java - 在 sqlite 上插入时 SQLite android NullPointerException

Question

我知道存在类似的问题，但我发现的所有问题都与没有 SQLiteDatabase 实例有关。

我的 onCreate 方法中创建数据库的表定义之一如下所示:

db.execSQL("CREATE TABLE offers(" +
            "    game_state_id   INTEGER NOT NULL REFERENCES game_states (id)," +
            "    city_id         INTEGER NOT NULL REFERENCES cities (id)," +
            "    item_id         INTEGER NOT NULL REFERENCES items (id)," +
            "    sell_price      INTEGER NOT NULL," +
            "    buy_price       INTEGER NOT NULL," +
            "    amount          INTEGER NOT NULL DEFAULT 0," +
            "    UNIQUE (game_state_id, city_id, item_id)" +
            ")");

它正在工作，数据库看起来很好。

public long createGameState() {
    SQLiteDatabase db = this.getWritableDatabase();

    ContentValues values = new ContentValues();
    values.put("name", "default");
    values.put("current_city_id", getInitialCityId());
    // it could return -1 if insert didn't work
    long res = db.insert("game_states", null, values);

    List<City> cities = loadCities();
    List<Item> items = loadItems();
    Log.d("Kupiec", "Itemki: "+String.valueOf(items.size())+" | Miasta: "+String.valueOf(cities.size()));

    for (City city : cities) {
        for (Item item : items) {
            ContentValues values2 = new ContentValues();
            values2.put("item_id", item.id);
            values2.put("city_id", city.id);
            values2.put("game_state_id", res);
            values2.put("buy_price", Utils.getRandom(100, 125));
            values2.put("sell_price", Utils.getRandom(75, 100));
            values2.put("amount", Utils.getRandom(15, 30));
            Log.d("Kupiec", "offer_values: "+values2.toString());
            db.insert("offers", null, values2);
        }
    }

    db.close();
    return res;
}

有趣的是，第一次插入到 game_states 表中工作正常，但是它在循环中的第一次插入时中断。

06-12 13:28:03.872      630-630/com.mippit.kupiec E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.IllegalStateException: Could not execute method of the activity
    at android.view.View$1.onClick(View.java:3044)
    at android.view.View.performClick(View.java:3511)
    at android.view.View$PerformClick.run(View.java:14105)
    at android.os.Handler.handleCallback(Handler.java:605)
    at android.os.Handler.dispatchMessage(Handler.java:92)
    at android.os.Looper.loop(Looper.java:137)
    at android.app.ActivityThread.main(ActivityThread.java:4424)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:511)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
    at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.reflect.InvocationTargetException
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:511)
    at android.view.View$1.onClick(View.java:3039)
    at android.view.View.performClick(View.java:3511)
    at android.view.View$PerformClick.run(View.java:14105)
    at android.os.Handler.handleCallback(Handler.java:605)
    at android.os.Handler.dispatchMessage(Handler.java:92)
    at android.os.Looper.loop(Looper.java:137)
    at android.app.ActivityThread.main(ActivityThread.java:4424)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:511)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
    at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
    at android.database.sqlite.SQLiteStatement.releaseAndUnlock(SQLiteStatement.java:290)
    at android.database.sqlite.SQLiteStatement.executeInsert(SQLiteStatement.java:115)
    at android.database.sqlite.SQLiteDatabase.insertWithOnConflict(SQLiteDatabase.java:1718)
    at android.database.sqlite.SQLiteDatabase.insert(SQLiteDatabase.java:1591)
    at com.mippit.kupiec.Repository.createGameState(Repository.java:182)
    at com.mippit.kupiec.Repository.createNewGame(Repository.java:153)
    at com.mippit.kupiec.MainActivity.clicked_new_game(MainActivity.java:42)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:511)
    at android.view.View$1.onClick(View.java:3039)
    at android.view.View.performClick(View.java:3511)
    at android.view.View$PerformClick.run(View.java:14105)
    at android.os.Handler.handleCallback(Handler.java:605)
    at android.os.Handler.dispatchMessage(Handler.java:92)
    at android.os.Looper.loop(Looper.java:137)
    at android.app.ActivityThread.main(ActivityThread.java:4424)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:511)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
    at dalvik.system.NativeStart.main(Native Method)

发生什么事了？出现此错误的第 182 行是 db.insert("offers", null,values2);

的行

我得到了很好的答案，但作者删除了它，可能是因为他得到了 2 票反对(不是我!)。 如果有人可以将其退回，请这样做，我很乐意将其标记为已接受。

最后，正确的答案是try {...} catch {}这个NullPointerException并再次加载数据库。我不明白为什么会发生这种情况，因为我认为 db 将打开，直到我明确地说 db.close()，但是，它正在工作。

Answer 1

我发现问题是您已经在具有不同表的数据库中插入了值，并且在不关闭它的情况下尝试再次插入。所以冲突是存在的。替换 for 循环语句

db.insert("offers", null, values2);

与

db.insertWithOnConflict("table name", null, "values", SQLiteDatabase.CONFLICT_IGNORE);