问题
如何在没有以下情况下迭代aSet
/ HashSet
?
Iterator iter = set.iterator();
while (iter.hasNext()) {
System.out.println(iter.next());
}
#1 热门回答(401 赞)
你可以使用anenhanced for loop:
Set<String> set = new HashSet<String>();
//populate set
for (String s : set) {
System.out.println(s);
}
或者使用Java 8:
set.forEach(System.out::println);
#2 热门回答(64 赞)
至少有六种方法可以迭代一组。以下是我所知道的:
方法1
// Obsolete Collection
Enumeration e = new Vector(movies).elements();
while (e.hasMoreElements()) {
System.out.println(e.nextElement());
}
方法2
for (String movie : movies) {
System.out.println(movie);
}
方法3
String[] movieArray = movies.toArray(new String[movies.size()]);
for (int i = 0; i < movieArray.length; i++) {
System.out.println(movieArray[i]);
}
方法4
// Supported in Java 8 and above
movies.stream().forEach((movie) -> {
System.out.println(movie);
});
方法5
// Supported in Java 8 and above
movies.stream().forEach(movie -> System.out.println(movie));
方法6
// Supported in Java 8 and above
movies.stream().forEach(System.out::println);
这是我用于我的例子的HashSet
:
Set<String> movies = new HashSet<>();
movies.add("Avatar");
movies.add("The Lord of the Rings");
movies.add("Titanic");
#3 热门回答(19 赞)
将你的集转换为数组也可以帮助你迭代元素:
Object[] array = set.toArray();
for(int i=0; i<array.length; i++)
Object o = array[i];