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我會直接指向這一點。我有一個班，我有6個按鈕。每個按鈕保存到SQLite數據庫一些參數然後它啓動一個活動。ListView，遊標和空集
新活動取參數並查詢數據庫以相應地提取數據。當活動啓動時，我清除參數爲了再次保存它們，如果我按另一個或相同的按鈕。
如果1個表（鏈接到按鈕）爲空，它會返回我想要的消息。問題是如果1是空的，那麼即使他們有數據，所有的表也會返回消息！
我一等
public class HRecords extends Activity {
SQLiteDatabase myDB=null;
Button tes,con,al,me,pr,va;
protected void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.records);
tes=(Button) findViewById(R.id.testbut);
con=(Button) findViewById(R.id.condbut);
al=(Button) findViewById(R.id.albut);
me=(Button) findViewById(R.id.medbut);
pr=(Button) findViewById(R.id.procbut);
va=(Button) findViewById(R.id.vacbut);
Database openHelper = new Database(this);//create new Database to take advantage of the SQLiteOpenHelper class
myDB = openHelper.getWritableDatabase(); // or getWritableDatabase();
myDB=SQLiteDatabase.openDatabase("data/data/com.example.login2/databases/aeglea", null, SQLiteDatabase.OPEN_READWRITE);//set myDB to aeglea
doclicks();
}
private void doclicks(){
tes.setOnClickListener(new View.OnClickListener() {
public void onClick(View arg0) {
ContentValues values = new ContentValues();
values.put("ton", "Tests");
values.put("tazle","user_test");
myDB.insert("history_go",null, values);
//create new intent
Intent record = new Intent(getApplicationContext(), Record.class);
// Close all views before launching logged
record.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(record);
// Close Login Screen
onPause();
}});
con.setOnClickListener(new View.OnClickListener() {
public void onClick(View arg0) {
ContentValues values = new ContentValues();
values.put("ton", "Medical Conditions");
values.put("tazle","user_cond");
myDB.insert("history_go",null, values);
//create new intent
Intent record = new Intent(getApplicationContext(), Record.class);
// Close all views before launching logged
record.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(record);
// Close Login Screen
onPause();
}});
al.setOnClickListener(new View.OnClickListener() {
public void onClick(View arg0) {
ContentValues values = new ContentValues();
values.put("ton", "Allergies");
values.put("tazle","user_all");
myDB.insert("history_go",null, values);
//create new intent
Intent record = new Intent(getApplicationContext(), Record.class);
// Close all views before launching logged
record.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(record);
// Close Login Screen
onPause();
}});
me.setOnClickListener(new View.OnClickListener() {
public void onClick(View arg0) {
ContentValues values = new ContentValues();
values.put("ton", "Medication");
values.put("tazle","user_med");
myDB.insert("history_go",null, values);
//create new intent
Intent record = new Intent(getApplicationContext(), Record.class);
// Close all views before launching logged
record.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(record);
// Close Login Screen
onPause();
}});
pr.setOnClickListener(new View.OnClickListener() {
public void onClick(View arg0) {
ContentValues values = new ContentValues();
values.put("ton", "Medical Procedures");
values.put("tazle","user_proc");
myDB.insert("history_go",null, values);
//create new intent
Intent record = new Intent(getApplicationContext(), Record.class);
// Close all views before launching logged
record.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(record);
// Close Login Screen
onPause();
}});
va.setOnClickListener(new View.OnClickListener() {
public void onClick(View arg0) {
ContentValues values = new ContentValues();
values.put("ton", "Vaccinations");
values.put("tazle","user_vacc");
myDB.insert("history_go",null, values);
//create new intent
Intent record = new Intent(getApplicationContext(), Record.class);
// Close all views before launching logged
record.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(record);
// Close Login Screen
onPause();
}});
}
}
正如你可以看到它就會從SQLite數據庫的數據（你也可以看到空的結果的消息第二類「這裏沒有什麼增加。進入網站添加更多。「）
public class Record extends Activity{
SQLiteDatabase myDB=null;
TextView title=null;
Cursor cur,cur2=null;
ListView list=null;
private ArrayAdapter<String> listAdapter ;
protected void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.record);
title = (TextView) findViewById(R.id.recordTitle);
list = (ListView) findViewById(R.id.listView1);
Database openHelper = new Database(this);
myDB = openHelper.getReadableDatabase();
myDB=SQLiteDatabase.openDatabase("data/data/com.example.login2/databases/aeglea", null, SQLiteDatabase.OPEN_READONLY);
Database db = new Database(getApplicationContext());
cur = fetchOption("SELECT * FROM history_go");
title.setText(cur.getString(cur.getColumnIndex("ton")));
ArrayList<String> itemlist = new ArrayList<String>();
String[] names=null;
//do query
cur2=fetchOption("SELECT * FROM "+cur.getString(cur.getColumnIndex("tazle")));
//check for results
if (cur2.getCount()==0) {
names = new String[] { "Nothing Added here. Go to the site to add more."};
}else{
names = new String[] {cur2.getString(cur2.getColumnIndex("name"))};
}
//add the array as list to the ArrayList
itemlist.addAll(Arrays.asList(names));
listAdapter = new ArrayAdapter<String>(this, R.layout.item, itemlist);
//if results add the rest
if(cur2.getCount()!=0){
for(int i=0;i<(cur2.getCount()-1);i++){
cur2.moveToNext();
listAdapter.add(cur2.getString(cur2.getColumnIndex("name")));
}
}
// Set the ArrayAdapter as the ListView's adapter.
list.setAdapter(listAdapter);
//remove the navigation history
db.resetHistoryNavigation();
cur.close();
cur2.close();
}
public Cursor fetchOption(String query) throws SQLException {
Cursor mCursor = myDB.rawQuery(query, null);
if (mCursor != null) {
mCursor.moveToFirst();
}
return mCursor;
}
}
編輯
另外，我忘了提，如果我設置的驗證條件CUR2 == null由於光標超出邊界（for循環觸發），應用程序會崩潰