java - Android SQLiteException。为什么会发生这种情况？

Question

这是从SQLiteDatebase获取表RECORD的代码。在 try block 中出现问题并且总是抛出 SQLiteException。我在这里想做的就是将表“RECORD”的每一行转换为字符串并将其添加到 ArrayList 中，然后将数组连接到 ArrayAdapter，最后使用ListView来显示数组。

package com.example.tommy.stop_watch_real;

import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ArrayAdapter;
import android.widget.CursorAdapter;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
import android.widget.Toast;

import java.util.ArrayList;

public class RecordList extends AppCompatActivity {


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_record_list);
        ListView temp = (ListView) findViewById(R.id.recordList);
        ArrayList<String> arrayList = new ArrayList<String>();
        ArrayAdapter<String> adapter;

        **try {
            SQLiteOpenHelper dataBaseHelper = new DataBaseHelper(this);
            SQLiteDatabase db = dataBaseHelper.getReadableDatabase();
            Cursor cursor = db.query("RECORD", new String[] {"_id, DATE, MINUTES"}, null, null,null,null,null);
            while (cursor.moveToFirst()){
                String id = Integer.toString(cursor.getInt(0));
                String date = cursor.getString(1);
                String minutes = Integer.toString(cursor.getInt(2));
                String finalValue = id + "|" + date + "|" + minutes;
                arrayList.add(finalValue);
            }
            adapter=new ArrayAdapter<String>(this,
                    android.R.layout.simple_list_item_1,
                    arrayList);
            temp.setAdapter(adapter);
            cursor.close();
            db.close();}**
            catch (SQLiteException e) {
                Toast.makeText(RecordList.this, "Database not available", Toast.LENGTH_LONG).show();
        }

    }
}

这是我的 datebaseHelper 的代码:

class DataBaseHelper extends SQLiteOpenHelper {
    private static final String DB_NAME = "Record"; // name of the database
    private static final int DB_VERSION = 1; //Version

    DataBaseHelper (Context context){
        super(context, DB_NAME, null, DB_VERSION);
    }

    public void onCreate(SQLiteDatabase db) {
        db.execSQL("CREATE TABLE RECORD ("
                + "_id INTEGER PRIMARY KEY AUTOINCERMENT, "
                + "DATE STRING," //careful
                + "MINUTES INTEGER" + ");"
        );
    }
    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
    //no need to worry about this yet.
    }
}

toast 总是出现，这意味着 try block 中出现了错误。我一周前刚刚开始android开发，我不知道我的代码出了什么问题。如果您能给我一些指导，那就太好了。

提前谢谢您。

Answer 1

这部分对我来说似乎是错误的。

 while (cursor.moveToFirst()){
            String id = Integer.toString(cursor.getInt(0));
            String date = cursor.getString(1);
            String minutes = Integer.toString(cursor.getInt(2));
            String finalValue = id + "|" + date + "|" + minutes;
            arrayList.add(finalValue);
        }

我不确定您想要实现什么目标，但从数据库获取数据的正确方法是这样的:

 cursor.moveToFirst()
 while (cursor.isAfterLast()){
            String id = Integer.toString(cursor.getInt(0));
            String date = cursor.getString(1);
            String minutes = Integer.toString(cursor.getInt(2));
            String finalValue = id + "|" + date + "|" + minutes;
            arrayList.add(finalValue);
        }