android - 使用数据库时出现 IndexOutOfBoundsException

Question

我有下一个愚蠢的情况：我想从数据库中读取数据并用这些数据绘制图表。

当我的代码是：

 package com.example.gymforyou;

import java.sql.Date;
import java.text.SimpleDateFormat;

import org.achartengine.ChartFactory;
import org.achartengine.model.TimeSeries;
import org.achartengine.model.XYMultipleSeriesDataset;
import org.achartengine.renderer.XYMultipleSeriesRenderer;
import org.achartengine.renderer.XYSeriesRenderer;

import android.content.Context;
import android.content.Intent;
import android.database.Cursor;
import android.graphics.Color;

import android.util.Log;

public class LineGraph {
    public Intent getIntent(Context context) {
        final String LOG_TAG = "myLogs";
        int countOfRecords = 0;
        countOfRecords=3;
        Date[] x = new Date[countOfRecords];
        double y[] = new double[countOfRecords];
        c.close();
        db.close();
        y[0]=10;
        y[1]=20;
        y[2]=34;
        x[0]=Date.valueOf("2013-04-06");
        x[1]=Date.valueOf("2013-05-06");
            x[2]=Date.valueOf("2013-06-06");
        TimeSeries series = new TimeSeries("Line1");
        for (int i = 0; i < y.length; i++) {
            series.add(x[i], y[i]);
        }
        XYMultipleSeriesDataset dataset = new XYMultipleSeriesDataset();
        dataset.addSeries(series);
        XYMultipleSeriesRenderer mRenderer = new XYMultipleSeriesRenderer();
        XYSeriesRenderer renderer = new XYSeriesRenderer();
        renderer.setDisplayChartValues(true);
        renderer.setColor(Color.RED);
        renderer.setFillPoints(true);
        mRenderer.addSeriesRenderer(renderer);
        mRenderer.setApplyBackgroundColor(true);
        mRenderer.setBackgroundColor(Color.GRAY);

    mRenderer.setShowGrid(true);
    mRenderer.setZoomButtonsVisible(true);

    Intent intent = ChartFactory.getTimeChartIntent(context, dataset,
            mRenderer, "dd-MM-yyyy");


    return intent;
}

} -一切都很好; 但是当我将其更改为：

    package com.example.gymforyou;

import java.sql.Date;
import java.text.SimpleDateFormat;

import org.achartengine.ChartFactory;
import org.achartengine.model.TimeSeries;
import org.achartengine.model.XYMultipleSeriesDataset;
import org.achartengine.renderer.XYMultipleSeriesRenderer;
import org.achartengine.renderer.XYSeriesRenderer;

import android.content.Context;
import android.content.Intent;
import android.database.Cursor;
import android.graphics.Color;

import android.util.Log;

public class LineGraph {
    public Intent getIntent(Context context) {
        final String LOG_TAG = "myLogs";
        DataBase db;
        Cursor c;
        int countOfRecords = 0;
        db = new DataBase(context);
        db.open();
        c = db.getDateAndWeigth();
        countOfRecords = c.getCount();
        Log.d(LOG_TAG, "countOfRecords=" + countOfRecords);
        Date[] x = new Date[countOfRecords];
        double y[] = new double[countOfRecords];

        int j = countOfRecords - 1;
        if (c != null) {
            if (c.moveToFirst()) {
                do {
                    y[j] = c.getDouble(0);
                    x[j] = Date.valueOf(c.getString(1));
                    Log.d(LOG_TAG,
                            "Date" + c.getString(1) + " weigth= "
                                    + c.getDouble(0));
                    Log.d(LOG_TAG, "Record #" +j+ " Secsess");
                    j--;

                } while (c.moveToNext());
            }
        } else
            Log.d(LOG_TAG, "Cursor is null");
        c.close();
        db.close();

        TimeSeries series = new TimeSeries("Line1");
        for (int i = 0; i < y.length; i++) {
            series.add(x[i], y[i]);
        }

        XYMultipleSeriesDataset dataset = new XYMultipleSeriesDataset();

        dataset.addSeries(series);

        XYMultipleSeriesRenderer mRenderer = new XYMultipleSeriesRenderer();

        XYSeriesRenderer renderer = new XYSeriesRenderer();

        renderer.setDisplayChartValues(true);

        renderer.setColor(Color.RED);

        renderer.setFillPoints(true);

        mRenderer.addSeriesRenderer(renderer);

    //  mRenderer.setDisplayValues(true);
        mRenderer.setApplyBackgroundColor(true);

        mRenderer.setBackgroundColor(Color.GRAY);

        mRenderer.setShowGrid(true);

        // mRenderer.setXLabelsAlign(Align.CENTER);
    //  mRenderer.setXTitle("Date");
    //  mRenderer.setXLabels(countOfRecords);
        ;
        mRenderer.setZoomButtonsVisible(true);

        Intent intent = ChartFactory.getTimeChartIntent(context, dataset,
                mRenderer, "dd-MM-yyyy");


        return intent;
    }
}

如果数据库中有 2 条记录，它会起作用，但是当有 3 条记录时，我会收到下一个错误：

我很惊讶，为什么它适用于 DB 中的两条记录，数组中的 3 条记录，但不适用于 DB 中的 3 条记录