Question

我的JPanel应该包含300行文本，但无论我做什么来扩大它的大小，它都不会包含所有300行文本，为什么以及如何修复？这是我的代码：

import java.awt.*;
import javax.swing.*;
import java.util.*;

public class My_Chart_Panel extends JPanel
{
  String Label_Text="                       -10  -9  -8  -7  -6  -5  -4  -3  -2  -1   0   1   2   3   4   5   6   7   8   9   10";
  Vector<String> String_Vector=new Vector();
  Font Times_New_Roman_15_Font=new Font("Times New Roman",0,15);

  My_Chart_Panel()
  {
    for (int i=0;i<300;i++) String_Vector.add("Line : "+(i+1));
    JScrollPane Chart_ScrollPane=new JScrollPane(new A_Chart_Panel(String_Vector));
    Chart_ScrollPane.setPreferredSize(new Dimension(536,770));
    Chart_ScrollPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
    Chart_ScrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);

    JPanel Top_Panel=new JPanel();
    JLabel Top_Label=new JLabel(Label_Text);
    Top_Label.setForeground(new Color(0,50,160));
    Top_Label.setFont(Times_New_Roman_15_Font);
    Top_Panel.add(Top_Label);
    add("North",Top_Panel);

    add("Center",Chart_ScrollPane);
    JPanel Bottom_Panel=new JPanel();
    JLabel Bottom_Label=new JLabel(Label_Text);
    Bottom_Label.setForeground(new Color(0,50,160));
    Bottom_Label.setFont(Times_New_Roman_15_Font);
    Bottom_Panel.add(Bottom_Label);
    add("South",Bottom_Panel);

    setPreferredSize(new Dimension(536,900));
  }

  public static void main(String[] args)
  {
    JFrame f=new JFrame("My_Chart_Panel");
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.add(new My_Chart_Panel());
    f.setSize(560,910);
    f.setLocationRelativeTo(null);
    f.setVisible(true);
  }
}

class A_Chart_Panel extends JPanel
{
  Vector<String> String_Vector;
  final int PAD=2;

  A_Chart_Panel(Vector<String> String_Vector)
  {
    this.String_Vector=String_Vector;
    setPreferredSize(new Dimension(530,String_Vector.size()*8));
    Draw_Chart();
  }

  void Draw_Chart()
  {
    Out("String_Vector.size() = "+String_Vector.size());
  }

  protected void paintComponent(Graphics g)
  {
    super.paintComponent(g);
    Graphics2D g2=(Graphics2D) g;
    g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_ON);
    int w=getWidth();
    int h=getHeight();
    g2.drawLine(PAD+w*9/15,PAD,PAD+w*9/15,h-PAD);
    g2.drawLine(PAD+w*9/15,PAD,PAD+w*9/15-5,PAD+26);
    g2.drawLine(PAD+w*9/15,PAD,PAD+w*9/15+5,PAD+26);   

    double xScale=(w-2*PAD)/(20);
    double maxValue=100.0;
    double yScale =(h-2*PAD)/maxValue;
    // The origin location.  
    int x0=PAD;
    int y0=h-PAD;
    g2.setPaint(Color.BLUE);
    for (int j=0;j<String_Vector.size();j++)
    {
      int x=x0+(int)(xScale*(j+1));
      int y=20+(int)(yScale*j);
      g2.drawString(String_Vector.elementAt(j),5,y);
    }
  }

  private static void out(String message) { System.out.print(message); }
  private static void Out(String message) { System.out.println(message); }
}

Answer 1

我明白了，这是答案：

class A_Chart_Panel extends JPanel
{
  Vector<String> String_Vector;
  final int PAD=2;

  A_Chart_Panel(Vector<String> String_Vector)
  {
    this.String_Vector=String_Vector;
    setPreferredSize(new Dimension(530,String_Vector.size()*12));
    Draw_Chart();
  }

  void Draw_Chart()
  {
    Out("String_Vector.size() = "+String_Vector.size());
  }

  protected void paintComponent(Graphics g)
  {
    super.paintComponent(g);
    Graphics2D g2=(Graphics2D) g;
    g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_ON);
    int w=getWidth();
    int h=getHeight();
    g2.drawLine(PAD+w*9/15,PAD,PAD+w*9/15,h-PAD);
    g2.drawLine(PAD+w*9/15,PAD,PAD+w*9/15-5,PAD+26);
    g2.drawLine(PAD+w*9/15,PAD,PAD+w*9/15+5,PAD+26);   

    double xScale=(w-2*PAD)/(20);
    double maxValue=String_Vector.size();
    double yScale =(h-2*PAD)/maxValue;
    // The origin location.  
    int x0=PAD;
    int y0=h-PAD;
    g2.setPaint(Color.BLUE);
    for (int j=0;j<String_Vector.size();j++)
    {
      int x=x0+(int)(xScale*(j+1));
      int y=10+(int)(yScale*j);
      g2.drawString(String_Vector.elementAt(j),5,y);
    }
  }

为什么JPanel在我的应用程序中没有所有行？

1 个答案: