JAVA中集合输出的四种方式

在JAVA中Collection输出有四种方式，分别如下:

一） Iterator输出。 该方式适用于Collection的所有子类。

public class Hello
{
public static void main(String[] args) throws Exception
{
Set<Person> javaProgramers = new HashSet<Person>();
javaProgramers.add(new Person("aaron",25));
javaProgramers.add(new Person("larry", 32));
javaProgramers.add(new Person("jesse", 33));
javaProgramers.add(new Person("mike",65));
javaProgramers.add(new Person("jesse",33));

Iterator<Person> iter = javaProgramers.iterator();
while(iter.hasNext())
{
System.out.println(iter.next());
}
}
}

二）foreach输出。该方式适用于Collection的所有子类。

public class Hello
{
public static void main(String[] args) throws Exception
{
Set<Person> javaProgramers = new HashSet<Person>();
javaProgramers.add(new Person("aaron",25));
javaProgramers.add(new Person("larry", 32));
javaProgramers.add(new Person("jesse", 33));
javaProgramers.add(new Person("mike",65));
javaProgramers.add(new Person("jesse",33));

for(Person item:javaProgramers)
{
System.out.println(item);
}
}
}

三）ListIterator。仅适用于List接口的子类。

public class Hello
{
public static void main(String[] args) throws Exception
{
List<Person> javaProgramers = new ArrayList<Person>();
javaProgramers.add(new Person("aaron",25));
javaProgramers.add(new Person("larry", 32));
javaProgramers.add(new Person("jesse", 33));
javaProgramers.add(new Person("mike",65));
javaProgramers.add(new Person("jesse",33));

ListIterator<Person> iter = javaProgramers.listIterator();
System.out.println("正序输出:");
while(iter.hasNext())
{
System.out.println(iter.next());
}
System.out.println("反序输出:");
while(iter.hasPrevious())
{
System.out.println(iter.previous());
}
}
}

四）Enumeration输出。仅适用于Vector类。

public class Hello
{
public static void main(String[] args) throws Exception
{
Vector<Person> javaProgramers = new Vector<Person>();
javaProgramers.add(new Person("aaron",25));
javaProgramers.add(new Person("larry", 32));
javaProgramers.add(new Person("jesse", 33));
javaProgramers.add(new Person("mike",65));
javaProgramers.add(new Person("jesse",33));

Enumeration<Person> enumeration = javaProgramers.elements();
while(enumeration.hasMoreElements())
{
System.out.println(enumeration.nextElement());
}
}
}