举一个画直线的例子 用main() 解决方案 » 免费领取超大流量手机卡,每月29元包185G流量+100分钟通话, 中国电信官方发货 #include<stdio.h>void main(){for(int i_c=0;i_c<25;i_c++) printf("-");} public void paint(Graphics g) { g.drawLine(10,10,50,10); } class xxxpublic static void main(String args[]){for(int i_c=0;i_c<25;i_c++) System.out.print("-");} import javax.swing.*;import java.awt.event.*;import java.awt.*;import java.awt.image.*;public class DrawLine extends JFrame{public DrawLine(){int x1,y1,x2,y2;this.addMouseListener(new MouseAdapter(){ public void mousePressed(MouseEvent e) { x1 = e.getX(); y1 = e.getY(); } public void mouseReleased(MouseEvent e) { x2 = e.getX(); y2 = e.getY(); getGraphics().drawLine(x1,y1,x2,y2);//此处getGraphics()为什么不对呢?? }});}public static void main(String[] args){DrawLine fm = new DrawLine();fm.setSize(300,300);fm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);fm.setVisible(true);}} 楼上的你没继承Graphics类 不能这样用吧 哦 楼上楼上的你的程式没问题int x1,y1,x2,y2;放到构造方法之外编译没错误 class xxxpublic static void main(String args[]){ System.out.print("-----------------------------------------");} import javax.swing.*;import java.awt.event.*;import java.awt.*;import java.awt.image.*;class DrawLine extends JFrame{ int x1,y1,x2,y2; public DrawLine() { this.setSize(300,300); this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); this.setVisible(true); //int x1,y1,x2,y2; this.addMouseListener(new MouseAdapter() { public void mousePressed(MouseEvent e) { x1 = e.getX(); y1 = e.getY(); } public void mouseReleased(MouseEvent e) { x2 = e.getX(); y2 = e.getY(); getGraphics().drawLine(x1,y1,x2,y2);//此处getGraphics()为什么不对呢?? } }); } public static void main(String[] args) { DrawLine fm = new DrawLine(); //fm.setSize(300,300); //fm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //fm.setVisible(true); }} arr[index++]的问题!! 我是一个初学者,望大家帮助哈我啊!谢谢... 求助,如何 识别 全角英文(字符) ? JAVA虚拟机报错,求高手帮忙,底手勿回!骗分者勿进 简单问题:怎么让我的定时任务连续执行?过来看看,很有意思。 这道关于线程的代码为什么显示找不到符号 关于URL类的问题 有哪位知道Java调用标准DLL的参考书(或地方) 请问:java可以做网络操作系统吗? 我这个循环ip发送写出来 循环端口怎么加进去 找不到servlet的包 请求帮助!
void main()
{
for(int i_c=0;i_c<25;i_c++) printf("-");
}
{
g.drawLine(10,10,50,10);
}
public static void main(String args[])
{
for(int i_c=0;i_c<25;i_c++) System.out.print("-");
}
import java.awt.event.*;
import java.awt.*;
import java.awt.image.*;public class DrawLine extends JFrame
{
public DrawLine()
{
int x1,y1,x2,y2;
this.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
x1 = e.getX();
y1 = e.getY();
}
public void mouseReleased(MouseEvent e)
{
x2 = e.getX();
y2 = e.getY();
getGraphics().drawLine(x1,y1,x2,y2);//此处getGraphics()为什么不对呢??
}
}
);
}
public static void main(String[] args)
{
DrawLine fm = new DrawLine();
fm.setSize(300,300);
fm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
fm.setVisible(true);
}
}
int x1,y1,x2,y2;放到构造方法之外编译没错误
public static void main(String args[])
{
System.out.print("-----------------------------------------");
}
import java.awt.event.*;
import java.awt.*;
import java.awt.image.*;class DrawLine extends JFrame
{
int x1,y1,x2,y2;
public DrawLine()
{
this.setSize(300,300);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setVisible(true);
//int x1,y1,x2,y2;
this.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
x1 = e.getX();
y1 = e.getY();
}
public void mouseReleased(MouseEvent e)
{
x2 = e.getX();
y2 = e.getY();
getGraphics().drawLine(x1,y1,x2,y2);//此处getGraphics()为什么不对呢??
}
});
}
public static void main(String[] args)
{
DrawLine fm = new DrawLine();
//fm.setSize(300,300);
//fm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//fm.setVisible(true);
}
}