Android的SQLite的空指针异常 [英] Android SQLite Null Pointer Exception

问题描述

我得到这个在LogCat中：

I am getting this in LogCat:

05-20 17:16:34.721: E/AndroidRuntime(30461): FATAL EXCEPTION: main
05-20 17:16:34.721: E/AndroidRuntime(30461): java.lang.NullPointerException
05-20 17:16:34.721: E/AndroidRuntime(30461):    at android.database.sqlite.SQLiteStatement.releaseAndUnlock(SQLiteStatement.java:290)
05-20 17:16:34.721: E/AndroidRuntime(30461):    at android.database.sqlite.SQLiteStatement.executeUpdateDelete(SQLiteStatement.java:96)
05-20 17:16:34.721: E/AndroidRuntime(30461):    at android.database.sqlite.SQLiteDatabase.updateWithOnConflict(SQLiteDatabase.java:1810)
05-20 17:16:34.721: E/AndroidRuntime(30461):    at android.database.sqlite.SQLiteDatabase.update(SQLiteDatabase.java:1761)
05-20 17:16:34.721: E/AndroidRuntime(30461):    at com.kickinglettuce.debtplannerpro.DebtDataSource.updateDebt(DebtDataSource.java:130)
05-20 17:16:34.721: E/AndroidRuntime(30461):    at com.kickinglettuce.debtplannerpro.manageDebts$4.onClick(manageDebts.java:184)
05-20 17:16:34.721: E/AndroidRuntime(30461):    at android.view.View.performClick(View.java:3511)
05-20 17:16:34.721: E/AndroidRuntime(30461):    at android.view.View$PerformClick.run(View.java:14105)
05-20 17:16:34.721: E/AndroidRuntime(30461):    at android.os.Handler.handleCallback(Handler.java:605)
05-20 17:16:34.721: E/AndroidRuntime(30461):    at android.os.Handler.dispatchMessage(Handler.java:92)
05-20 17:16:34.721: E/AndroidRuntime(30461):    at android.os.Looper.loop(Looper.java:137)
05-20 17:16:34.721: E/AndroidRuntime(30461):    at android.app.ActivityThread.main(ActivityThread.java:4447)
05-20 17:16:34.721: E/AndroidRuntime(30461):    at java.lang.reflect.Method.invokeNative(Native Method)
05-20 17:16:34.721: E/AndroidRuntime(30461):    at java.lang.reflect.Method.invoke(Method.java:511)
05-20 17:16:34.721: E/AndroidRuntime(30461):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
05-20 17:16:34.721: E/AndroidRuntime(30461):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
05-20 17:16:34.721: E/AndroidRuntime(30461):    at dalvik.system.NativeStart.main(Native Method)

下面是与它相关的code：

Here is the code associated with it:

protected void onListItemClick(ListView l, View v, int position, long id) {

    List<Debt> values = datasource.getAllDebt();
            datasource.open();

    Debt item = values.get(position);
    final long boxId = item.getId();
    // final String BoxId = String.valueOf(boxId);
    final String BoxName = item.getName();
    final String BoxBalance = item.getBalance();
    final String BoxApr = item.getApr();
    final String BoxPayment = item.getPayment();

    // set up dialog
    final Dialog dialog = new Dialog(manageDebts.this);
    dialog.setContentView(R.layout.custom_dialog);
    dialog.setTitle("Edit Debt Details");
    dialog.setCancelable(true);

    // set up text
    TextView tv1 = (TextView) dialog.findViewById(R.id.textView1);
    TextView tv2 = (TextView) dialog.findViewById(R.id.textView2);
    TextView tv3 = (TextView) dialog.findViewById(R.id.textView3);
    TextView tv4 = (TextView) dialog.findViewById(R.id.textView4);
    EditText et1 = (EditText) dialog.findViewById(R.id.editText1);
    EditText et2 = (EditText) dialog.findViewById(R.id.editText2);
    EditText et3 = (EditText) dialog.findViewById(R.id.editText3);
    EditText et4 = (EditText) dialog.findViewById(R.id.editText4);

    tv1.setText("Debt Description");
    tv2.setText("Balance");
    tv3.setText("APR");
    tv4.setText("Monthly Payment");

    et1.setText(BoxName);
    et2.setText(BoxBalance);
    et3.setText(BoxApr);
    et4.setText(BoxPayment);

    // set up button
    Button button = (Button) dialog.findViewById(R.id.button1);
    button.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {


            datasource.updateDebt(Long.valueOf(boxId), BoxName, BoxBalance, BoxApr,
                    BoxPayment);
            dialog.dismiss();

        }
    });

    datasource.close();

    dialog.show();
}

和我的数据库类的更新方法：

And the Update Method in my database class:

public boolean updateDebt(long updateId, String debtName, String debtTotal,
        String debtApr, String paymentGoal) {

     ContentValues values = new ContentValues();
     values.put(MySQLiteHelper.COLUMN_DEBT_NAME, debtName);
     values.put(MySQLiteHelper.COLUMN_DEBT_TOTAL, debtTotal);
     values.put(MySQLiteHelper.COLUMN_APR, debtApr);
     values.put(MySQLiteHelper.COLUMN_PAYMENT, paymentGoal);
     String whereClause = MySQLiteHelper.COLUMN_ID + " = ?";
     String[] whereArgs = new String[]{ String.valueOf(updateId) };
     return database.update(MySQLiteHelper.TABLE_DEBT,
             values, whereClause, whereArgs) > 0;
}

有什么建议？

推荐答案

看起来你试图访问数据库时，它已关闭。也许把datasource.open（）在的onCreate和datasource.close（）在的onCreate（年底年初），并要求他们每人只有一次在你的类将解决您的问题。

Looks like your trying to access the db when it's been closed. Perhaps placing datasource.open() at the beginning of onCreate and datasource.close() at the end of onCreate() and calling them each just once in your class would solve your problem.

如果您正在编辑，创建和删除，需要多次调用数据库中的活动项目，考虑调用datasource.open（）在访问数据库的方法的开头，然后关闭（）在该月底方法。

If you are editing, creating and deleting items in your activity requiring multiple calls to your database, consider calling datasource.open() at the beginning of a method that accesses the database and then close() at the end of of that method.

这篇关于Android的SQLite的空指针异常的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！