我正在制作我的第一个安卓应用程序。
我目前正在尝试让自定义适配器工作。
这是代码:
自定义适配器类:
class CustomListAdapter extends BaseAdapter {
Context mContext;
// List <Note> notesR = new ArrayList<Note>();
ArrayList<Note> notesR;
public CustomListAdapter (List notes) {
// mContext = context;
// notesR = = notes;
notesR = new ArrayList<Note>(3);
notesR.add(new Note("Hello", "bye", new Date()));
notesR.add(new Note("Hello", "bye", new Date()));
notesR.add(new Note("Hello", "bye", new Date()));
}
@Override
public int getCount() {
return notesR.size();
}
@Override
public Object getItem(int i) {
return notesR.get(i);
}
@Override
public long getItemId(int i) {
return i;
}
// This method is called to draw each row of the list
@Override
public View getView(int index, View convertView, final ViewGroup parent) {
View vi = convertView;
if (vi == null) {
LayoutInflater inflater;
inflater = LayoutInflater.from(parent.getContext());
vi = inflater.inflate(R.layout.item_list, parent, false);
}
final Note noteModel = notesR.get(index);
TextView date = (TextView) vi.findViewById(R.id.date);
date.setText("" + noteModel.getDate());
TextView title = (TextView) vi.findViewById(R.id.title);
title.setText(noteModel.getTitle());
TextView content = (TextView) vi.findViewById(R.id.content);
content.setText(noteModel.getNote());
// here you inflate the layout you want for the row
final View view = View.inflate(mContext, R.layout.item_list, null);
return view;
list 笔记类:
public class ListNotesActivity extends Activity {
@Override
public boolean onContextItemSelected(MenuItem item) {
AdapterView.AdapterContextMenuInfo info = (AdapterView.AdapterContextMenuInfo)item.getMenuInfo();
notes.remove(info.position);
populateList();
return true;
}
@Override
public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) {
super.onCreateContextMenu(menu, v, menuInfo);
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.context_menu, menu);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (resultCode == RESULT_CANCELED){
return;
}
Serializable extra = data.getSerializableExtra("Note");
if (extra != null){
Note newNote = (Note)extra;
if (editingNoteId > -1){
notes.set(editingNoteId, newNote);
editingNoteId = -1;
}
else {
notes.add(newNote);
};
populateList();
}
}
private List<Note> notes = new ArrayList<Note>();
private ListView notesListView;
private int editingNoteId = -1;
@Override
protected void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_list_notes);
notesListView = (ListView)findViewById(R.id.notesListView);
notesListView.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapter, View view, int itemNumber, long id) {
Intent editNoteIntent = new Intent(view.getContext(), EditNotesActivity.class);
editNoteIntent.putExtra("Note", notes.get(itemNumber));
editingNoteId = itemNumber;
startActivityForResult(editNoteIntent, 1);
}
});
registerForContextMenu(notesListView);
notes.add(new Note("1 Note", "blah blah", new Date()));
notes.add(new Note("2 Note", "blah blah", new Date()));
notes.add(new Note("3 Note", "blah blah", new Date()));
notes.add(new Note("4 Note", "blah blah", new Date()));
notes.add(new Note("5 Note", "blah blah", new Date()));
notes.add(new Note("6 Note", "blah blah", new Date()));
notes.add(new Note("7 Note", "blah blah", new Date()));
notes.add(new Note("8 Note", "blah blah", new Date()));
populateList();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.list_notes, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
//notes.add(new Note("Added note", "blah", new Date()));
//populateList();
Intent editNoteIntent = new Intent (this, EditNotesActivity.class);
startActivityForResult(editNoteIntent, 1);
return true;
}
// Populate Method
// Populate Method
private void populateList() {
CustomListAdapter customAdapter = new CustomListAdapter(notes);
notesListView.setAdapter(customAdapter);
//CustomAdapter customAdapter = new CustomAdapter();
//notesListView.setAdapter(customAdapter);
我一直试图让 apapter 开始使用虚拟数据，但它仍然不断崩溃。
我一直试图找到断点问题的根源，
如果我在第一个@Override 之前放了一个吱吱声点，它会一直运行到那里，但是一旦我让它运行到@Override，它就会崩溃。
我尝试删除第一个覆盖，然后代码运行良好，直到下一个覆盖，它再次崩溃。
我整天都在努力让这个工作，我什至把它发给了我更远的 C# 开发人员，他也不知道。
如果有人能告诉我究竟是什么原因造成的，我将不胜感激。
我下载了一个示例，它使用与我的非常相似的代码，并且运行良好。这是示例中的代码:
public class CustomAdapter extends BaseAdapter {
private static final String TAG = CustomAdapter.class.getSimpleName();
ArrayList<DataModel> listArray;
public CustomAdapter() {
listArray = new ArrayList<DataModel>(5);
listArray.add(new DataModel("Title1", "Java", new Date()));
listArray.add(new DataModel("name2", "Python", new Date()));
listArray.add(new DataModel("name3", "Django", new Date()));
listArray.add(new DataModel("name4", "Groovy", new Date()));
listArray.add(new DataModel("name5", "Maven", new Date()));
}
@Override
public int getCount() {
return listArray.size(); // total number of elements in the list
}
@Override
public Object getItem(int i) {
return listArray.get(i); // single item in the list
}
@Override
public long getItemId(int i) {
return i; // index number
}
@Override
public View getView(int index, View view, final ViewGroup parent) {
if (view == null) {
LayoutInflater inflater = LayoutInflater.from(parent.getContext());
view = inflater.inflate(R.layout.single_list_item, parent, false);
}
final DataModel dataModel = listArray.get(index);
TextView title = (TextView) view.findViewById(R.id.title);
title.setText(dataModel.getTitle());
TextView content = (TextView) view.findViewById(R.id.content);
content.setText(dataModel.getContent());
TextView date = (TextView) view.findViewById(R.id.date);
date.setText("" + dataModel.getDate());
return view;
编辑1:
LogCat (i filtered it for just my app):
06-12 15:26:46.359 8851-8851/com.fishingfon.notetakerui
D/dalvikvm: Late-enabling CheckJNI 06-12 15:26:46.399
8851-8851/com.fishingfon.notetakerui W/ActivityThread: Application com.fishingfon.notetakerui is waiting for the debugger on port 8100... 06-12 15:26:46.409 8851-8851/com.fishingfon.notetakerui
I/System.out: Sending WAIT chunk 06-12 15:26:46.419
8851-8856/com.fishingfon.notetakerui I/dalvikvm: Debugger is active 06-12 15:26:46.614 8851-8851/com.fishingfon.notetakerui
I/System.out: Debugger has connected 06-12 15:26:46.614
8851-8851/com.fishingfon.notetakerui I/System.out: waiting for debugger to settle... 06-12 15:26:46.814
8851-8851/com.fishingfon.notetakerui I/System.out: waiting for debugger to settle... 06-12 15:26:47.014
8851-8851/com.fishingfon.notetakerui I/System.out: waiting for debugger to settle... 06-12 15:26:47.214
8851-8851/com.fishingfon.notetakerui I/System.out: waiting for debugger to settle... 06-12 15:26:47.289
2137-2137/com.google.android.youtube D/YouTube MDX: Recieved intent android.intent.action.SCREEN_OFF 06-12 15:26:47.414
8851-8851/com.fishingfon.notetakerui I/System.out: waiting for debugger to settle... 06-12 15:26:47.614
8851-8851/com.fishingfon.notetakerui I/System.out: waiting for debugger to settle... 06-12 15:26:47.814
8851-8851/com.fishingfon.notetakerui I/System.out: debugger has settled (1315) 06-12 15:26:48.149
8851-8851/com.fishingfon.notetakerui D/AndroidRuntime: Shutting down VM 06-12 15:26:48.149 8851-8851/com.fishingfon.notetakerui
W/dalvikvm: threadid=1: thread exiting with uncaught exception (group=0x40f4d930) 06-12 15:26:48.169
8851-8851/com.fishingfon.notetakerui E/AndroidRuntime: FATAL EXCEPTION: main java.lang.RuntimeException: Unable to start activity ComponentInfo{com.fishingfon.notetakerui/com.fishingfon.notetakerui.ListNotesActivity}: java.lang.NullPointerException at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2307) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2357) at android.app.ActivityThread.access$600(ActivityThread.java:153) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1247) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loop(Looper.java:137) at android.app.ActivityThread.main(ActivityThread.java:5231) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:511) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:795) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:562) at dalvik.system.NativeStart.main(Native Method) Caused by: java.lang.NullPointerException at com.fishingfon.notetakerui.ListNotesActivity.populateList(ListNotesActivity.java:145) at com.fishingfon.notetakerui.ListNotesActivity.onCreate(ListNotesActivity.java:110) at android.app.Activity.performCreate(Activity.java:5110) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2261) ... 11 more 06-12 15:26:48.209 8851-8851/com.fishingfon.notetakerui I/Process: Sending signal. PID: 8851 SIG: 9
编辑2:
新适配器代码:
class CustomListAdapter extends BaseAdapter {
Context mContext;
// List <Note> notesR = new ArrayList<Note>();
ArrayList<Note> notesR;
public CustomListAdapter (Context context, Object notes) {
mContext = context;
// notesR = = notes;
notesR = new ArrayList<Note>(3);
notesR.add(new Note("Hello", "bye", new Date()));
notesR.add(new Note("Hello", "bye", new Date()));
notesR.add(new Note("Hello", "bye", new Date()));
}
@Override
public int getCount() {
return notesR.size();
}
@Override
public Object getItem(int position) {
return notesR.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
// This method is called to draw each row of the list
@Override
public View getView(int position, View convertView, final ViewGroup parent) {
View vi = convertView;
if (vi == null) {
LayoutInflater inflater;
// inflater = LayoutInflater.from(parent.getContext());
vi = View.inflate(mContext, R.layout.item_list, null);
}
final Note noteModel = notesR.get(position);
TextView date = (TextView) vi.findViewById(R.id.date);
date.setText("" + noteModel.getDate());
TextView title = (TextView) vi.findViewById(R.id.title);
title.setText(noteModel.getTitle());
TextView content = (TextView) vi.findViewById(R.id.content);
content.setText(noteModel.getNote());
return vi;
提前致谢
干杯
科里
最佳答案
这里不需要此代码
final View view = View.inflate(mContext, R.layout.item_list, null);
return view;
只需添加这个而不是上面
return vi;
在 CustomListAdapter 的 getView() 中
编辑
public CustomListAdapter (Context context, int id, ArrayList<Note> notes) {
super(context,id,notes);
mContext = context;
notesR = = notes;
}
在 Activity 中
CustomListAdapter customAdapter = new CustomListAdapter(this, R.layout.listitem, notes);
notesListView.setAdapter(customAdapter);
关于java - 应用程序在@Override 点不断崩溃，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/17057874/