第一种:import java.applet.*;
import java.awt.*;
import java.awt.event.*;public class ListTest extends Applet{
L l=new L(3,true);
String msg="";
class L extends List{
L(){
super();
}
L(int a){
super(a);
}
L(int a,boolean b){
super(a,b);
addItemListener(new ItemListener(){
public void itemStateChanged(ItemEvent i){
msg="";
String[] ms=getSelectedItems();
for(int j=0;j<ms.length;j++){
msg+=ms[j];
msg+=" ";
}
repaint(); //为什么运行时这里repaint()起不了预期的作用?
}
});
}
}
public void init(){
l.add("liudehua");
l.add("liangchaowei");
l.add("gutianle");
l.add("rendahua",-1);
l.add("liujialing",1);
l.add("zhangmanyu");
add(l);
} public void paint(Graphics g){
g.drawString(msg, 10, 60);
}
}
======================================================================
第二种:
import java.applet.*;
import java.awt.*;
import java.awt.event.*;public class ListTest extends Applet{
List l=new List(3,true);
String msg="";
public void init(){
l.add("liudehua");
l.add("liangchaowei");
l.add("gutianle");
l.add("rendahua",-1);
l.add("liujialing",1);
l.add("zhangmanyu");
l.addItemListener(new ItemListener(){
public void itemStateChanged(ItemEvent i){
String[] ms=l.getSelectedItems();
for(int j=0;j<ms.length;j++){
msg+=ms[j];
msg+=" ";
}
repaint(); //为什么运行时这里repaint()起不了预期的作用?
msg="";
}
});
add(l);
} public void paint(Graphics g){
g.drawString(msg, 10, 60);
}
}
import java.awt.*;
import java.awt.event.*;public class ListTest extends Applet{
L l=new L(3,true);
String msg="";
class L extends List{
L(){
super();
}
L(int a){
super(a);
}
L(int a,boolean b){
super(a,b);
addItemListener(new ItemListener(){
public void itemStateChanged(ItemEvent i){
msg="";
String[] ms=getSelectedItems();
for(int j=0;j<ms.length;j++){
msg+=ms[j];
msg+=" ";
}
repaint(); //为什么运行时这里repaint()起不了预期的作用?
}
});
}
}
public void init(){
l.add("liudehua");
l.add("liangchaowei");
l.add("gutianle");
l.add("rendahua",-1);
l.add("liujialing",1);
l.add("zhangmanyu");
add(l);
} public void paint(Graphics g){
g.drawString(msg, 10, 60);
}
}
======================================================================
第二种:
import java.applet.*;
import java.awt.*;
import java.awt.event.*;public class ListTest extends Applet{
List l=new List(3,true);
String msg="";
public void init(){
l.add("liudehua");
l.add("liangchaowei");
l.add("gutianle");
l.add("rendahua",-1);
l.add("liujialing",1);
l.add("zhangmanyu");
l.addItemListener(new ItemListener(){
public void itemStateChanged(ItemEvent i){
String[] ms=l.getSelectedItems();
for(int j=0;j<ms.length;j++){
msg+=ms[j];
msg+=" ";
}
repaint(); //为什么运行时这里repaint()起不了预期的作用?
msg="";
}
});
add(l);
} public void paint(Graphics g){
g.drawString(msg, 10, 60);
}
}
import java.applet.*;
import java.awt.*;
import java.awt.event.*;public class Test extends Applet{
List l=new List(3,true);
String msg="";
public void init(){
l.add("liudehua");
l.add("liangchaowei");
l.add("gutianle");
l.add("rendahua",-1);
l.add("liujialing",1);
l.add("zhangmanyu");
l.addItemListener(new ItemListener(){
public void itemStateChanged(ItemEvent i){
msg="";
String[] ms=l.getSelectedItems();
for(int j=0;j<ms.length;j++){
msg+=ms[j];
msg+=" ";
}
repaint(); //为什么运行时这里repaint()起不了预期的作用?
}
});
add(l);
} public void paint(Graphics g){
g.drawString(msg, 10, 60);
}
}
repaint();
msg="";
重画了之后又被你置空了,所以显不出来