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EDIT 4：ハイスコアを保存するために使用しようとしているゲームを持っています。メインメニューから、ViewHighscoresアクティビティを呼び出す「View Highscore」ボタンが押されます。ここからアクティビティは現在保存されているすべてのスコアを表示しようとします。それはデータベースが空であると考え、そのは決してのonCreateに達していないことのように思えるが、私はNullpointerデータベースからカーソルを取り出すときに例外が発生する
package nick.android.com;
import java.util.ArrayList;
import android.app.ListActivity;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
public class ViewHighscores extends ListActivity {
/** Called when the activity is first created. */
private ArrayAdapter<String> myHighscoreAdapter;
private ArrayList<String> myHighscoreMessage = new ArrayList<String>();
ArrayList<Object> data = new ArrayList<Object>();
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.viewhighscores);
myHighscoreAdapter = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, myHighscoreMessage);
setListAdapter(myHighscoreAdapter);
retrieveHighscores();
}
public void retrieveHighscores() {
DatabaseOpenHelper database = new DatabaseOpenHelper(this);
Cursor cursor = database.getHighscore();
if (cursor != null && cursor.getCount() > 0) {
cursor.moveToFirst();
while (cursor.isAfterLast() == false) {
data.add(cursor.getString(0));
data.add(cursor.getString(1));
displayHighscores();
cursor.moveToNext();
}
} else {
myHighscoreAdapter.add("No Highscores Recorded Yet");
}
}
public void displayHighscores() {
myHighscoreAdapter.add("Highscore: " + data);
}
public void returnToMenu(View view) {
finish();
Intent returnToMenuButton = new Intent(view.getContext(),
MainMenu.class);
startActivity(returnToMenuButton);
}
}
がここでもデータベースを書きすぎしようとゲーム自体からのコードの一部である理由を知りません。 getUserName（）; EDITTEXTとnumberOfGuessesからユーザ名がここDatabaseOpenHelperクラスは
package nick.android.com;
import android.content.ContentValues;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.Cursor;
import android.util.Log;
public class DatabaseOpenHelper extends SQLiteOpenHelper {
private static final int DATABASE_VERSION = 2;
private static final String DATABASE_NAME = "HIGHSCORE_DATABASE";
private static final String HIGHSCORE_TABLE = "highscore";
static final String col_HighscoreID = "_id";
static final String col_HighscoreUser = "highscoreuser";
static final String col_Highscore = "highscore";
private SQLiteDatabase db;
DatabaseOpenHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
public void onCreate(SQLiteDatabase db) {
db.execSQL("CREATE TABLE " + HIGHSCORE_TABLE + " (" + col_HighscoreID
+ " INTEGER PRIMARY KEY AUTOINCREMENT, " + col_HighscoreUser
+ " TEXT , " + col_Highscore + " INTEGER)");
System.out.println("ITS GETTING HERE");
inputComputerHighscores();
}
public void inputComputerHighscores() {
ContentValues value = new ContentValues();
SQLiteDatabase db = this.getWritableDatabase();
try {
value.put(col_HighscoreUser, "Gold");
value.put(col_Highscore, "3");
db.insert(HIGHSCORE_TABLE, null, value);
long dbcheck = db.insert(HIGHSCORE_TABLE, null, value);
System.out.println(dbcheck);
value.put(col_HighscoreUser, "Silver");
value.put(col_Highscore, "6");
db.insert(HIGHSCORE_TABLE, null, value);
value.put(col_HighscoreUser, "Bronze");
value.put(col_Highscore, "9");
db.insert(HIGHSCORE_TABLE, null, value);
} catch (Exception e) {
Log.e("DB Error", e.toString());
e.printStackTrace();
}
db.close();
}
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
public Cursor getHighscore() {
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = null;
try {
cursor = db.query(HIGHSCORE_TABLE, new String[] { col_HighscoreID,
col_HighscoreUser, col_Highscore }, null, null, null, null,
col_Highscore + " asc");
} catch (Exception e) {
Log.e("DB Retrieval Error", e.toString());
e.printStackTrace();
}
db.close();
return cursor;
}
public void addHighscore(String Username, int Score) {
ContentValues value = new ContentValues();
value.put(col_HighscoreUser, Username);
value.put(col_Highscore, Score);
SQLiteDatabase db = this.getWritableDatabase();
try {
db.insert(HIGHSCORE_TABLE, null, value);
} catch (Exception e) {
Log.e("DB Error", e.toString());
e.printStackTrace();
}
}
}
1と12
public void saveHighscore() {
scoreSaved = true;
getUserName();
DatabaseOpenHelper database = new DatabaseOpenHelper(this);
database.addHighscore(userName, numberOfGuesses);
}
間の数をあるので、ここで私が< < < CHANGED EDIT ViewHighscores活動を開くとLogcatがある取得5 - それが今力が再びクローズ：
01-13 16:06:17.032: D/AndroidRuntime(444): Shutting down VM
01-13 16:06:17.032: W/dalvikvm(444): threadid=1: thread exiting with uncaught exception (group=0x40015560)
01-13 16:06:17.042: E/AndroidRuntime(444): FATAL EXCEPTION: main
01-13 16:06:17.042: E/AndroidRuntime(444): java.lang.RuntimeException: Unable to start activity ComponentInfo{nick.android.com/nick.android.com.ViewHighscores}: java.lang.IllegalStateException: getWritableDatabase called recursively
01-13 16:06:17.042: E/AndroidRuntime(444): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
01-13 16:06:17.042: E/AndroidRuntime(444): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
01-13 16:06:17.042: E/AndroidRuntime(444): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
01-13 16:06:17.042: E/AndroidRuntime(444): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
01-13 16:06:17.042: E/AndroidRuntime(444): at android.os.Handler.dispatchMessage(Handler.java:99)
01-13 16:06:17.042: E/AndroidRuntime(444): at android.os.Looper.loop(Looper.java:123)
01-13 16:06:17.042: E/AndroidRuntime(444): at android.app.ActivityThread.main(ActivityThread.java:3683)
01-13 16:06:17.042: E/AndroidRuntime(444): at java.lang.reflect.Method.invokeNative(Native Method)
01-13 16:06:17.042: E/AndroidRuntime(444): at java.lang.reflect.Method.invoke(Method.java:507)
01-13 16:06:17.042: E/AndroidRuntime(444): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
01-13 16:06:17.042: E/AndroidRuntime(444): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
01-13 16:06:17.042: E/AndroidRuntime(444): at dalvik.system.NativeStart.main(Native Method)
01-13 16:06:17.042: E/AndroidRuntime(444): Caused by: java.lang.IllegalStateException: getWritableDatabase called recursively
01-13 16:06:17.042: E/AndroidRuntime(444): at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:101)
01-13 16:06:17.042: E/AndroidRuntime(444): at nick.android.com.DatabaseOpenHelper.inputComputerHighscores(DatabaseOpenHelper.java:40)
01-13 16:06:17.042: E/AndroidRuntime(444): at nick.android.com.DatabaseOpenHelper.onCreate(DatabaseOpenHelper.java:33)
01-13 16:06:17.042: E/AndroidRuntime(444): at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:126)
01-13 16:06:17.042: E/AndroidRuntime(444): at android.database.sqlite.SQLiteOpenHelper.getReadableDatabase(SQLiteOpenHelper.java:187)
01-13 16:06:17.042: E/AndroidRuntime(444): at nick.android.com.DatabaseOpenHelper.getHighscore(DatabaseOpenHelper.java:78)
01-13 16:06:17.042: E/AndroidRuntime(444): at nick.android.com.ViewHighscores.retrieveHighscores(ViewHighscores.java:39)
01-13 16:06:17.042: E/AndroidRuntime(444): at nick.android.com.ViewHighscores.onCreate(ViewHighscores.java:31)
01-13 16:06:17.042: E/AndroidRuntime(444): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
01-13 16:06:17.042: E/AndroidRuntime(444): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
01-13 16:06:17.042: E/AndroidRuntime(444): ... 11 more
ViewHighscores.javaの42行目はどれですか？それはNPEが起こっているところです。 – Guillaume
42行目はif（！（cursor == null））です。 –
これは奇妙です、この正確なバージョンのコードでスタックトレースが得られたのでしょうか？それ以来少し変更していないのですか？ – Guillaume