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。
packagecom.Elvis.test;importjava.awt.*;publicclassMyFrameextendsFrame{@Overridepublic...
package com.Elvis.test;
import java.awt.*;
public class MyFrame extends Frame {
@Override
public void print(Graphics g) {
g.setColor(Color.red);
g.fillOval(50, 50, 30, 30);
}
public void launchFrame() {
setBounds(400,400,500,300);
this.setVisible(true);
}
public static void main(String[] args) {
new MyFrame().launchFrame();
}
} 展开
import java.awt.*;
public class MyFrame extends Frame {
@Override
public void print(Graphics g) {
g.setColor(Color.red);
g.fillOval(50, 50, 30, 30);
}
public void launchFrame() {
setBounds(400,400,500,300);
this.setVisible(true);
}
public static void main(String[] args) {
new MyFrame().launchFrame();
}
} 展开
4个回答
展开全部
import java.applet.Applet;
import java.awt.Color;
import java.awt.Graphics;
@SuppressWarnings("serial")
public class j extends Applet {
@Override
public void paint(Graphics g) {
// TODO Auto-generated method stub
g.setColor(Color.BLUE);
g.fillOval(0, 0, 100, 20);
super.paint(g);
}
}
或者这个：
import java.applet.*;
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
import java.awt.geom.*;
import java.io.*;
class Point implements Serializable {
int x, y;
Color col;
int tool;
int boarder;
Point(int x, int y, Color col, int tool, int boarder) {
this.x = x;
this.y = y;
this.col = col;
this.tool = tool;
this.boarder = 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, BasicStroke.CAP_BUTT,
BasicStroke.JOIN_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();
ColChoice.add("black");
ColChoice.add("red");
ColChoice.add("blue");
ColChoice.add("green");
ColChoice.addItemListener(this);
// 画笔大小选择
SizeChoice = new Choice();
SizeChoice.add("1");
SizeChoice.add("3");
SizeChoice.add("5");
SizeChoice.add("7");
SizeChoice.add("9");
SizeChoice.addItemListener(this);
// 橡皮大小选择
EraserChoice = new Choice();
EraserChoice.add("5");
EraserChoice.add("9");
EraserChoice.add("13");
EraserChoice.add("17");
EraserChoice.addItemListener(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
clear.addActionListener(this);
eraser.addActionListener(this);
pen.addActionListener(this);
drLine.addActionListener(this);
drCircle.addActionListener(this);
drRect.addActionListener(this);
openPic.addActionListener(this);
savePic.addActionListener(this);
colchooser.addActionListener(this);
颜色 = new Label("画笔颜色", Label.CENTER);
大小B = new Label("画笔大小", Label.CENTER);
大小E = new Label("橡皮大小", Label.CENTER);
// 面板添加组件
toolPanel.add(openPic);
toolPanel.add(savePic);
toolPanel.add(pen);
toolPanel.add(drLine);
toolPanel.add(drCircle);
toolPanel.add(drRect);
toolPanel.add(颜色);
toolPanel.add(ColChoice);
toolPanel.add(大小B);
toolPanel.add(SizeChoice);
toolPanel.add(colchooser);
toolPanel.add(eraser);
toolPanel.add(大小E);
toolPanel.add(EraserChoice);
toolPanel.add(clear);
// 工具面板到APPLET面板
add(toolPanel, BorderLayout.NORTH);
setBounds(60, 60, 900, 600);
setVisible(true);
validate();
// dialog for save and load
openPicture = new FileDialog(this, "打开图画", FileDialog.LOAD);
openPicture.setVisible(false);
savePicture = new FileDialog(this, "保存图画", FileDialog.SAVE);
savePicture.setVisible(false);
openPicture.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
openPicture.setVisible(false);
}
});
savePicture.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
savePicture.setVisible(false);
}
});
addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
}
public void paint(Graphics g) {
Graphics2D g2d = (Graphics2D) g;
Point p1, p2;
n = paintInfo.size();
if (toolFlag == 2)
g.clearRect(0, 0, getSize().width, getSize().height);// 清除
for (int i = 0; i < n; i++) {
p1 = (Point) paintInfo.elementAt(i);
p2 = (Point) paintInfo.elementAt(i + 1);
size = new BasicStroke(p1.boarder, BasicStroke.CAP_BUTT,
BasicStroke.JOIN_BEVEL);
g2d.setColor(p1.col);
g2d.setStroke(size);
if (p1.tool == p2.tool) {
switch (p1.tool) {
case 0:// 画笔
Line2D line1 = new Line2D.Double(p1.x, p1.y, p2.x, p2.y);
g2d.draw(line1);
break;
case 1:// 橡皮
g.clearRect(p1.x, p1.y, p1.boarder, p1.boarder);
break;
case 3:// 画直线
Line2D line2 = new Line2D.Double(p1.x, p1.y, p2.x, p2.y);
g2d.draw(line2);
break;
case 4:// 画圆
Ellipse2D ellipse = new Ellipse2D.Double(p1.x, p1.y,
Math.abs(p2.x - p1.x), Math.abs(p2.y - p1.y));
g2d.draw(ellipse);
break;
case 5:// 画矩形
Rectangle2D rect = new Rectangle2D.Double(p1.x, p1.y,
Math.abs(p2.x - p1.x), Math.abs(p2.y - p1.y));
g2d.draw(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 (e.getSource() == ColChoice)// 预选颜色
{
String name = ColChoice.getSelectedItem();
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 (e.getSource() == SizeChoice)// 画笔大小
{
String selected = SizeChoice.getSelectedItem();
if (selected == "1") {
con = 1;
size = new BasicStroke(con, BasicStroke.CAP_BUTT,
BasicStroke.JOIN_BEVEL);
} else if (selected == "3") {
con = 3;
size = new BasicStroke(con, BasicStroke.CAP_BUTT,
BasicStroke.JOIN_BEVEL);
} else if (selected == "5") {
con = 5;
size = new BasicStroke(con, BasicStroke.CAP_BUTT,
BasicStroke.JOIN_BEVEL);
} else if (selected == "7") {
con = 7;
size = new BasicStroke(con, BasicStroke.CAP_BUTT,
BasicStroke.JOIN_BEVEL);
} else if (selected == "9") {
con = 9;
size = new BasicStroke(con, BasicStroke.CAP_BUTT,
BasicStroke.JOIN_BEVEL);
}
} else if (e.getSource() == EraserChoice)// 橡皮大小
{
String Esize = EraserChoice.getSelectedItem();
if (Esize == "5") {
Econ = 5 * 2;
} else if (Esize == "9") {
Econ = 9 * 2;
} else if (Esize == "13") {
Econ = 13 * 2;
} else if (Esize == "17") {
Econ = 17 * 3;
}
}
}
public void mouseDragged(MouseEvent e) {
Point p1;
switch (toolFlag) {
case 0:// 画笔
x = (int) e.getX();
y = (int) e.getY();
p1 = new Point(x, y, c, toolFlag, con);
paintInfo.addElement(p1);
repaint();
break;
case 1:// 橡皮
x = (int) e.getX();
y = (int) e.getY();
p1 = new Point(x, y, null, toolFlag, Econ);
paintInfo.addElement(p1);
repaint();
break;
default:
}
}
public void mouseMoved(MouseEvent e) {
}
public void update(Graphics g) {
paint(g);
}
public void mousePressed(MouseEvent e) {
Point p2;
switch (toolFlag) {
case 3:// 直线
x = (int) e.getX();
y = (int) e.getY();
p2 = new Point(x, y, c, toolFlag, con);
paintInfo.addElement(p2);
break;
case 4: // 圆
x = (int) e.getX();
y = (int) e.getY();
p2 = new Point(x, y, c, toolFlag, con);
paintInfo.addElement(p2);
paintInfo.addElement(p2);
break;
case 5: // 矩形
x = (int) e.getX();
y = (int) e.getY();
p2 = new Point(x, y, c, toolFlag, con);
paintInfo.addElement(p2);
break;
default:
}
}
public void mouseReleased(MouseEvent e) {
Point p3;
switch (toolFlag) {
case 0:// 画笔
paintInfo.addElement(cutflag);
break;
case 1: // eraser
paintInfo.addElement(cutflag);
break;
case 3:// 直线
x = (int) e.getX();
y = (int) e.getY();
p3 = new Point(x, y, c, toolFlag, con);
paintInfo.addElement(p3);
paintInfo.addElement(cutflag);
repaint();
break;
case 4: // 圆
x = (int) e.getX();
y = (int) e.getY();
p3 = new Point(x, y, c, toolFlag, con);
paintInfo.addElement(p3);
paintInfo.addElement(cutflag);
repaint();
break;
case 5: // 矩形
x = (int) e.getX();
y = (int) e.getY();
p3 = new Point(x, y, c, toolFlag, con);
paintInfo.addElement(p3);
paintInfo.addElement(cutflag);
repaint();
break;
default:
}
}
public void mouseEntered(MouseEvent e) {
}
public void mouseExited(MouseEvent e) {
}
public void mouseClicked(MouseEvent e) {
}
public void actionPerformed(ActionEvent e) {
if (e.getSource() == pen)// 画笔
{
toolFlag = 0;
}
if (e.getSource() == eraser)// 橡皮
{
toolFlag = 1;
}
if (e.getSource() == clear)// 清除
{
toolFlag = 2;
paintInfo.removeAllElements();
repaint();
}
if (e.getSource() == drLine)// 画线
{
toolFlag = 3;
}
if (e.getSource() == drCircle)// 画圆
{
toolFlag = 4;
}
if (e.getSource() == drRect)// 画矩形
{
toolFlag = 5;
}
if (e.getSource() == colchooser)// 调色板
{
Color newColor = JColorChooser.showDialog(this, "调色板", c);
c = newColor;
}
if (e.getSource() == openPic)// 打开图画
{
openPicture.setVisible(true);
if (openPicture.getFile() != null) {
int tempflag;
tempflag = toolFlag;
toolFlag = 2;
repaint();
try {
paintInfo.removeAllElements();
File filein = new File(openPicture.getDirectory(),
openPicture.getFile());
picIn = new FileInputStream(filein);
VIn = new ObjectInputStream(picIn);
paintInfo = (Vector) VIn.readObject();
VIn.close();
repaint();
toolFlag = tempflag;
} catch (ClassNotFoundException IOe2) {
repaint();
toolFlag = tempflag;
System.out.println("can not read object");
} catch (IOException IOe) {
repaint();
toolFlag = tempflag;
System.out.println("can not read file");
}
}
}
if (e.getSource() == savePic)// 保存图画
{
savePicture.setVisible(true);
try {
File fileout = new File(savePicture.getDirectory(),
savePicture.getFile());
picOut = new FileOutputStream(fileout);
VOut = new ObjectOutputStream(picOut);
VOut.writeObject(paintInfo);
VOut.close();
} catch (IOException IOe) {
System.out.println("can not write object");
}
}
}
}// end paintboard
public class pb {
public static void main(String args[]) {
new paintboard("画图程序");
}
}
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图像处理等多媒体操作需要使用paint(Graphics)方法来完成
本问题中的print方法改为paint方法，并且调用后应该就可以了
本问题中的print方法改为paint方法，并且调用后应该就可以了
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launchFrame()方法中并没有调用print(Graphics g)方法，当然不能显示画的椭圆了。
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应该是paint方法，不是print
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