方向モードごとに異なるレイアウトを持つアプリを構築したいと考えています。だから私は自分のプロジェクトを同様にビルドしました android tutorial [example here] . しかし、1 つの違いを除いて、このチュートリアルでは、さまざまな方向モード (横向き、縦向きなど) が必要な場合に、さまざまなサイズ (通常と大) を作成していました。そして今、私はNullPointerExceptionオリエンテーションの変更中に取得しています。これが私のコードです：
見出しフラグメント:
public class HeadlinesFragment extends ListFragment {
OnHeadlineSelectedListener HeadlinesCallback;
List<Person> personLista = new ArrayList<Person>();
public interface OnHeadlineSelectedListener {
public void onArticleSelected(Person person);
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
int layout = Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB ?
android.R.layout.simple_list_item_activated_1 : android.R.layout.simple_list_item_1;
//TESTOWE WYPENIENIE
for(int i=0; i<10; i++){
personLista.add(new Person("Imie"+i+"Nazwisko"+i,"email"+i+"@example"+i+".com"));
}
String[] niceTime = new String[personLista.size()];
for(int i=0; i<personLista.size(); i++){
niceTime[i] = personLista.get(i).getName();
}
//KONIEC
setListAdapter(new ArrayAdapter<String>(getActivity(), layout, niceTime));
}
@Override
public void onStart() {
super.onStart();
// When in two-pane layout, set the listview to highlight the selected list item
// (We do this during onStart because at the point the listview is available.)
if (getFragmentManager().findFragmentById(R.id.person_view) != null) {
getListView().setChoiceMode(ListView.CHOICE_MODE_SINGLE);
}
}
@Override
public void onAttach(Activity activity){
super.onAttach(activity);
try{
HeadlinesCallback = (OnHeadlineSelectedListener)activity;
}catch(ClassCastException e){
throw new ClassCastException(activity.toString()
+ " have to implement OnHeadlineSelectedListener");
}
}
@Override
public void onListItemClick(ListView l, View v, int position, long id){
HeadlinesCallback.onArticleSelected(personLista.get(position));
getListView().setItemChecked(position, true);
}
}
人物フラグメント:
public class PersonFragment extends Fragment{
public static Person person;
ImageView icon;
TextView text1;
TextView text2;
TextView text3;
View view;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
if(savedInstanceState != null){
person = (Person)savedInstanceState.getSerializable("person");
}
view = inflater.inflate(R.layout.person_view, container, false);
icon = (ImageView)view.findViewById(R.id.icon);
text1 = (TextView)view.findViewById(R.id.name);
text2 = (TextView)view.findViewById(R.id.email);
text3 = (TextView)view.findViewById(R.id.info);
return view;
}
@Override
public void onStart() {
super.onStart();
Bundle args = getArguments();
if (args != null) {
person = (Person)args.getSerializable("context");
text1.setText(person.getName());
text2.setText(person.getEmail());
text3.setText("Quisque semper ultricies iaculis. Vestibulum nec metus adipiscing, egestas sem mattis, ornare nulla. Quisque nec nibh nec lacus euismod gravida. Proin at pretium enim. In auctor, nisi sit amet pharetra facilisis, est justo mattis mi, eget mattis tortor ligula non orci. Vestibulum neque augue, elementum vitae aliquam non, condimentum ac dui. Nullam ultricies velit nec diam aliquam, sed lacinia sem eleifend. Quisque quam sapien, sodales id suscipit nec, consequat vel nunc. Quisque eu velit nisi. Donec varius consequat metus, tempor semper tortor ultricies vel. Mauris eget arcu nisi. Proin sit amet dui nisl. Quisque auctor lobortis augue sit amet egestas. Fusce mattis aliquam ante, et bibendum nibh ullamcorper et. Integer ipsum nibh, placerat a felis ut, accumsan rutrum eros. Quisque lacinia facilisis ipsum sed commodo.");
icon.setImageResource(R.drawable.ic_launcher);
}else{
if(person==null){
person = new Person("Test Testowy", "Testowy@gmail.com");
}
updateArticleView(person);
}
}
@Override
public void onSaveInstanceState(Bundle outState){
super.onSaveInstanceState(outState);
outState.putSerializable("person", person);
}
public void updateArticleView(Person externalPerson) {
this.person = externalPerson;
text1.setText(externalPerson.getName());
text2.setText(externalPerson.getEmail());
text3.setText("Quisque semper ultricies iaculis. Vestibulum nec metus adipiscing, egestas sem mattis, ornare nulla. Quisque nec nibh nec lacus euismod gravida. Proin at pretium enim. In auctor, nisi sit amet pharetra facilisis, est justo mattis mi, eget mattis tortor ligula non orci. Vestibulum neque augue, elementum vitae aliquam non, condimentum ac dui. Nullam ultricies velit nec diam aliquam, sed lacinia sem eleifend. Quisque quam sapien, sodales id suscipit nec, consequat vel nunc. Quisque eu velit nisi. Donec varius consequat metus, tempor semper tortor ultricies vel. Mauris eget arcu nisi. Proin sit amet dui nisl. Quisque auctor lobortis augue sit amet egestas. Fusce mattis aliquam ante, et bibendum nibh ullamcorper et. Integer ipsum nibh, placerat a felis ut, accumsan rutrum eros. Quisque lacinia facilisis ipsum sed commodo.");
icon.setImageResource(R.drawable.ic_launcher);
}
}
および MainActivity:
public class MainActivity extends FragmentActivity implements OnHeadlineSelectedListener {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if(findViewById(R.id.fragment_container)!=null){
if (savedInstanceState != null) {
return;
}
getSupportFragmentManager().beginTransaction()
.add(R.id.fragment_container, new HeadlinesFragment()).commit();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public void onArticleSelected(Person person) {
PersonFragment fragment = (PersonFragment)getSupportFragmentManager().findFragmentById(R.id.person_view);
if(fragment!=null){
fragment.updateArticleView(person);
}else{
PersonFragment newFragment = new PersonFragment();
Bundle args = new Bundle();
args.putSerializable("context", person);
newFragment.setArguments(args);
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.fragment_container, newFragment);
transaction.addToBackStack(null);
transaction.commit();
}
}
}
問題: 最初はすべて問題ありませんが、(エミュレータ ctrl+f12 で) 方向モードを横向きに変更し、再び portin に戻ってリストビューからいくつかのものを選択すると、「残念ながらアプリケーションが停止しました」というメッセージが表示されます。
それはlogcatです：
11-02 14:29:03.396: E/AndroidRuntime(802): FATAL EXCEPTION: main
11-02 14:29:03.396: E/AndroidRuntime(802): java.lang.NullPointerException
11-02 14:29:03.396: E/AndroidRuntime(802): at com.example.friendslist.PersonFragment.updateArticleView(PersonFragment.java:68)
11-02 14:29:03.396: E/AndroidRuntime(802): at com.example.friendslist.MainActivity.onArticleSelected(MainActivity.java:43)
11-02 14:29:03.396: E/AndroidRuntime(802): at com.example.friendslist.HeadlinesFragment.onListItemClick(HeadlinesFragment.java:69)
11-02 14:29:03.396: E/AndroidRuntime(802): at android.support.v4.app.ListFragment$2.onItemClick(ListFragment.java:58)
11-02 14:29:03.396: E/AndroidRuntime(802): at android.widget.AdapterView.performItemClick(AdapterView.java:298)
11-02 14:29:03.396: E/AndroidRuntime(802): at android.widget.AbsListView.performItemClick(AbsListView.java:1100)
11-02 14:29:03.396: E/AndroidRuntime(802): at android.widget.AbsListView$PerformClick.run(AbsListView.java:2749)
11-02 14:29:03.396: E/AndroidRuntime(802): at android.widget.AbsListView$1.run(AbsListView.java:3423)
11-02 14:29:03.396: E/AndroidRuntime(802): at android.os.Handler.handleCallback(Handler.java:725)
11-02 14:29:03.396: E/AndroidRuntime(802): at android.os.Handler.dispatchMessage(Handler.java:92)
11-02 14:29:03.396: E/AndroidRuntime(802): at android.os.Looper.loop(Looper.java:137)
11-02 14:29:03.396: E/AndroidRuntime(802): at android.app.ActivityThread.main(ActivityThread.java:5041)
11-02 14:29:03.396: E/AndroidRuntime(802): at java.lang.reflect.Method.invokeNative(Native Method)
11-02 14:29:03.396: E/AndroidRuntime(802): at java.lang.reflect.Method.invoke(Method.java:511)
11-02 14:29:03.396: E/AndroidRuntime(802): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
11-02 14:29:03.396: E/AndroidRuntime(802): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
11-02 14:29:03.396: E/AndroidRuntime(802): at dalvik.system.NativeStart.main(Native Method)
私の主な問題は、「原因」のようなものを常に探していることです。ここではそれがありませんでした。誰かがどこに問題があるか教えてもらえますか?
PS通常のAndroidの例では、サブフォルダーの名前をlayout-largeからlayout-landに変更すると、同じ問題が発生します。
アクティビティ：
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/fragment_container"
android:layout_width="match_parent"
android:layout_height="match_parent" />
person_view:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
android:layout_marginRight="10dp"
android:layout_marginLeft="10dp" >
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal">
<ImageView
android:id="@+id/icon"
android:layout_width="72dp"
android:layout_height="74dp"
android:src="@drawable/ic_launcher" />
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="match_parent" >
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:orientation="vertical" >
<TextView
android:id="@+id/name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Imie i nazwisko" />
<TextView
android:id="@+id/email"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="email@sample.com" />
</LinearLayout>
</LinearLayout>
</LinearLayout>
<TextView
android:id="@+id/info"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:text="info" />
land サブフォルダーでの主なアクティビティ:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="match_parent">
<fragment android:name="com.example.friendslist.HeadlinesFragment"
android:id="@+id/headlines_fragment"
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="match_parent" />
<fragment android:name="com.example.friendslist.PersonFragment"
android:id="@+id/person_view"
android:layout_weight="2"
android:layout_width="0dp"
android:layout_height="match_parent" />