JFreeChart条形图生产

Question

我试图创建一个条形图，在for循环中生成一个数据集。

String scores = scoreText.getText(); 
String[] data = scores.split(","); 

DefaultCategoryDataset barChartDataset = null; 

for (int l = 0; l < data.length; l++) { 
    barChartDataset = new DefaultCategoryDataset(); 
     // barChartDataset.setValue(new Double(data[l]), "Scores", stu); 
     barChartDataset.addValue(new Double(data[l]), "Scores", stu); 
     System.out.println(data[l]); 
    } 

    JFreeChart barChart = ChartFactory.createBarChart3D("Summary", "Name", "Scores", barChartDataset, PlotOrientation.VERTICAL, false, true, false); 

的数据是10,5。现在，当数据通过所有这些并生成图形时，仅显示值为5的条。价值10的单独栏在哪里？有谁知道我做错了什么？任何帮助表示赞赏。由于

编辑： 下面是条形图代码：我猜你正在做的一个小失误

String scores = scoreText.getText(); 
    String[] data = scores.split(","); 

    DefaultCategoryDataset barChartDataset = new DefaultCategoryDataset(); 
    //JFreeChart barChart = null; 

    for (int l = 0; l < data.length; l++) { 
     //barChartDataset.addValue(new Double(data[l]), "Scores", stu); 
     barChartDataset.setValue(new Double(data[l]), "Scores", stu); 
     System.out.println(new Double(data[l])); 
    } 

    JFreeChart barChart = ChartFactory.createBarChart3D("Summary", "Name", "Scores", barChartDataset, PlotOrientation.VERTICAL, false, true, false); 

    barChart.setBackgroundPaint(Color.YELLOW); 
    barChart.getTitle().setPaint(Color.RED); 

    final CategoryPlot categoryPlot = barChart.getCategoryPlot(); 

    BarRenderer barRenderer = (BarRenderer) categoryPlot.getRenderer(); 

    DecimalFormat decimalFormat = new DecimalFormat("#.##"); 

    barRenderer.setItemLabelGenerator(new StandardCategoryItemLabelGenerator("{2}", decimalFormat)); 
    categoryPlot.setRenderer(barRenderer); 
    barRenderer.setBasePositiveItemLabelPosition(new ItemLabelPosition(ItemLabelAnchor.OUTSIDE12, TextAnchor.HALF_ASCENT_CENTER)); 
    barRenderer.setItemLabelsVisible(true); 
    barChart.getCategoryPlot().setRenderer(barRenderer); 

    ValueMarker marker = new ValueMarker(7); 

    marker.setLabel("Required Level"); 

    marker.setLabelAnchor(RectangleAnchor.BOTTOM_RIGHT); 

    marker.setLabelTextAnchor(TextAnchor.TOP_RIGHT); 
    marker.setPaint(Color.BLACK); 
    categoryPlot.addRangeMarker(marker); 

    categoryPlot.setRangeGridlinePaint(Color.BLUE); 


    //The JFrame that the bar chart will be in. 
    ChartFrame chartFrame = new ChartFrame("Bar Chart for Parameters", barChart); 
    chartFrame.setVisible(true); 
    chartFrame.setSize(600, 600); 

Answer 1

，即with in for loop for each iteration of loop you are creating a new DefaultCategoryDataset instance。因此，每个每个项目添加到一个单独的DefaultCategoryDataset对象，并最终DefaultCategoryDataset实例具有最后的值被用来创建图表的时候，也就是你让你的图表中只有最后一个值的唯一原因。

解决方案是之外创建DefaultCategoryDataset对象和之前的for循环只有一次这样的：

DefaultCategoryDataset barChartDataset = new DefaultCategoryDataset(); 

for (int l = 0; l < data.length; l++) { 

     // barChartDataset.setValue(new Double(data[l]), "Scores", stu); 
     barChartDataset.addValue(new Double(data[l]), "Scores", stu); 
     System.out.println(data[l]); 
    } 

    JFreeChart barChart = ChartFactory.createBarChart3D("Summary", "Name", "Scores", barChartDataset, PlotOrientation.VERTICAL, false, true, false); 

这里是代码片段我在我的应用程序之一，它是工作的罚款：

DefaultCategoryDataset dataset= new DefaultCategoryDataset(); 
    // Get today as a Calendar.... 
    Calendar today = Calendar.getInstance(); 

for(int i=0; i<15 ;i++) 
    { 
    //get util.Date class object for today date..... 
    java.util.Date today_date=new java.util.Date(today.getTimeInMillis()); 

    //convert date in string format to display on chart..... 
    String today_string_date = new SimpleDateFormat("dd/MM/yy").format(today_date); 

    // set values to DefaultCategoryDataset to display on chart... 
    dataset.setValue(rs1.getInt("login_count"),"Login Frequency", today_string_date); 
    today.add(Calendar.DATE, -1); 

    }// for closing... 

JFreeChart chart = ChartFactory.createBarChart3D("ISIS:Overall login history for last 15 days", "Date -->", "No of user(s) login per day -->", dataset, PlotOrientation.VERTICAL, true, true, false); 

CategoryPlot p = chart.getCategoryPlot(); 
NumberAxis rangeAxis = (NumberAxis) p.getRangeAxis(); 

rangeAxis.setStandardTickUnits(NumberAxis.createIntegerTickUnits()); 
BarRenderer renderer = (BarRenderer) p.getRenderer(); 
DecimalFormat decimalformat1 = new DecimalFormat("##"); 
renderer.setItemLabelGenerator(new StandardCategoryItemLabelGenerator("{2}", decimalformat1)); 
renderer.setItemLabelsVisible(true); 

ChartUtilities.saveChartAsPNG(new File(filePath +"/chart1.png"), chart ,1250, 400); 

我希望它能解决你的问题。