:09.653: E/AndroidRuntime(7406): at
java.lang.reflect.Method.invoke(Method.java:511)
12-30 23:21:09.653: E/AndroidRuntime(7406): at
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
12-30 23:21:09.653: E/AndroidRuntime(7406): at
com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
12-30 23:21:09.653: E/AndroidRuntime(7406): at
dalvik.system.NativeStart.main(Native Method)
您不能在任何方法之外訪問Fragment的參數,只需將這段代碼移到onCreateDialog()
:
Bundle idbundle;
String myid;
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
idbundle = getArguments();
myid = idbundle.getString("id");
...
問題是getArguments();
當您嘗試在Fragment的生命周期開始之前訪問它時,返回null,因此idbundle.getString()
是NPE。
加成
您newFragment
同一片段創建兩個不同的副本,分別名為pv
和newFragment
,應顯示pv
並完全刪除newFragment
:
Bundle b = new Bundle();
b.putString("id", str_projectid);
Projectviewoptions pv = new Projectviewoptions();
pv.setArguments(b);
pv.show(getFragmentManager(), "projectoptions");
Projectviewoptions newFragment = new Projectviewoptions(); newFragment.show(getFragmentManager(), "projectoptions");
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.