Question

构建一个TODO列表应用程序，用于在SQL数据库中保存用户Edittext数据，但是当我单击该按钮时它会崩溃但重新启动而不保存用户输入错误

Logcat错误

<er-response id="100053">
   <payload>
      <modify-usergroup-reponse>
         <success>true</success>
         <reason-code>
            <code>0</code>
            <sub-code>0</sub-code>
            <name>OK</name>
         </reason-code>
      </modify-usergroup-reponse>
   </payload>
</er-response>

点击方法

0

8-06 23:36:23.018 2904-2904/com.naive.LISTY E/SQLiteLog: (1) table tasks has no column named date
08-06 23:36:23.019 2904-2904/com.naive.LISTY E/SQLiteDatabase: Error inserting date=12/12/12 Description=hello world title=Hello time=12:50
                                                               android.database.sqlite.SQLiteException: table tasks has no column named date (code 1): , while compiling: INSERT INTO tasks(date,Description,title,time) VALUES (?,?,?,?)
                                                                   at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
                                                                   at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:887)
                                                                   at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:498)
                                                                   at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
                                                                   at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
                                                                   at android.database.sqlite.SQLiteStatement.<init>(SQLiteStatement.java:31)
                                                                   at android.database.sqlite.SQLiteDatabase.insertWithOnConflict(SQLiteDatabase.java:1469)
                                                                   at android.database.sqlite.SQLiteDatabase.insert(SQLiteDatabase.java:1341)
                                                                   at listy.naive.com.listy.Dialog.Add_task(Dialog.java:63)
                                                                   at java.lang.reflect.Method.invoke(Native Method)
                                                                   at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:284)
                                                                   at android.view.View.performClick(View.java:5198)
                                                                   at android.view.View$PerformClick.run(View.java:21147)
                                                                   at android.os.Handler.handleCallback(Handler.java:739)
                                                                   at android.os.Handler.dispatchMessage(Handler.java:95)
                                                                   at android.os.Looper.loop(Looper.java:148)
                                                                   at android.app.ActivityThread.main(ActivityThread.java:5417)
                                                                   at java.lang.reflect.Method.invoke(Native Method)
                                                                   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
                                                                   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

光标代码

public void Add_task(View view) {

    EditText mTitle = (EditText)findViewById(R.id.title_field);
    String Title = String.valueOf(mTitle.getText());

     EditText mTask = (EditText)findViewById(R.id.description_field);
     String Task = String.valueOf(mTask.getText());

    EditText mDate = (EditText) findViewById(R.id.date_field);
    String Date = String.valueOf(mDate.getText());

    EditText mTime = (EditText) findViewById(R.id.time_field);
    String Time = String.valueOf(mTime.getText());

    SQLiteDatabase db = mHelper.getWritableDatabase();
    ContentValues values = new ContentValues();
    values.put(TaskContract.TaskEntry.COL_TASK_TITLE, Title);
    values.put(TaskContract.TaskEntry.COL_TASK_DESCRIPTION, Task);
    values.put(TaskContract.TaskEntry.COL_TASK_DATE, Date);
    values.put(TaskContract.TaskEntry.COL_TASK_TIME, Time);

    db.insert(TaskContract.TaskEntry.TABLE, null, values);
    //updateUI();
    //db.close();
}

mHelper

private Cursor updateUI() {
    ArrayList<String> taskList = new ArrayList<>();
    SQLiteDatabase db = mHelper.getReadableDatabase();
    Cursor cursor = db.query(TaskContract.TaskEntry.TABLE,
            new String[]{TaskContract.TaskEntry._ID, TaskContract.TaskEntry.COL_TASK_TITLE, TaskContract.TaskEntry.COL_TASK_DESCRIPTION, TaskContract.TaskEntry.COL_TASK_DATE, TaskContract.TaskEntry.COL_TASK_TIME},
            null, null, null, null, null);
    return cursor;}

Answer 1

我认为mHelper是null。我认为你没有初始化mHelper。

Answer 2

此行导致NullPointerException：

SQLiteDatabase db = mHelper.getWritableDatabase();

您尚未在任何地方初始化mHelper，因此您获得了例外。你需要添加：

MySQLiteOpenHelper mHelper = new MySQLiteOpenHelper(parameters);

MySQLiteOpenHelper是你的一类，它扩展了SQLiteOpenHelper并覆盖了你需要的一些方法。

修改在使用SQLiteOpenHelper的实施编辑问题后，请执行以下操作：

TaskDbHelper mHelper = new TaskDbHelper(this);

如果您在活动中传递this，并且在片段中，请将getActivity()作为参数传递。

无法执行android的方法：onClick

2 个答案: