??? 應用jfreechart來畫圖需要兩個jar包：jfreechart.jar和jcommon.jar，直接去官網下載就成：

https://sourceforge.net/projects/jfreechart/files/

?? 下載完成後解壓，然後將jfreechart.jar和jcommon.jar兩個包導入到需要畫表的項目中，導入的方法：

右擊項目所在的包，選中Build Path，然後選擇? Configure?Build Path，點擊Libraries，再點擊Add External JARS，將上述兩個包添加進去就可以用啦

最近在寫排序算法，忽然想對比一下各種排序算法的實際運行時間，所以畫個圖表可以更加直觀的進行比較。

代碼實現畫折線圖

class?chart{?
????????//?步驟1：創建CategoryDataset對象（準備數據）?
????CategoryDataset?dataset?=?createDataset();??
????CategoryDataset?dataset1?=?createDataset1();
????//?步驟2：根據Dataset?生成JFreeChart對象，以及做相應的設置??
????JFreeChart?freeChart?=?createChart(dataset);?
????JFreeChart?freeChart1?=?createChart1(dataset1);?
????
????
????//根據CategoryDataset創建JFreeChart對象
????public?static?JFreeChart?createChart(CategoryDataset?categoryDateset){
????????
????????//?創建JFreeChart對象：ChartFactory.createLineChart??
????????JFreeChart?jfreechart?=?ChartFactory.createLineChart("The?Confrontation?Of?Sorts?In?Best?Case",?//?標題
????????????????"Sort?By",?????????//categoryAxisLabel?（category軸，橫軸，X軸標簽）
????????????????"Spent?Time",??????//?valueAxisLabel（value軸，縱軸，Y軸的標簽）
????????????????categoryDateset,??//Dataset??
????????????????PlotOrientation.VERTICAL,?false,?//?legend?
????????????????false,??????????//Tooltips
????????????????false);????????//URLs
????????
????????//?使用CategoryPlot設置各種參數。??
????????CategoryPlot?plot?=?(CategoryPlot)jfreechart.getPlot();??
????????
????????//?背景色?透明度??
????????plot.setBackgroundAlpha(0.5f);??
????????
????????//?前景色?透明度??
????????plot.setForegroundAlpha(1.0f);??
????????
????????//?其他設置?參考?CategoryPlot類??
????????LineAndShapeRenderer?renderer?=?(LineAndShapeRenderer)plot.getRenderer();??
????????renderer.setBaseShapesVisible(true);?//?series?點（即數據點）可見??
????????renderer.setBaseLinesVisible(true);?//?series?點（即數據點）間有連線可見??
????????renderer.setUseSeriesOffset(true);?//?設置偏移量??
????????renderer.setBaseItemLabelGenerator(new?StandardCategoryItemLabelGenerator());??
????????renderer.setBaseItemLabelsVisible(true);??
????????return?jfreechart;??
????}
????
????public?static?CategoryDataset?createDataset()?{??
????????String[]?rowKeys?=?{"Sort"};??
????????String[]?colKeys?=?{"HeapSort","ShellSort","BubbleSort","QuickSort","RadixSort","SimpleSort"};??
????????
????????double[][]?data?=?{{TimeChat.btime_Heap,TimeChat.btime_Shell,TimeChat.btime_Bubble,TimeChat.btime_Quick,TimeChat.btime_Radix,TimeChat.btime_Simple},};???
????????//System.out.println(TimeChat.btime_Heap);
????????return?DatasetUtilities.createCategoryDataset(rowKeys,?colKeys,?data);??
????}
????
????//最壞情況下
?????public?static?JFreeChart?createChart1(CategoryDataset?categoryDateset){
????????
????????//?創建JFreeChart對象：ChartFactory.createLineChart??
????????JFreeChart?jfreechart?=?ChartFactory.createLineChart("The?Confrontation?Of?Sorts?In?Worst?Case",?//?標題
????????????????"Sort?By",???????????//categoryAxisLabel?（category軸，橫軸，X軸標簽）?
????????????????"Spent?Time",???????//valueAxisLabel（value軸，縱軸，Y軸的標簽）
????????????????categoryDateset,????//?Dataset
????????????????PlotOrientation.VERTICAL,?false,?//?legend?
????????????????false,????????????//Tooltips?
????????????????false);??????????//?URLs?
????????
?
????????CategoryPlot?plot?=?(CategoryPlot)jfreechart.getPlot();?
????????plot.setBackgroundAlpha(0.5f);???
????????plot.setForegroundAlpha(0.5f);
????????LineAndShapeRenderer?renderer?=?(LineAndShapeRenderer)plot.getRenderer();?
????????renderer.setBaseShapesVisible(true);?//?series?點（即數據點）可見?
????????renderer.setBaseLinesVisible(true);?//?series?點（即數據點）間有連線可見?
????????renderer.setUseSeriesOffset(true);?//?設置偏移量?
????????renderer.setBaseItemLabelGenerator(new?StandardCategoryItemLabelGenerator());?
????????renderer.setBaseItemLabelsVisible(true);?
????????return?jfreechart;?
?????}
?????
?????public?static?CategoryDataset?createDataset1()?{?
????????String[]?rowKeys?=?{"Sort"};?
????????String[]?colKeys?=?{"HeapSort","ShellSort","BubbleSort","QuickSort","RadixSort","SimpleSort"};?
???????
????????double[][]?data?=?{{TimeChat.wtime_Heap,TimeChat.wtime_Shell,TimeChat.wtime_Bubble,TimeChat.wtime_Quick,TimeChat.wtime_Radix,TimeChat.wtime_Simple},};??
????????//System.out.println(TimeChat.btime_Heap);
????????return?DatasetUtilities.createCategoryDataset(rowKeys,?colKeys,?data);?
????}
?????
}

將圖表建好之後需要借助ChartPanel類將其顯示出來，或者可以將生成的圖表以圖片格式保存到本地，我選擇將它直接顯示出來：

public?class?TimeChart{
?????public?static?void?main(String[]?strings){
??????????TimeChat?tc?=?new?TimeChat();?//另一個類，初始化data[][]中的變量
??????????chart?ct?=?new?chart();
??????????ChartPanel?chartf?=?new?ChartPanel(ct.freeChart,true);
??????????ChartPanel?chartf1?=?new?ChartPanel(ct.freeChart1,true);
??????????JFrame?jf?=?new?JFrame();
??????????jf.add(chartf,BorderLayout.WEST);
??????????jf.add(chartf1,BorderLayout.EAST);
??????????jf.setVisible(true);
??????????jf.setSize(1400,?600);
??????????jf.setLocationRelativeTo(null);
?????}
}

運行效果如下

Java畫折線圖