更新数据库中的数据

Question

每次添加任务时，我的程序都将要执行的任务列表，该程序应将其保存在数据库中。

我遇到的问题是它不会更新以前保存的任务。

每当我登录该应用程序时，我都应该找到将它们添加到数据库中的任务。

我不知道问题出在哪里。

这是我的代码：

Todo 类：

public class Todo implements Parcelable 
{
    private String title;
    private String status;
    private String priority;
    private String date;
    private String time;
}

TodoDAO 类：

public long updateTodo (Todo todo)
{
        db = dbHelper.getWritableDatabase();

        String whereClause = TodoTable.COLUMN_NAME_TITLE + " =? " + TodoTable.COLUMN_NAME_STATUS + " =? "

                             +TodoTable.COLUMN_NAME_PRIORITY + " =? "+  TodoTable.COLUMN_NAME_DATE+ " =? "

                             +TodoTable.COLUMN_NAME_TIME + " =? " ;

        String whereArgu [] =  {todo.getTitle() ,todo.getStatus() , todo.getPriority() , todo.getDate() , todo.getTime() };

        ContentValues values =  changeTodoToContentobject( todo);

        return  db.update(TodoTable.TABLE_NAME , values, whereClause  ,  whereArgu );
}

TodoDBHelper 类：

public class TodoDBHelper extends SQLiteOpenHelper  implements  Contract
{
private static final String DATABASE_NAME = "todo.db";

private static final int VERSION = 1;

private static final String SQL_CREATE_TODO_TABLE =
        " CREATE TABLE " + TodoTable.TABLE_NAME +

                " ( " + TodoTable._ID + " INTEGER PRIMARY KEY AUTOINCREMENT , "
                      + TodoTable.COLUMN_NAME_TITLE    + "  TEXT , "+
                        TodoTable.COLUMN_NAME_STATUS   + "  TEXT , "+
                        TodoTable.COLUMN_NAME_PRIORITY + "  TEXT , "+
                        TodoTable.COLUMN_NAME_DATE     + "  TEXT , "+
                        TodoTable.COLUMN_NAME_TIME     + " TEXT ); " ;



private static final String SQL_DELETE_TODO_TABLE =
        " DROP TABLE IF EXISTS " + TodoTable.TABLE_NAME +  " ; " ;



public TodoDBHelper(Context context) {
    super(context, DATABASE_NAME, null, VERSION);

}


@Override
public void onCreate(SQLiteDatabase db) {

    db.execSQL(SQL_CREATE_TODO_TABLE);

}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    db.execSQL(SQL_DELETE_TODO_TABLE);
    onCreate(db);

}
}

界面合同：

public interface Contract {

class TodoTable implements BaseColumns{

    public static final String TABLE_NAME = "todo";
    public static final String COLUMN_NAME_STATUS = "status";
    public static final String COLUMN_NAME_PRIORITY = "priority";
    public static final String COLUMN_NAME_TITLE = "title";
    public static final String COLUMN_NAME_DATE= "date";
    public static final String COLUMN_NAME_TIME = "time";
}