我正在学习校园里的队列，并且我们的某个实验室遇到了问题我相信问题就在这里，问题是它在达到50后不会擦除圈子
public void paint(Graphics g)
{
int incX = 5; // initial x increment for circle locations
int incY = 5; // initial y increment for circle locations
Coord temp = new Coord(0,0);
Queue<Coord> q = new LinkedList<Coord>();
Circle c = new Circle(g,circleSize,incX,incY,TIME_DELAY);
try
{
for(int i = 1; i <= TOTAL_NUM_CIRCLES; i++)
{
if(q.size() >= 50)
{
temp = q.remove();
c.eraseCircle(g,temp.getX(),temp.getY());
}
temp = new Coord(getX(),getY());
q.add(temp);
c.drawCircle(g);
c.hitEdge();
}
}
catch(InterruptedException e){}
}
如果你需要在这里运行或测试的全部内容都是评论，说明一切是什么以及我正在尝试做什么
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;
/**
* Creates an instance of the GfxApp class, which uses the Circle class, Coord class, and
* a queue to create a screen saver.
* @param args not used
*/
public class ScreenSaver
{
public static void main(String args[])
{
GfxApp gfx = new GfxApp();
}
}
/**
* Creates a Screen Saver by placing Circle coordinates in a queue
*/
class GfxApp extends JFrame
{
private int circleCount, circleSize;
public static final int TIME_DELAY = 10; // controls the speed
public static final int TOTAL_NUM_CIRCLES = 1000; // controls how long it goes
/**
* Creates a GfxApp with 50 circles with diameter 30
*/
public GfxApp()
{
circleCount = 50;
circleSize = 30;
setSize(800,600);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setVisible(true);
}
/**
* Draws a stream of circleCount circles of size circleSize. Uses a queue to erase circles
* at the end of the stream. The total number of circles that will be drawn is 2000.
* @param g the Graphics object
*/
public void paint(Graphics g)
{
int incX = 5; // initial x increment for circle locations
int incY = 5; // initial y increment for circle locations
Coord temp = new Coord(0,0);
Queue<Coord> q = new LinkedList<Coord>();
Circle c = new Circle(g,circleSize,incX,incY,TIME_DELAY);
try
{
for(int i = 1; i <= TOTAL_NUM_CIRCLES; i++)
{
if(q.size() >= 50)
{
temp = q.remove();
c.eraseCircle(g,temp.getY(),temp.getX());
}
temp = new Coord(getX(),getY());
q.add(temp);
c.drawCircle(g);
c.hitEdge();
}
}
catch(InterruptedException e){}
}
}
/**
* A class to represent Circle objects. Circles can be drawn and erased.
*/
class Circle
{
private int tlX; // top-left X coordinate
private int tlY; // top-left Y coordinate
private int incX; // increment movement of X coordinate
private int incY; // increment movement of Y coordinate
private boolean addX; // flag to determine add/subtract of increment for X
private boolean addY; // flag to determine add/subtract of increment for Y
private int size; // diameter of the circle
private int timeDelay; // time delay until next circle is drawn
/**
* Creates a Circle with a specified Graphics, size, x increment, y increment and time delay
*/
public Circle(Graphics g, int s, int x, int y, int td)
{
incX = x;
incY = y;
size = s;
addX = true;
addY = false;
tlX = 400;
tlY = 300;
timeDelay = td;
}
/**
* returns the top left X of this circle
* @return tlX
*/
public int getTLX() { return tlX;}
/**
* returns the top left Y of this circle
* @return tlY
*/
public int getTLY() { return tlY;}
/**
* delays the program for a specified number of miliseconds
* @param n number of miliseconds
*/
public void delay(int n) throws InterruptedException
{
Thread.sleep(n);
}
/**
* draws a blue circle and sets the tlX and tlY for the next drawing
* @param g Graphics object
*/
public void drawCircle(Graphics g) throws InterruptedException
{
g.setColor(Color.blue);
g.drawOval(tlX,tlY,size,size);
delay(timeDelay);
if (addX)
tlX+=incX;
else
tlX-=incX;
if (addY)
tlY+=incY;
else
tlY-=incY;
}
/**
* Randomly sets a new direction for the circle by randomly setting
* the x increment and y increment
*/
public void newData()
{
incX = (int) Math.round(Math.random() * 7 + 5);
incY = (int) Math.round(Math.random() * 7 + 5);
}
/**
* Determines if any of the four edges have been hit, and if so, reverses the
* appropriate flags (addX and addY) and calls newData
*/
public void hitEdge()
{
boolean a = false;
if (tlX < incX)
{
addX = true;
a = true;
}
if (tlX > 800 - (30 + incX))
{
addX = false;
a = true;
}
if (tlY < incY + 30)
{
addY = true;
a = true;
}
if (tlY > 600 - (30 + incY))
{
addY = false;
a = true;
}
if (a)
newData();
}
// add an eraseCircle method
public void eraseCircle(Graphics g, int x, int y)
{
g.setColor(Color.black);
g.drawOval(x,y,size,size);
}
}
// Create a Coord class, so that coordinates of drawn circles can be placed in the queue.
// As coordinates are removed from the queue, circles are erased with eraseCircle.
class Coord
{
private int x;
private int y;
public Coord(int a, int b)
{
x=a;
y=b;
}
public int getX(){return x;}
public int getY(){return y;}
public int setX(int a){x=a; return x;}
public int setY(int b){y=b; return y;}
}
答案 0 :(得分：0)
你的坐标是向后的：
-public void eraseCircle(Graphics g, int x, int y)
-c.eraseCircle(g,temp.getY(),temp.getX());
切换x和y，它应该可以工作。
编辑： 好的问题是你的坐标中的x和y总是为0所以我修改了你的drawCircle方法来返回正确的坐标，你的paint方法来存储它们，所以这就是你得到的：
漆：
public void paint(Graphics g)
{
int incX = 5; // initial x increment for circle locations
int incY = 5; // initial y increment for circle locations
Coord temp = new Coord(0,0);
Queue<Coord> q = new LinkedList<Coord>();
Circle c = new Circle(g,circleSize,incX,incY,TIME_DELAY);
try
{
for(int i = 1; i <= TOTAL_NUM_CIRCLES; i++)
{
if(q.size() >= 50)
{
temp = q.remove();
c.eraseCircle(g,temp.getX(),temp.getY());
}
temp = new Coord(getX(),getY());
//q.add(temp);
q.add(c.drawCircle(g));
c.hitEdge();
}
}
catch(InterruptedException e){}
}
画圆：
/**
* draws a blue circle and sets the tlX and tlY for the next drawing
* @param g Graphics object
* @return
*/
public Coord drawCircle(Graphics g) throws InterruptedException
{
g.setColor(Color.blue);
g.drawOval(tlX,tlY,size,size);
delay(timeDelay);
if (addX)
tlX+=incX;
else
tlX-=incX;
if (addY)
tlY+=incY;
else
tlY-=incY;
return new Coord(tlX, tlY);
}
为了确定这一点，我在paint方法中设置了一个断点，并通过eclipses调试器查看了temp的值。