[英]Android app is crashing when value searched doesn't exist in database
當我搜索數據庫中不存在的任何值時,應用程序立即崩潰。
public String ifExistIn(String stationName) {
String query = "SELECT stationName FROM review WHERE stationId" +
"='" + stationName + "' OR " + " stationName " + "='" + stationName + "' LIMIT 1";
try (SQLiteDatabase database = this.getWritableDatabase();
Cursor c = database.rawQuery(query, null)) {
c.moveToFirst();
return c.getString(c.getColumnIndex("stationName"));
}
}
Activity
將可用記錄添加到ListView
public View.OnClickListener searchStation = new View.OnClickListener() {
@Override
public void onClick(View v) {
String searchString = searchText.getText().toString();
//String useThis = dbHelper.ifExistIn(searchString);
if (list.contains(dbms.ifExistIn(searchString))) {
AlertDialog.Builder builder = new AlertDialog.Builder(SearchAndReview.this);
builder.setTitle("");
builder.setMessage("RECORD ALREADY IN THE LIST ");
builder.setNeutralButton("OK", null);
builder.create().show();
else {
list.add(dbms.ifExistIn(searchString));
listView.setAdapter(arrayAdapter);
}
}
}
};
Android Studio日志詳細信息致命異常
04-27 13:13:27.386 19845-19845/com.example.fahimghl.reviewapplication E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.fahimghl.reviewapplication, PID: 19845
android.database.CursorIndexOutOfBoundsException: Index 0 requested, with a size of 0
at android.database.AbstractCursor.checkPosition(AbstractCursor.java:426)
at android.database.AbstractWindowedCursor.checkPosition(AbstractWindowedCursor.java:136)
at android.database.AbstractWindowedCursor.getString(AbstractWindowedCursor.java:50)
at com.example.fahimghl.reviewapplication.DatabaseHelper.ifExistIn(DatabaseHelper.java:130)
at com.example.fahimghl.reviewapplication.SearchAndReview$10.onClick(SearchAndReview.java:172)
at android.view.View.performClick(View.java:4761)
at android.view.View$PerformClick.run(View.java:19767)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5312)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:901)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:696)
當我搜索數據庫應用程序中不存在的任何值時,都會立即崩潰。
然后可能您正在查詢一個空的游標。
try (SQLiteDatabase database = this.getWritableDatabase();
Cursor c = database.rawQuery(query, null)) {
if (c != null && c.moveToFirst()) {
return c.getString(c.getColumnIndex("stationName"));
}
}
return null;
請注意, try-with-resources
至少需要api級別19
public String ifExistIn(String stationName) {
String query = "SELECT stationName FROM review WHERE stationId" +
"='" + stationName + "' OR " + " stationName " + "='" + stationName + "' LIMIT 1";
try (SQLiteDatabase database = this.getWritableDatabase();
Cursor c = database.rawQuery(query, null))
if (cursor.moveToFirst()) {
do {
String stationName = c.getString(c.getColumnIndex("stationName"));
} while (cursor.moveToNext());
}
database.close();
c.close();
return stationName;
}
請始終關閉數據庫和游標
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