请教一个ArrayList的问题！！

[wyw020330226]

import java.util.*;

public class ToArrayDemo {

public static void main(String[] args) {
ArrayList alist=new ArrayList();
alist.add(new Integer(1));
alist.add(new Integer(1));
alist.add(new Integer(1));
System.out.println("content of alist"+" "+alist);
Object[] intarray=alist.toArray();
int sum=0;
for (int i = 0; i < intarray.length; i++) //求数组的总和并显示出来
这里不知道怎么怎么求数组的总和并显示出来；




}

}

[interpb]

int sum = 0;
for (int i = 0; i < intarray.length; i++) {
sum+=((Integer)intarray[i]).intValue();
}

[windindance]

for (int i = 0; i < intarray.length; i++)
sum+=intarray[i];

[interpb]

System.out.println(sum);

显示用

[jiaojian843]

package abc;
import java.util.*;
public class aaa {
public static void main(String[] args) {
ArrayList alist=new ArrayList();
alist.add(new Integer(1));
alist.add(new Integer(1));
alist.add(new Integer(1));
System.out.println("content of alist"+" "+alist);
Object[] intarray=alist.toArray();
int sum=0;
for (int i = 0; i < intarray.length; i++){
sum+=((Integer)intarray[i]).intValue();
}
System.out.println(sum);
}
}

[ztc16627]

呵呵,这不是一个关于ArrayList的问题吧.
其实如果你只要求所有Integer的总和,不需要把ArrayList转化成数组的.
package abc;
import java.util.*;
public class aaa {
public static void main(String[] args) {
ArrayList alist=new ArrayList();
alist.add(new Integer(1));
alist.add(new Integer(1));
alist.add(new Integer(1));
System.out.println("content of alist"+" "+alist);
int len = alist.size();
int sum=0;
for(int i=0;i<len;i++){
Integer temp = (Integer)alist.get(i);
sum+=temp.intValue();
}
System.out.println(sum);
}
}

[whyy0]

int[] intarray=new int[alist.size()];
alist.toArray(intarray);

如果直接toArray的话
(Integer)intarray[i]会抛异常