我会直奔主题。我有 1 个班级，其中有 6 个按钮。每个按钮都会将一些参数保存到 SQLiteDatabase ，然后它会启动一个 Activity。
新的 Activity 接受参数并查询数据库以相应地提取数据。当活动启动时，如果我按下另一个或相同的按钮，我会清除参数以便再次保存它们。
如果 1 个表（链接到按钮）为空，则返回我想要的消息。问题是如果 1 为空，那么所有表都会返回消息，即使它们有数据！
我的第一堂课
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();
}});
}
}
第二个类，如您所见，它从 SQLite 数据库中提取数据（您还可以看到空结果的消息“此处未添加任何内容。转到站点添加更多内容。”）
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;
}
}
编辑
另外，我忘了提到如果我将验证条件设置为 cur2 == null 应用程序会崩溃，因为光标超出范围（for 循环触发）