java 作为整数的迭代器
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Iterator as an integer
提问by MMCXCVII
As far as I?know, an Iterator is an object which type is defined during its declaration but which also comes with two other methods: hasNext()and next().
So, besides those two methods, if I write Iterator<Integer> iterator, then iterator is supposed to behave like an Integer object.
However, when I try to use iterator.intValue(), I get an error.
据我所知，迭代器是一个对象，其类型在其声明期间定义，但还带有其他两个方法：hasNext()和next()。所以，除了这两种方法，如果我写Iterator<Integer> iterator，那么迭代器应该表现得像一个 Integer 对象。但是，当我尝试使用 时iterator.intValue()，出现错误。
Exception in thread "main" java.lang.Error: Unresolved compilation problems:
The method intValue() is undefined for the type Class<capture#1-of ? extends Iterator>
Syntax error, insert "}" to complete Block
Here is the full code:
这是完整的代码：
Iterator<Integer> iterator = content.iterator(); //content is a HashSet<Integer> object
System.out.println(iterator.intValue());
while(iterator.hasNext())
{
iterator.next();
System.out.println(iterator);
}
回答by Greg Valcourt
You need to get the Integer from the iterator, then print that Integer:
您需要从迭代器中获取整数，然后打印该整数：
Integer i = iterator.next();
System.out.println(i);
An Iterator is an iterator for integers, it doesn't behave like an integer. The next method will return an Integer.
Iterator 是整数的迭代器，它的行为不像整数。下一个方法将返回一个整数。
回答by Mureinik
No, an Iterator<T>does not act like a T- its next()method, however, returns a T value. I.e.:
不， anIterator<T>不像 a T- 它的next()方法，但是，返回一个 T value。IE：
while(iterator.hasNext()) {
Integer myInteger = iterator.next();
int myInt = myInteger.intValue();
}
回答by Peter Lawrey
An Iterator is not an Integer, though it might give you one if you call next()Instead of calling the Iterator directly is usually better to use a for-each loop which was added to Java 5.0 in 2006.
Iterator 不是 Integer，但如果您调用它可能会给您一个，next()而不是直接调用 Iterator 通常最好使用 2006 年添加到 Java 5.0 的 for-each 循环。
for(int n : content) //content is a HashSet<Integer> object
System.out.println(n);
From Java 8 you can use the forEach method.
从 Java 8 开始，您可以使用 forEach 方法。
content.forEach(System.out::println);
回答by afroz1198
More Precisely,iterator.next()returns an Object type variable.So,typecastingis necessary
更准确地说，iterator.next()返回一个 Object 类型的变量。所以，typecasting是必要的
Integer myInteger = (Integer) iterator.next();
int i = myInteger.intValue();
