关于 Java Collections API 您不知道的 5 件事，第 2部分 - 黑马程序员技术交流社区

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// Person.java
import java.util.*;
public class Person
implements Iterable<Person>
{
public Person(String fn, String ln, int a, Person... kids)
{
this.firstName = fn; this.lastName = ln; this.age = a;
for (Person child : kids)
children.add(child);
}
public String getFirstName() { return this.firstName; }
public String getLastName() { return this.lastName; }
public int getAge() { return this.age; }
public Iterator<Person> iterator() { return children.iterator(); }
public void setFirstName(String value) { this.firstName = value; }
public void setLastName(String value) { this.lastName = value; }
public void setAge(int value) { this.age = value; }
public String toString() {
return "[Person: " +
"firstName=" + firstName + " " +
"lastName=" + lastName + " " +
"age=" + age + "]";
}
private String firstName;
private String lastName;
private int age;
private List<Person> children = new ArrayList<Person>();
}
// App.java
public class App
{
public static void main(String[] args)
{
Person ted = new Person("Ted", "Neward", 39,
new Person("Michael", "Neward", 16），
new Person("Matthew", "Neward", 10));
// Iterate over the kids
for (Person kid : ted)
{
System.out.println(kid.getFirstName());
}
}
}

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public class ReverseIterator
{
public static void main(String[] args)
{
Person ted = new Person("Ted", "Neward", 39,
new Person("Michael", "Neward", 16），
new Person("Matthew", "Neward", 10));
// Make a copy of the List
List<Person> kids = new ArrayList<Person>(ted.getChildren());
// Reverse it
Collections.reverse(kids);
// Display it
System.out.println(kids);
}
}

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class MyCollections
{
public static <T> List<T> reverse(List<T> src)
{
List<T> results = new ArrayList<T>(src);
Collections.reverse(results);
return results;
}
}

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public interface SortedCollection<E> extends Collection<E>
{
public Comparator<E> getComparator();
public void setComparator(Comparator<E> comp);
}

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import java.util.*;
public class ArraySortedCollection<E>
implements SortedCollection<E>, Iterable<E>
{
private Comparator<E> comparator;
private ArrayList<E> list;
public ArraySortedCollection(Comparator<E> c)
{
this.list = new ArrayList<E>();
this.comparator = c;
}
public ArraySortedCollection(Collection<? extends E> src, Comparator<E> c)
{
this.list = new ArrayList<E>(src);
this.comparator = c;
sortThis();
}
public Comparator<E> getComparator() { return comparator; }
public void setComparator(Comparator<E> cmp) { comparator = cmp; sortThis(); }
public boolean add(E e)
{ boolean r = list.add(e); sortThis(); return r; }
public boolean addAll(Collection<? extends E> ec)
{ boolean r = list.addAll(ec); sortThis(); return r; }
public boolean remove(Object o)
{ boolean r = list.remove(o); sortThis(); return r; }
public boolean removeAll(Collection<?> c)
{ boolean r = list.removeAll(c); sortThis(); return r; }
public boolean retainAll(Collection<?> ec)
{ boolean r = list.retainAll(ec); sortThis(); return r; }
public void clear() { list.clear(); }
public boolean contains(Object o) { return list.contains(o); }
public boolean containsAll(Collection <?> c) { return list.containsAll(c); }
public boolean isEmpty() { return list.isEmpty(); }
public Iterator<E> iterator() { return list.iterator(); }
public int size() { return list.size(); }
public Object[] toArray() { return list.toArray(); }
public <T> T[] toArray(T[] a) { return list.toArray(a); }
public boolean equals(Object o)
{
if (o == this)
return true;
if (o instanceof ArraySortedCollection)
{
ArraySortedCollection<E> rhs = (ArraySortedCollection<E>)o;
return this.list.equals(rhs.list);
}
return false;
}
public int hashCode()
{
return list.hashCode();
}
public String toString()
{
return list.toString();
}
private void sortThis()
{
Collections.sort(list, comparator);
}
}

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