java - 找不到符号方法Iterator()

Question

大家好，我已经开始学习 Java 中的集合并尝试编写一个简单的程序，但我遇到了 2 个错误，请查看并帮助我。

import java.util.Iterator;
import java.util.*;
    class ArrayListDemo1{
    public static void main(String... s){
    ArrayList<Integer> al = new ArrayList<Integer>();
 // ArrayList al = new ArrayList();
    int x[] = {1, -1, 2, -2, 3, -3, 4, -4};
    for(int i=0; i<x.length;i++){
        al.add(x[i]);
    }
    System.out.println(al);
//  Iterator<Integer> i = al.Iterator();
    Iterator i = al.Iterator();
    while(i.hasNext()){
        Integer z = (Integer)i.next();
//      Integer z = i.next();
        if(z.intValue < 0)  
        i.remove(); 
    }   
    System.out.println(al);
}
}

Answer 1

 1. Iterator i = al.iterator();//here method is case sensitive
 2. intValue() not intValue, is a method.