Question

我正在创建一个程序，用于请求用户一个月的销售，并执行销售到条形图。程序运行并正确生成条形;但是文本没有正确执行。我正在尝试将标题“月销售额”作为图表标题，使用销售伙伴名称标记条形图，并在图表左侧标记条形图的值。任何建议都会有所帮助。它在整个图表中反复产生“月度销售”。

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Scanner;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

public class BarGraph extends JPanel
{
 //set variables for graph
     JLabel jLabel1, jLabel2, jLabel3, jLabel4, jLabel5;

    private Map<Color, Integer> bars =
           new LinkedHashMap <>();


    //execute bars and color
    public void addBar(Color color, int value)

   {
      bars.put(color, value);
      repaint();

   }

        //create paint components of chaart
   public void paintComponent(Graphics g)

   {


       Dimension d = getSize();
    int clientWidth = d.width;
    int clientHeight = d.height;
    int max = Integer.MIN_VALUE;
      for (Integer value : bars.values())
      {
         max = Math.max(max, value);
      }
           jLabel1 = new JLabel("Sales For Month", JLabel.CENTER);
        // We can position of the text, relative to the icon:
        jLabel1.setVerticalTextPosition(JLabel.BOTTOM);

        jLabel2 = new JLabel("PAM");
                jLabel3 = new JLabel("Leo");
                jLabel4 = new JLabel("Kim");
        jLabel5 = new JLabel("BOB"); // Label of Icon Only
        // Add labels to the Panel
        add(jLabel1);




      //paint bar
      int width = (getWidth() / bars.size()) - 2;
      int x = 1;
      for (Color color : bars.keySet())
      {
         int value = bars.get(color);
         int height = (int)
                 ((getHeight() -5) * ((double)value /max));
         g.setColor(color);
         g.fillRect(x, getHeight() - height, width, height);
         g.setColor(Color.black);
         g.drawRect(x, getHeight() - height, width, height);
         x += (width + 2);       
      }




   }
   //set bar size
   public Dimension getPreferredSize()
   {
      return new Dimension(bars.size() * 10 + 2, 50);
   }

  //create main to generate charte
  public static void main(String[] args) 
  {
      JFrame frame = new JFrame("Friendly Hal's Auto");
      BarGraph graph = new BarGraph();
      //set frame size
      frame.setSize(350, 300);
      //create variable for user input
      int carsSold1;
      int carsSold2;
      int carsSold3;
      int carsSold4;  

      //request user input

      Scanner input = new Scanner(System.in);
      System.out.println("How many cars did Pam sell for the month?");
      carsSold1 = input.nextInt();        
      System.out.println("How many cars did Leo sell for the month?");
      carsSold2 = input.nextInt();
      System.out.println("How many cars did Kim sell for the month?");
      carsSold3 = input.nextInt();
      System.out.println("How many cars did Bob sell for the month?");
      carsSold4 = input.nextInt();

      //color bar to user choice
     graph.addBar (Color.red, carsSold1);
     graph.addBar (Color.green, carsSold2);
     graph.addBar(Color.blue, carsSold3);
     graph.addBar(Color.yellow, carsSold4);
     frame.getContentPane().add(graph);

     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
     frame.pack();
     frame.setVisible(true);


  }

Answer 1

你的问题是，你已经打破了油漆链......

public void paintComponent(Graphics g)
{
    // Your problem is right here...

    Dimension d = getSize();

paintComponent的其中一项工作是清除Graphics上下文（组件背景颜色）准备好绘画......

在进行任何自定义绘画之前，

首次调用super.paintComponent(g);方法时添加paintComponent

Graphics上下文是共享资源，在给定绘制周期内绘制的所有组件将共享相同的Graphics上下文，在某些系统上，它对于所有绘制周期都是相同的，所以你在使用之前需要确保它已被清除......

有关详细信息，请参阅Painting in AWT and Swing和Performing Custom Painting。

<强>更新

正如@HovercraftFullOfEels指出的那样，您正在paintComponent内创建UI元素，绘画应该绘制UI的当前状态，并且不应对其进行任何修改。当重绘经理认为应该完成时，绘画就完成了，所以你的paintComponent可能被调用很多次，这取决于你在做什么。

从paintComponent中修改UI的状态可能会设置无限循环的重绘请求，最终会占用您的CPU周期并使您的PC无法使用...

也可能想要读取Initial Threads并确保仅在事件调度线程的上下文中创建和修改UI。

你也不应该混合使用基于UI和控制台的方法，它们不能很好地混合在一起......

试图在图表中标记条形图，但多次生成文本

1 个答案: