ArrayList中元素排序方法：Collections.sort(list)，

ArrayList中元素排序方法：Collections.sort(list)，

ArrayList中元素排序方法：Collections.sort(list)

package cccc;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

public class SortTest {

	public static void main(final String[] args) {
		final List<String> lists = new ArrayList<String>();
		final List<A> list = new ArrayList<A>();
		final List<B> listB = new ArrayList<B>();
		lists.add("5");
		lists.add("2");
		lists.add("9");
		// lists中的对象String 本身含有compareTo方法，所以可以直接调用sort方法，按自然顺序排序，即升序排序
		Collections.sort(lists);

		final A aa = new A();
		aa.setName("aa");
		aa.setOrder(1);
		final A bb = new A();
		bb.setName("bb");
		bb.setOrder(2);
		list.add(bb);
		list.add(aa);
		// list中的对象A实现Comparable接口
		Collections.sort(list);

		final B ab = new B();
		ab.setName("ab");
		ab.setOrder("1");
		final B ba = new B();
		ba.setName("ba");
		ba.setOrder("2");
		listB.add(ba);
		listB.add(ab);
		// 根据Collections.sort重载方法来实现
		Collections.sort(listB, new Comparator<B>() {

			@Override
			public int compare(final B b1, final B b2) {
				return b1.getOrder().compareTo(b2.getOrder());
			}

		});

		System.out.println(lists);
		System.out.println(list);
		System.out.println(listB);

	}

}

class A implements Comparable<A> {

	private String name;

	private Integer order;

	public String getName() {
		return name;
	}

	public void setName(final String name) {
		this.name = name;
	}

	public Integer getOrder() {
		return order;
	}

	public void setOrder(final Integer order) {
		this.order = order;
	}

	@Override
	public String toString() {
		return "name is " + name + " order is " + order;
	}

	@Override
	public int compareTo(final A a) {
		return order.compareTo(a.getOrder());
	}

}

class B {

	private String name;

	private String order;

	public String getName() {
		return name;
	}

	public void setName(final String name) {
		this.name = name;
	}

	public String getOrder() {
		return order;
	}

	public void setOrder(final String order) {
		this.order = order;
	}

	@Override
	public String toString() {
		return "name is " + name + " order is " + order;
	}
}

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