samplexydataset.java

在软件开发中用来绘制各种图表的源码

/* --------------------
 * SampleXYDataset.java
 * --------------------
 * (C) Copyright 2000-2004, by Object Refinery Limited;
 *
 */

package demo;

import org.jfree.data.general.DatasetChangeEvent;
import org.jfree.data.xy.AbstractXYDataset;
import org.jfree.data.xy.XYDataset;

/**
 * A dummy dataset for an XY plot.
 * <P>
 * Note that the aim of this class is to create a self-contained data source for demo purposes -
 * it is NOT intended to show how you should go about writing your own datasets.
 */
public class SampleXYDataset extends AbstractXYDataset implements XYDataset {

    /** Use the translate to change the data and demonstrate dynamic data changes. */
    private double translate;

    /**
     * Default constructor.
     */
    public SampleXYDataset() {
        this.translate = 0.0;
    }

    /**
     * Returns the translation factor.
     *
     * @return  the translation factor.
     */
    public double getTranslate() {
        return this.translate;
    }

    /**
     * Sets the translation constant for the x-axis.
     *
     * @param translate  the translation factor.
     */
    public void setTranslate(double translate) {
        this.translate = translate;
        notifyListeners(new DatasetChangeEvent(this, this));
    }

    /**
     * Returns the x-value for the specified series and item.  Series are numbered 0, 1, ...
     *
     * @param series  the index (zero-based) of the series.
     * @param item  the index (zero-based) of the required item.
     *
     * @return the x-value for the specified series and item.
     */
    public Number getX(int series, int item) {
        return new Double(-10.0 + this.translate + (item / 10.0));
    }

    /**
     * Returns the y-value for the specified series and item.  Series are numbered 0, 1, ...
     *
     * @param series  the index (zero-based) of the series.
     * @param item  the index (zero-based) of the required item.
     *
     * @return the y-value for the specified series and item.
     */
    public Number getY(int series, int item) {
        if (series == 0) {
            return new Double(Math.cos(-10.0 + this.translate + (item / 10.0)));
        }
        else {
            return new Double(2 * (Math.sin(-10.0 + this.translate + (item / 10.0))));
        }
    }

    /**
     * Returns the number of series in the dataset.
     *
     * @return the number of series in the dataset.
     */
    public int getSeriesCount() {
        return 2;
    }

    /**
     * Returns the key for a series.
     *
     * @param series  the index (zero-based) of the series.
     *
     * @return The key for the series.
     */
    public Comparable getSeriesKey(int series) {
        if (series == 0) {
            return "y = cosine(x)";
        }
        else if (series == 1) {
            return "y = 2*sine(x)";
        }
        else {
            return "Error";
        }
    }

    /**
     * Returns the number of items in the specified series.
     *
     * @param series  the index (zero-based) of the series.
     * @return the number of items in the specified series.
     *
     */
    public int getItemCount(final int series) {
        return 200;
    }

}