（可能是ArrayaAdapter）//'；java.lang.String java.lang.Object.toString（）'；关于空对象引用
我是一个初学者，也是我的第一个应用程序。我正在尝试做一个待办事项列表应用程序。现在，我卡住了，找不到我的错误。谁能帮我一下吗 已编辑 asilajandaActivity.java（可能是ArrayaAdapter）//'；java.lang.String java.lang.Object.toString（）'；关于空对象引用,java,android,android-arrayadapter,Java,Android,Android Arrayadapter,我是一个初学者，也是我的第一个应用程序。我正在尝试做一个待办事项列表应用程序。现在，我卡住了，找不到我的错误。谁能帮我一下吗 已编辑 asilajandaActivity.java public class asilajandaActivity extends AppCompatActivity { private TaskDbHelper mHelper; private ListView mTaskListView; private ArrayAdapter<String> mA
public class asilajandaActivity extends AppCompatActivity {
private TaskDbHelper mHelper;
private ListView mTaskListView;
private ArrayAdapter<String> mAdapter;
private ArrayAdapter<String> mAdapter2;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setTitle(R.string.title_activity_asilajanda);
setContentView(R.layout.activity_asilajanda);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
mHelper = new TaskDbHelper(this);
mTaskListView = (ListView) findViewById(R.id.list_todo);
updateUI();updateUI2();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main_menu, menu);
return super.onCreateOptionsMenu(menu);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.action_add_task:
final Dialog dialog= new Dialog(this);
dialog.setContentView(R.layout.dialod_ajanda);
dialog.setTitle("Etkinlik Ekle");
final EditText dateEditText=(EditText)dialog.findViewById(R.id.editText);
final EditText taskEditText =(EditText)dialog.findViewById(R.id.Text);
Button kaydet= (Button) dialog.findViewById(R.id.button4);
Button vazgec=(Button) dialog.findViewById(R.id.button5);
kaydet.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
try {
SQLiteDatabase db= mHelper.getWritableDatabase();
ContentValues values1 = new ContentValues();
String date = String.valueOf(dateEditText.getText());
values1.put(TaskContract.TaskEntry.COL_TASK_tar, date);
db.insertWithOnConflict(TaskContract.TaskEntry.TABLE, null, values1, SQLiteDatabase.CONFLICT_REPLACE);
} catch (Exception e) {
e.printStackTrace();
}
try {
SQLiteDatabase db= mHelper.getWritableDatabase();
ContentValues values = new ContentValues();
String date = String.valueOf(taskEditText.getText());
values.put(TaskContract.TaskEntry.COL_TASK_TITLE, date);
db.insertWithOnConflict(TaskContract.TaskEntry.TABLE, null, values, SQLiteDatabase.CONFLICT_REPLACE);
} catch (Exception e1) {
e1.printStackTrace();
}
db.close();
updateUI();updateUI2();
dialog.dismiss();
}
});
vazgec.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v){
dialog.dismiss();
}
});
dialog.create();
dialog.show();
return true;
default:
return super.onOptionsItemSelected(item);
}
}
public void deleteTask(View view) {
View parent = (View) view.getParent();
TextView taskTextView = (TextView) parent.findViewById(R.id.task_title);
TextView tarihtext =(TextView) parent.findViewById(R.id.tarih_text);
String task = String.valueOf(taskTextView.getText());
String date = String.valueOf(tarihtext.getText());
SQLiteDatabase db = mHelper.getWritableDatabase();
db.delete(TaskContract.TaskEntry.TABLE,
TaskContract.TaskEntry.COL_TASK_TITLE + " = ?",
new String[]{task});
db.delete(TaskContract.TaskEntry.TABLE,
TaskContract.TaskEntry.COL_TASK_tar,
new String[]{date});
db.close();
updateUI2();
updateUI();
}
private void updateUI() {
ArrayList<String> taskList = new ArrayList<>();
SQLiteDatabase db = mHelper.getReadableDatabase();
Cursor cursor = db.query(TaskContract.TaskEntry.TABLE,
new String[]{TaskContract.TaskEntry._ID, TaskContract.TaskEntry.COL_TASK_tar},
null, null, null, null, null);
while (cursor.moveToNext()) {
int idx1 = cursor.getColumnIndex(TaskContract.TaskEntry.COL_TASK_tar);
taskList.add(cursor.getString(idx1));
}
if (mAdapter == null) {
mAdapter = new ArrayAdapter<>(this,
R.layout.item_todo,
R.id.task_title,
taskList);
mTaskListView.setAdapter(mAdapter);
} else {
mAdapter.clear();
mAdapter.addAll(taskList);
mAdapter.notifyDataSetChanged();
}
cursor.close();
db.close();
}
private void updateUI2() {
ArrayList<String> dateList = new ArrayList<>();
SQLiteDatabase db = mHelper.getReadableDatabase();
Cursor cursor2 = db.query(TaskContract.TaskEntry.TABLE,
new String[]{TaskContract.TaskEntry._ID, TaskContract.TaskEntry.COL_TASK_TITLE},
null, null, null, null, null);
while (cursor2.moveToNext()) {
int idx = cursor2.getColumnIndex(TaskContract.TaskEntry.COL_TASK_TITLE);
dateList.add(cursor2.getString(idx));
}
if (mAdapter2 == null) {
mAdapter2 = new ArrayAdapter<>(this,
R.layout.item_todo,
R.id.task_title,
dateList);
mTaskListView.setAdapter(mAdapter2);
} else {
mAdapter2.clear();
mAdapter2.addAll(dateList);
mAdapter2.notifyDataSetChanged();
}
cursor2.close();
db.close();
}
07-28 04:04:16.722 25806-25806/com.lidenoapp.ajanda E/AndroidRuntime: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.Object.toString()' on a null object reference
try {
String date = String.valueOf(dateEditText.getText());
} catch (Exception e) {
e.printStackTrace();
}