import java.util.*;
public class MapTest {
public static void main(String[] args) {
HashMap map=new HashMap();
Random ran=new Random();
for(int i=0;i<50;i++){
int k=ran.nextInt(41);
if(map.get(new Integer(k))==null){
map.put(map.get(new Integer(k)),new Integer(1));
}
else{
Integer d=(Integer)(map.get(map.get(new Integer(k))));
Integer e=new Integer(d.intValue()+1);
map.put(map.get(new Integer(k)),e);
}
}
Set set=map.keySet();
for(Iterator iter=set.iterator();iter.hasNext();){
String key=(String)iter.next();
String value=(String)map.get(key);//第20行异常也就是此处
System.out.println(key+":"+value);
}
}
}
-----------------------------------------------------
执行以上代码会抛出以下异常 是什么意思 什么原因啊
————————————————————————————
Exception in thread "main" java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.String
at test2.MapTest.main(MapTest.java:20)
public class MapTest {
public static void main(String[] args) {
HashMap map=new HashMap();
Random ran=new Random();
for(int i=0;i<50;i++){
int k=ran.nextInt(41);
if(map.get(new Integer(k))==null){
map.put(map.get(new Integer(k)),new Integer(1));
}
else{
Integer d=(Integer)(map.get(map.get(new Integer(k))));
Integer e=new Integer(d.intValue()+1);
map.put(map.get(new Integer(k)),e);
}
}
Set set=map.keySet();
for(Iterator iter=set.iterator();iter.hasNext();){
String key=(String)iter.next();
String value=(String)map.get(key);//第20行异常也就是此处
System.out.println(key+":"+value);
}
}
}
-----------------------------------------------------
执行以上代码会抛出以下异常 是什么意思 什么原因啊
————————————————————————————
Exception in thread "main" java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.String
at test2.MapTest.main(MapTest.java:20)
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Random;
import java.util.Set;
public class test {
/**
* @param args
*/
public static void main(String[] args) {
HashMap map=new HashMap();
Random ran=new Random();
for(int i=0;i<50;i++){
int k=ran.nextInt(41);
if(map.get(new Integer(k))==null){
map.put(map.get(new Integer(k)),new Integer(1));
}
else{
Integer d=(Integer)(map.get(map.get(new Integer(k))));
Integer e=new Integer(d.intValue()+1);
map.put(map.get(new Integer(k)),e);
}
}
Set set=map.keySet();
for(Iterator iter=set.iterator();iter.hasNext();){
String key=(String)iter.next();
String value=String.valueOf(map.get(key)) ;//第20行异常也就是此处
System.out.println(key+":"+value);
}
}}