我的JFrame没有显示拨号

Question

的输出。这是我的DialPlot类：

public class Demo { 

    private DefaultValueDataset dataset = new DefaultValueDataset(0); 

    private ChartPanel buildDialPlot(int minimumValue=0,int maximumValue,int majorTickGap) { 

     DialPlot plot = new DialPlot(dataset); 
     plot.setDialFrame(new StandardDialFrame()); 
     plot.addLayer(new DialValueIndicator(0)); 
     plot.addLayer(new DialPointer.Pointer()); 
     int redLine =maximumValue/5 + 10; 
     plot.addLayer(new StandardDialRange(maximumValue, redLine,   Color.blue)); 
     plot.addLayer(new StandardDialRange(redLine, minimumValue, Color.red)); 

     StandardDialScale scale = new StandardDialScale(minimumValue, 
     maximumValue, -120, -300, majorTickGap, majorTickGap - 1); 
     scale.setTickRadius(0.88); 
     scale.setTickLabelOffset(0.20); 
     scale.setTickLabelsVisible(false); 
     plot.addScale(0, scale); 

     return new ChartPanel(new JFreeChart(plot)) { 

     @Override 
     public Dimension getPreferredSize() { 
      return new Dimension(300, 300); 
      } 
     }; 
    } 
} 

这是我JFrame GUI类

public class NewJFrame extends javax.swing.JFrame { 
    Demo d=new Demo(); 
    int minimumValue=0; 
    int maximumValue=100; 
    int majorTickGap=1; 

    public NewJFrame() { 
    initComponents(); 
    d.buildDialPlot(minimumValue,maximumValue,majorTickGap); 
    this.pack(); 
    this.setLocationRelativeTo(null); 
    } 

我还添加了它在JFrame GUI类是这样的：

this.add(d.buildDialPlot(minimumValue,maximumValue,majorTickGap)); 

它显示相同的结果为空JFrame。 任何人都知道我的错误是什么？

Answer 1

艺术最小的，你需要通过add()返回buildDialPlot()向JFrame的ChartPanel。一个完整的例子显示为here。

public NewJFrame() { 
    initComponents(); 
    ChartPanel cp = d.buildDialPlot(minimumValue, maximumValue, majorTickGap); 
    this.add(cp); 
    this.pack(); 
    this.setLocationRelativeTo(null); 
} 

附录：使用方法建议here，下面的例子将您Demo到局部声明JFrame。

为试：

import java.awt.Color; 
import java.awt.Dimension; 
import java.awt.EventQueue; 
import javax.swing.JFrame; 
import org.jfree.chart.ChartPanel; 
import org.jfree.chart.JFreeChart; 
import org.jfree.chart.plot.dial.DialPlot; 
import org.jfree.chart.plot.dial.DialPointer; 
import org.jfree.chart.plot.dial.DialValueIndicator; 
import org.jfree.chart.plot.dial.StandardDialFrame; 
import org.jfree.chart.plot.dial.StandardDialRange; 
import org.jfree.chart.plot.dial.StandardDialScale; 
import org.jfree.data.general.DefaultValueDataset; 

/** 
* @see https://stackoverflow.com/a/38906326/230513 
*/ 
public class Test { 

    private void display() { 
     JFrame f = new JFrame("Test"); 
     f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     Demo d = new Demo(); 
     ChartPanel cp = d.buildDialPlot(0, 100, 10); 
     f.add(cp); 
     f.pack(); 
     f.setLocationRelativeTo(null); 
     f.setVisible(true); 
    } 

    private static class Demo { 

     private DefaultValueDataset dataset = new DefaultValueDataset(0); 

     private ChartPanel buildDialPlot(int minimumValue, int maximumValue, int majorTickGap) { 

      DialPlot plot = new DialPlot(dataset); 
      plot.setDialFrame(new StandardDialFrame()); 
      plot.addLayer(new DialValueIndicator(0)); 
      plot.addLayer(new DialPointer.Pointer()); 
      int redLine = maximumValue/5 + 10; 
      plot.addLayer(new StandardDialRange(maximumValue, redLine, Color.blue)); 
      plot.addLayer(new StandardDialRange(redLine, minimumValue, Color.red)); 

      StandardDialScale scale = new StandardDialScale(minimumValue, 
       maximumValue, -120, -300, majorTickGap, majorTickGap - 1); 
      scale.setTickRadius(0.88); 
      scale.setTickLabelOffset(0.20); 
      scale.setTickLabelsVisible(false); 
      plot.addScale(0, scale); 

      return new ChartPanel(new JFreeChart(plot)) { 

       @Override 
       public Dimension getPreferredSize() { 
        return new Dimension(300, 300); 
       } 
      }; 
     } 
    } 

    public static void main(String[] args) { 
     EventQueue.invokeLater(new Test()::display); 
    } 
}