我正在学习关于Sherlock ActionBar的开发，我使用Sherlock ActionBar创建了一个示例程序，用于将日期从数据库填充到列表视图。
因为我在一个活动中创建了两个选项卡，我用于输入详细信息的第一个选项卡（fragment1）工作正常，但需要将数据填充到列表视图中的第二个选项卡（fragment2）不起作用细
请查看我的代码：
Fragment2.java
public class Fragment2 extends SherlockFragment implements TabListener {
private Fragment mFragment;
DBAdapter db;
Cursor c;
ListView list;
MyAdapter myAdapter;
View view ;
Context context;
@Override
public void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
//getActivity().setContentView(R.layout.details_listview);
db = new DBAdapter(getActivity());
db.openDatabase();
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// TODO Auto-generated method stub
view = inflater.inflate(R.layout.details_listview, null);
return view;
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onActivityCreated(savedInstanceState);
list = (ListView)view.findViewById(R.id.listView1);
registerForContextMenu(list);
updateListView();
}
private void updateListView() {
// TODO Auto-generated method stub
c = db.getAllRecords();
myAdapter = new MyAdapter();
list.setAdapter(myAdapter);
}
@Override
public void onTabSelected(Tab tab, FragmentTransaction ft) {
// TODO Auto-generated method stub
mFragment = new Fragment2();
ft.add(android.R.id.content, mFragment);
ft.attach(mFragment);
}
@Override
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
// TODO Auto-generated method stub
ft.remove(mFragment);
}
@Override
public void onTabReselected(Tab tab, FragmentTransaction ft) {
// TODO Auto-generated method stub
}
class MyAdapter extends BaseAdapter{
Context context;
@Override
public int getCount() {
// TODO Auto-generated method stub
return c.getCount();
}
@Override
public Object getItem(int arg0) {
// TODO Auto-generated method stub
return null;
}
@Override
public long getItemId(int arg0) {
// TODO Auto-generated method stub
return 0;
}
@Override
public android.view.View getView(int position, android.view.View conview,
ViewGroup arg2) {
LayoutInflater inflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
conview = inflater.inflate(R.layout.customllistview, null);
TextView t1 = (TextView)conview.findViewById(R.id.idtextView);
TextView t2 = (TextView)conview.findViewById(R.id.nametextView);
TextView t3 = (TextView)conview.findViewById(R.id.locationtextView);
c.moveToPosition(position);
String id = c.getString(0);
String name = c.getString(1);
String location = c.getString(2);
t1.setText("row id: "+id);
t2.setText("name :"+name);
t3.setText("location :"+location);
return conview;
}
}
}
数据库数据库适配器： DBAdapter.java
public class DBAdapter {
DBHelper dbHelper;
Context context;
SQLiteDatabase db;
public static final int DATABASE_VERSION = 1;
String DATABASE_NAME = "sampleDB";
String TABLE_NAME = "sample";
String COL_ROWID = "rowid";
String COL_NAME ="name";
String COL_LOCATION = "location";
String CREATE_TABLE = "create table sample(rowid integer primary key autoincrement,name text not null,location text not null) ";
public DBAdapter(Context c) {
// TODO Auto-generated constructor stub
this.context = c;
dbHelper = new DBHelper(context);
}
DBAdapter openDatabase() {
db = dbHelper.getWritableDatabase();
return this;
}
void close() {
dbHelper.close();
}
long insertRecord(String name, String location) {
ContentValues con = new ContentValues();
con.put(COL_NAME, name);
con.put(COL_LOCATION, location);
return db.insert(TABLE_NAME, null, con);
}
Cursor getAllRecords(){
String[] columns = {COL_ROWID,COL_NAME,COL_LOCATION};
return db.query(TABLE_NAME, columns, null, null, null, null, null);
}
class DBHelper extends SQLiteOpenHelper {
public DBHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
// TODO Auto-generated constructor stub
}
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
db.execSQL(CREATE_TABLE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
}
}
}
最后这是我的logcat输出：
07-22 18:54:16.684: E/AndroidRuntime(1204): FATAL EXCEPTION: main
07-22 18:54:16.684: E/AndroidRuntime(1204): java.lang.NullPointerException
07-22 18:54:16.684: E/AndroidRuntime(1204): at com.example.sherlocklistview.Fragment2$MyAdapter.getView(Fragment2.java:111)
07-22 18:54:16.684: E/AndroidRuntime(1204): at android.widget.AbsListView.obtainView(AbsListView.java:1430)
07-22 18:54:16.684: E/AndroidRuntime(1204): at android.widget.ListView.measureHeightOfChildren(ListView.java:1216)
07-22 18:54:16.684: E/AndroidRuntime(1204): at android.widget.ListView.onMeasure(ListView.java:1127)
07-22 18:54:16.684: E/AndroidRuntime(1204): at android.view.View.measure(View.java:8313)
07-22 18:54:16.684: E/AndroidRuntime(1204): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3138)
07-22 18:54:16.684: E/AndroidRuntime(1204): at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1017)
07-22 18:54:16.684: E/AndroidRuntime(1204): at android.widget.LinearLayout.measureHorizontal(LinearLayout.java:701)
07-22 18:54:16.684: E/AndroidRuntime(1204): at android.widget.LinearLayout.onMeasure(LinearLayout.java:311)
07-22 18:54:16.684: E/AndroidRuntime(1204): at android.view.View.measure(View.java:8313)
07-22 18:54:16.684: E/AndroidRuntime(1204): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3138)
07-22 18:54:16.684: E/AndroidRuntime(1204): at android.widget.FrameLayout.onMeasure(FrameLayout.java:250)
07-22 18:54:16.684: E/AndroidRuntime(1204): at android.view.View.measure(View.java:8313)
07-22 18:54:16.684: E/AndroidRuntime(1204): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3138)
07-22 18:54:16.684: E/AndroidRuntime(1204): at android.widget.FrameLayout.onMeasure(FrameLayout.java:250)
07-22 18:54:16.684: E/AndroidRuntime(1204): at android.view.View.measure(View.java:8313)
07-22 18:54:16.684: E/AndroidRuntime(1204): at android.widget.LinearLayout.measureVertical(LinearLayout.java:531)
07-22 18:54:16.684: E/AndroidRuntime(1204): at android.widget.LinearLayout.onMeasure(LinearLayout.java:309)
07-22 18:54:16.684: E/AndroidRuntime(1204): at android.view.View.measure(View.java:8313)
07-22 18:54:16.684: E/AndroidRuntime(1204): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3138)
07-22 18:54:16.684: E/AndroidRuntime(1204): at android.widget.FrameLayout.onMeasure(FrameLayout.java:250)
07-22 18:54:16.684: E/AndroidRuntime(1204): at android.view.View.measure(View.java:8313)
07-22 18:54:16.684: E/AndroidRuntime(1204): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3138)
07-22 18:54:16.684: E/AndroidRuntime(1204): at android.widget.FrameLayout.onMeasure(FrameLayout.java:250)
07-22 18:54:16.684: E/AndroidRuntime(1204): at android.view.View.measure(View.java:8313)
07-22 18:54:16.684: E/AndroidRuntime(1204): at android.view.ViewRoot.performTraversals(ViewRoot.java:839)
07-22 18:54:16.684: E/AndroidRuntime(1204): at android.view.ViewRoot.handleMessage(ViewRoot.java:1859)
07-22 18:54:16.684: E/AndroidRuntime(1204): at android.os.Handler.dispatchMessage(Handler.java:99)
07-22 18:54:16.684: E/AndroidRuntime(1204): at android.os.Looper.loop(Looper.java:123)
07-22 18:54:16.684: E/AndroidRuntime(1204): at android.app.ActivityThread.main(ActivityThread.java:3683)
07-22 18:54:16.684: E/AndroidRuntime(1204): at java.lang.reflect.Method.invokeNative(Native Method)
07-22 18:54:16.684: E/AndroidRuntime(1204): at java.lang.reflect.Method.invoke(Method.java:507)
07-22 18:54:16.684: E/AndroidRuntime(1204): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
07-22 18:54:16.684: E/AndroidRuntime(1204): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
07-22 18:54:16.684: E/AndroidRuntime(1204): at dalvik.system.NativeStart.main(Native Method)
请为我的问题提供一些解决方案
答案 0 :(得分：0)
请提供有关哪条线正好是文件Fragment2.java中的111行的信息（考虑到导入行号）。
检查Fragment2.java中MyAdapter中的上下文变量，因为它看起来没有在任何地方初始化。