我正在创建一个列表视图，该视图由Sqlite数据库填充（由我的＆＃34; DBAdapter＆＃34;类创建）。我正在构建的这个日志以包含listView的片段开始，该片段打开一个活动（＆＃34; TrainingLogCreate.java＆＃34;通过添加按钮），向用户显示两个editText框（一个当前未使用）。当我回到片段时，数据被写入sqlite数据库，但是在我返回导航抽屉并选择日志之前，新数据不会出现，日志会重新加载片段然后在列表中显示新信息视图。无论如何，当活动解散并且片段恢复时，我可以重新填充listView吗？
将对DBAdapter：
package com.hardingsoftware.hrcfitness;
/**
* Created by John on 2/9/16.
*/
public class DBAdapter {
//COLUMNS
static final String ROWID="id";
static final String NAME = "name";
static final String POSITION = "position";
//DB PROPERTIES
static final String DBNAME="m_DB";
static final String TBNAME="m_TB";
static final int DBVERSION='1';
static final String CREATE_TB="CREATE TABLE m_TB(id INTEGER PRIMARY KEY AUTOINCREMENT,"
+ "name TEXT NOT NULL,position TEXT NOT NULL);";
final Context c;
SQLiteDatabase db;
DBHelper helper;
public DBAdapter(FragmentActivity ctx) {
// TODO Auto-generated constructor stub
this.c=ctx;
helper=new DBHelper(c);
}
// INNER HELPER DB CLASS
private static class DBHelper extends SQLiteOpenHelper
{
public DBHelper(Context context ) {
super(context, DBNAME, null, DBVERSION);
// TODO Auto-generated constructor stub
}
@Override
public void onCreate(SQLiteDatabase db) {
try
{
db.execSQL(CREATE_TB);
} catch (SQLException e) {
e.printStackTrace();
}
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
Log.w("DBAdapetr","Upgrading DB");
db.execSQL("DROP TABLE IF EXISTS m_TB");
onCreate(db);
}
}
// OPEN THE DB
public DBAdapter openDB()
{
try
{
db=helper.getWritableDatabase();
}catch(SQLException e)
{
Toast.makeText(c, e.getMessage(), Toast.LENGTH_LONG).show();
}
return this;
}
//CLOSE THE DB
public void close()
{
helper.close();
}
//INSERT INTO TABLE
public long add(String name,String pos)
{
try
{
ContentValues cv=new ContentValues();
cv.put(NAME, name);
cv.put(POSITION, pos);
return db.insert(TBNAME, ROWID, cv);
}catch(SQLException e)
{
e.printStackTrace();
}
return 0;
}
//GET ALL VALUES
public Cursor getAllNames()
{
String[] columns={ROWID,NAME,POSITION};
return db.query(TBNAME, columns, null, null, null, null, null);
}
}
培训日志：
package com.hardingsoftware.hrcfitness;
/**
* Created by John on 2/3/16.
*/
public class TrainingLog extends Fragment {
ListView lv;
ArrayList<String> players = new ArrayList<String>();
ArrayAdapter<String> adapter;
ArrayAdapter<String> clearAdapter;
public TrainingLog() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View rootView = inflater.inflate(R.layout.fragment_training_log, container, false);
lv = (ListView) rootView.findViewById(R.id.myListView);
final DBAdapter db = new DBAdapter(this.getActivity());
setHasOptionsMenu(true);
players.clear();
//OPEN
db.openDB();
//RETRIEVE
Cursor c=db.getAllNames();
while(c.moveToNext())
{
String name=c.getString(1);
players.add(name);
}
db.close();
adapter=new ArrayAdapter<String>(this.getActivity(),android.R.layout.simple_selectable_list_item,players);
lv.setAdapter(adapter);
/* ListAdapter myTrainingAdapter = new TrainingAdapter(this.getActivity(), exercizeActivity, exercizeDetail);
ListView myListView = (ListView) rootView.findViewById(R.id.myListView);
myListView.setAdapter(myTrainingAdapter); */
return rootView;
}
@Override
public void onResume() {
super.onResume();
final DBAdapter db = new DBAdapter(this.getActivity());
/* //OPEN
db.openDB();
getContext().deleteDatabase("db");
//RETRIEVE
Cursor c=db.getAllNames();
while(c.moveToNext())
{
String name=c.getString(1);
players.add(name);
}
db.close();
lv.setAdapter(clearAdapter);
adapter=new ArrayAdapter<String>(this.getActivity(),android.R.layout.simple_selectable_list_item,players);
lv.setAdapter(adapter); */
}
@Override
public void onCreateOptionsMenu(
Menu menu, MenuInflater inflater) {
inflater.inflate(R.menu.traning_menu_itemdetail, menu);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// handle item selection
switch (item.getItemId()) {
case R.id.action_add:
Intent trainingCreateIntent = new Intent (getContext(), TrainingLogCreate.class);
startActivity(trainingCreateIntent);
return true;
default:
return super.onOptionsItemSelected(item);
}
}
}
TrainingLogCreate：
package com.hardingsoftware.hrcfitness;
/**
* Created by John on 2/6/16.
*/
public class TrainingLogCreate extends AppCompatActivity {
EditText nameTxt;
EditText posTxt;
Button savebtn;
Context context = this;
public TrainingLogCreate() {
// Required empty public constructor
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.training_log_create);
savebtn = (Button) findViewById(R.id.saveButton);
nameTxt = (EditText) findViewById(R.id.exercizeActivity);
posTxt = (EditText) findViewById(R.id.exercizeDetails);
final DBAdapter db=new DBAdapter(this);
savebtn.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
//OPEN
db.openDB();
//INSERT
long result=db.add(nameTxt.getText().toString(), posTxt.getText().toString());
if(result > 0)
{
nameTxt.setText("");
posTxt.setText("");
}else
{
Toast.makeText(getApplicationContext(), "Failure", Toast.LENGTH_SHORT).show();
}
//CLOSE DB
db.close();
//Close Fragment
finish();
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater mif = getMenuInflater();
mif.inflate(R.menu.training_create_menu, menu);
getActionBar().show();
return super.onCreateOptionsMenu(menu);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// handle item selection
switch (item.getItemId()) {
case R.id.action_save:
//add save functionality
return true;
default:
return super.onOptionsItemSelected(item);
}
}
}
答案 0 :(得分：0)
从BaseAdapter或CusrsorAdapter实现DBAdapter。每当在DB中更新数据时，都会根据您的实现调用dataSetChanged或SwapeCursor。
请参阅以下链接以了解实施情况。