java 画数学函数图

java 画数学函数图不太方便，需要用第三方包 jfree，安装或下载方法网上有。

要用到 jfree 里面的 XYSeries，生成一系列数据。

然后根据生成的数据，使用 chart 描点画图。

举例：

1. 画图 y= x^2

import javax.swing.JFrame;

import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartFrame;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.data.xy.XYSeries;
import org.jfree.data.xy.XYSeriesCollection;

public class DrawMath {

	public static void main(String[] args) {

		XYSeries series = new XYSeries("xySeries");
		for (int x = -100; x < 100; x++) {
			int y = x*x;
			series.add(x, y);
		}
		
		XYSeriesCollection dataset = new XYSeriesCollection();
		dataset.addSeries(series);
		JFreeChart chart = ChartFactory.createXYLineChart(
				"y = x^2", // chart title
				"x", // x axis label
				"x^2", // y axis label
				dataset, // data
				PlotOrientation.VERTICAL,
				false, // include legend
				false, // tooltips
				false // urls
				);

		ChartFrame frame = new ChartFrame("my picture", chart);
		frame.pack();
		frame.setVisible(true);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	}

}

显示效果：

 

 

2. 画图 y= sin(x)

import javax.swing.JFrame;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartFrame;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.data.xy.XYSeries;
import org.jfree.data.xy.XYSeriesCollection;

public class DrawMath {

	public static void main(String[] args) {

		XYSeries series = new XYSeries("xySeries");
		for (double x = -10; x < 10; x = x + 0.1) {
			double y = Math.sin(x);
			series.add(x, y);
		}
		
		XYSeriesCollection dataset = new XYSeriesCollection();
		dataset.addSeries(series);
		JFreeChart chart = ChartFactory.createXYLineChart(
				"y = sin(x)", // chart title
				"x", // x axis label
				"sin(x)", // y axis label
				dataset, // data
				PlotOrientation.VERTICAL,
				false, // include legend
				false, // tooltips
				false // urls
				);

		ChartFrame frame = new ChartFrame("my picture", chart);
		frame.pack();
		frame.setVisible(true);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);	
	}
}

显示效果：

 

3. 画散点图

画散点图时，要用到 plot 与 render 进一步设置了。

举例：

import javax.swing.JFrame;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartFrame;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.chart.plot.XYPlot;
import org.jfree.chart.renderer.xy.XYLineAndShapeRenderer;
import org.jfree.data.xy.XYSeries;
import org.jfree.data.xy.XYSeriesCollection;

public class DrawMath {

	public static void main(String[] args) {

		XYSeries series = new XYSeries("xySeries");
		for (double x = -10; x < 10; x = x + 0.1) {
			double y = Math.sin(x);
			series.add(x, y);
		}
		
		XYSeriesCollection dataset = new XYSeriesCollection();
		dataset.addSeries(series);
		JFreeChart chart = ChartFactory.createXYLineChart(
				"y = sin(x)", // chart title
				"x", // x axis label
				"sin(x)", // y axis label
				dataset, // data
				PlotOrientation.VERTICAL,
				false, // include legend
				false, // tooltips
				false // urls
				);
		
		XYPlot plot = (XYPlot)chart.getPlot();
		XYLineAndShapeRenderer renderer = new XYLineAndShapeRenderer();
		renderer.setSeriesLinesVisible(0, false); // 设置连线不可见
	        plot.setRenderer(renderer);
		
		ChartFrame frame = new ChartFrame("my picture", chart);
		frame.pack(); // fit window to figure size
		frame.setVisible(true);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);	
	}
}

 

显示效果：