用eclipse最新版 java1.7 写一个小的测试程序，在一个窗口画一个椭圆，窗口有了但是椭圆显示不出来。_CMS教程

import javaappletApplet;

import javaawtColor;

import javaawtGraphics;

@SuppressWarnings("serial")

public class j extends Applet {

@Override

public void paint(Graphics g) {

// TODO Auto-generated method stub

gsetColor(ColorBLUE);

gfillOval(0, 0, 100, 20);

superpaint(g);

}

或者这个：

import javaapplet;

import javaawt;

import javaawtevent;

import javautil;

import javaxswing;

import javaawtgeom;

import javaio;

class Point implements Serializable {

int x, y;

Color col;

int tool;

int boarder;

Point(int x, int y, Color col, int tool, int boarder) {

thisx = x;

thisy = y;

thiscol = col;

thistool = tool;

thisboarder = boarder;

}

class paintboard extends Frame implements ActionListener, MouseMotionListener,

MouseListener, ItemListener {

int x = -1, y = -1;

int con = 1;// 画笔大小

int Econ = 5;// 橡皮大小

int toolFlag = 0;// toolFlag:工具标记

// toolFlag工具对应表：

// （0--画笔）；（1--橡皮）；（2--清除）；

// （3--直线）；（4--圆）；（5--矩形）；

Color c = new Color(0, 0, 0); // 画笔颜色

BasicStroke size = new BasicStroke(con, BasicStrokeCAP_BUTT,

BasicStrokeJOIN_BEVEL);// 画笔粗细

Point cutflag = new Point(-1, -1, c, 6, con);// 截断标志

Vector paintInfo = null;// 点信息向量组

int n = 1;

FileInputStream picIn = null;

FileOutputStream picOut = null;

ObjectInputStream VIn = null;

ObjectOutputStream VOut = null;

// 工具面板--画笔，直线，圆，矩形，多边形,橡皮，清除/

Panel toolPanel;

Button eraser, drLine, drCircle, drRect;

Button clear, pen;

Choice ColChoice, SizeChoice, EraserChoice;

Button colchooser;

Label 颜色, 大小B, 大小E;

// 保存功能

Button openPic, savePic;

FileDialog openPicture, savePicture;

paintboard(String s) {

super(s);

addMouseMotionListener(this);

addMouseListener(this);

paintInfo = new Vector();

/ 各工具按钮及选择项 /

// 颜色选择

ColChoice = new Choice();

ColChoiceadd("black");

ColChoiceadd("red");

ColChoiceadd("blue");

ColChoiceadd("green");

ColChoiceaddItemListener(this);

// 画笔大小选择

SizeChoice = new Choice();

SizeChoiceadd("1");

SizeChoiceadd("3");

SizeChoiceadd("5");

SizeChoiceadd("7");

SizeChoiceadd("9");

SizeChoiceaddItemListener(this);

// 橡皮大小选择

EraserChoice = new Choice();

EraserChoiceadd("5");

EraserChoiceadd("9");

EraserChoiceadd("13");

EraserChoiceadd("17");

EraserChoiceaddItemListener(this);

toolPanel = new Panel();

clear = new Button("清除");

eraser = new Button("橡皮");

pen = new Button("画笔");

drLine = new Button("画直线");

drCircle = new Button("画圆形");

drRect = new Button("画矩形");

openPic = new Button("打开图画");

savePic = new Button("保存图画");

colchooser = new Button("显示调色板");

// 各组件事件监听

clearaddActionListener(this);

eraseraddActionListener(this);

penaddActionListener(this);

drLineaddActionListener(this);

drCircleaddActionListener(this);

drRectaddActionListener(this);

openPicaddActionListener(this);

savePicaddActionListener(this);

colchooseraddActionListener(this);

颜色 = new Label("画笔颜色", LabelCENTER);

大小B = new Label("画笔大小", LabelCENTER);

大小E = new Label("橡皮大小", LabelCENTER);

// 面板添加组件

toolPaneladd(openPic);

toolPaneladd(savePic);

toolPaneladd(pen);

toolPaneladd(drLine);

toolPaneladd(drCircle);

toolPaneladd(drRect);

toolPaneladd(颜色);

toolPaneladd(ColChoice);

toolPaneladd(大小B);

toolPaneladd(SizeChoice);

toolPaneladd(colchooser);

toolPaneladd(eraser);

toolPaneladd(大小E);

toolPaneladd(EraserChoice);

toolPaneladd(clear);

// 工具面板到APPLET面板

add(toolPanel, BorderLayoutNORTH);

setBounds(60, 60, 900, 600);

setVisible(true);

validate();

// dialog for save and load

openPicture = new FileDialog(this, "打开图画", FileDialogLOAD);

openPicturesetVisible(false);

savePicture = new FileDialog(this, "保存图画", FileDialogSAVE);

savePicturesetVisible(false);

openPictureaddWindowListener(new WindowAdapter() {

public void windowClosing(WindowEvent e) {

openPicturesetVisible(false);

}

});

savePictureaddWindowListener(new WindowAdapter() {

public void windowClosing(WindowEvent e) {

savePicturesetVisible(false);

}

});

addWindowListener(new WindowAdapter() {

public void windowClosing(WindowEvent e) {

Systemexit(0);

}

});

}

public void paint(Graphics g) {

Graphics2D g2d = (Graphics2D) g;

Point p1, p2;

n = paintInfosize();

if (toolFlag == 2)

gclearRect(0, 0, getSize()width, getSize()height);// 清除

for (int i = 0; i < n; i++) {

p1 = (Point) paintInfoelementAt(i);

p2 = (Point) paintInfoelementAt(i + 1);

size = new BasicStroke(p1boarder, BasicStrokeCAP_BUTT,

BasicStrokeJOIN_BEVEL);

g2dsetColor(p1col);

g2dsetStroke(size);

if (p1tool == p2tool) {

switch (p1tool) {

case 0:// 画笔

Line2D line1 = new Line2DDouble(p1x, p1y, p2x, p2y);

g2ddraw(line1);

break;

case 1:// 橡皮

gclearRect(p1x, p1y, p1boarder, p1boarder);

break;

case 3:// 画直线

Line2D line2 = new Line2DDouble(p1x, p1y, p2x, p2y);

g2ddraw(line2);

break;

case 4:// 画圆

Ellipse2D ellipse = new Ellipse2DDouble(p1x, p1y,

Mathabs(p2x - p1x), Mathabs(p2y - p1y));

g2ddraw(ellipse);

break;

case 5:// 画矩形

Rectangle2D rect = new Rectangle2DDouble(p1x, p1y,

Mathabs(p2x - p1x), Mathabs(p2y - p1y));

g2ddraw(rect);

break;

case 6:// 截断，跳过

i = i + 1;

break;

default:

}// end switch

}// end if

}// end for

}

public void itemStateChanged(ItemEvent e) {

if (egetSource() == ColChoice)// 预选颜色

{

String name = ColChoicegetSelectedItem();

if (name == "black") {

c = new Color(0, 0, 0);

} else if (name == "red") {

c = new Color(255, 0, 0);

} else if (name == "green") {

c = new Color(0, 255, 0);

} else if (name == "blue") {

c = new Color(0, 0, 255);

}

} else if (egetSource() == SizeChoice)// 画笔大小

{

String selected = SizeChoicegetSelectedItem();

if (selected == "1") {

con = 1;