JavaApplet额外圈丝印 [英] JavaApplet extra circles printing on screen

问题描述

我在这个新的。我想画一个javaApplet了一圈，但不知何故在输出它显示了3圈。任何想法？

 进口javax.swing.JApplet中;
进口的java.util。*;
进口java.awt中的*。公共类形状扩展JApplet的
{
    公共无效漆（图形页）
    {
        调整（400300）;
        随机兰特=新的随机（）;        //声明常量的大小
        最终诠释circleMax = 160，circleMin = 40; //圈最大和最小直径
        最终诠释locMaxX = 360，locMaxY = 260;
        INT radiusSize = 0，locationx = 0，locationy = 0;        //声明变量
        radiusSize =（rand.nextInt（circleMax）+ circleMin）;
        locationx = 20; // rand.nextInt（locMaxX）+ 20;
        locationy = 20; // rand.nextInt（locMaxY）+ 20;        //绘制圆1
        page.drawOval（locationx，locationy，radiusSize，radiusSize）;
    }
}
 

解决方案

您主要问题是，我们在调用调整（...）绘画方法中和不调用超的画法。话虽如此，我的建议是：

• 不要在一个顶层窗口的（如JApplet的或JFrame中的）paint方法中绘图。


• 相反，它是顶级窗口内显示的JPanel的paintComponent方法中绘图。


• 调用超类的方法，你的画法里面，通常先。

例如

 进口javax.swing.JApplet中;
进口的java.util。*;
进口java.awt中的*。公共类形状扩展JApplet的{    @覆盖
    公共无效的init（）{
        添加（新ShapesPanel（））;
    }}类ShapesPanel继承JPanel {
    私人随机兰特=新的随机（）;
    //声明常量的大小
    最终诠释circleMax = 160，circleMin = 40; //圈最大和最小直径
    最终诠释locMaxX = 360，locMaxY = 260;
    INT radiusSize = 0，locationx = 0，locationy = 0;    公共ShapesPanel（）{
        radiusSize =（rand.nextInt（circleMax）+ circleMin）;
        locationx = 20; // rand.nextInt（locMaxX）+ 20;
        locationy = 20; // rand.nextInt（locMaxY）+ 20;
    }    @覆盖
    保护无效paintComponent（图形页）{
        super.paintComponent方法（页）;
        //绘制圆1
        page.drawOval（locationx，locationy，radiusSize，radiusSize）;
    }
}
 

I am new in this. I am trying to draw a circle in a javaApplet but somehow in the output it shows 3 circles. Any idea?

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

public class Shapes extends JApplet
{
    public void paint (Graphics page)
    {
        resize(400,300);
        Random rand = new Random();

        // Declare size constants
        final int circleMax = 160,circleMin = 40; // circle max and min diameter
        final int locMaxX = 360, locMaxY = 260;
        int radiusSize = 0, locationx = 0,locationy = 0 ;

        // Declare variables
        radiusSize = (rand.nextInt(circleMax)+ circleMin); 
        locationx =20 ;//rand.nextInt(locMaxX)+ 20;
        locationy =20 ;// rand.nextInt(locMaxY) + 20;

        // Draw the circle 1
        page.drawOval(locationx, locationy, radiusSize,radiusSize);
    }
}

解决方案

Your main problems are that you're calling resize(...) within a painting method and are not calling the super's painting method. Having said that, my recommendations are:

• Never draw within a top level window's (such as a JApplet or JFrame's) paint method.
• Instead draw within the paintComponent method of a JPanel that is displayed within the top-level window.
• Call the super's method inside of your painting method, usually first.

For example

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

public class Shapes extends JApplet {

    @Override
    public void init() {
        add(new ShapesPanel());
    }

}    

class ShapesPanel extends JPanel {
    private Random rand = new Random();
    // Declare size constants
    final int circleMax = 160,circleMin = 40; // circle max and min diameter
    final int locMaxX = 360, locMaxY = 260;
    int radiusSize = 0, locationx = 0,locationy = 0 ;

    public ShapesPanel() {
        radiusSize = (rand.nextInt(circleMax)+ circleMin); 
        locationx =20 ;//rand.nextInt(locMaxX)+ 20;
        locationy =20 ;// rand.nextInt(locMaxY) + 20;
    }

    @Override
    protected void paintComponent (Graphics page)   {
        super.paintComponent(page);
        // Draw the circle 1
        page.drawOval(locationx, locationy, radiusSize,radiusSize);
    }
}

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