Collections Comparable 内部定义实现排序

在上一篇文章中,介绍了Comparable 和 Comparator排序的不同,还具体实现了Comparator排序的方法,在这里,简单实现Comparable接口完成的排序,数据同上一篇,只是具体实现的方法改变了.

DataBean.java

package com.baomw;

import java.io.Serializable;
import java.text.MessageFormat;

public class DataBean implements Serializable,Comparable<DataBean>{

	private static final long serialVersionUID = 1L;

	private long id;
	private String name;
	private String sex;

	public DataBean() {

	}

	public DataBean(long id, String name, String sex) {
		this.id = id;
		this.name = name;
		this.sex = sex;
	}

	public long getId() {
		return id;
	}

	public void setId(long id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

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

	public String getSex() {
		return sex;
	}

	public void setSex(String sex) {
		this.sex = sex;
	}

	@Override
	public String toString() {
		return MessageFormat.format("id:{0},name:{1},sex:{2}", this.id,
				this.name, this.sex);
	}

	@Override
	public int compareTo(DataBean o) {
		return this.name.compareTo(o.getName());
	}
}

说明:需要在类内部实现Comparable接口,并实现该接口的compareTo的方法.在这里使用的String中已经实现的compareTo的方法,按字母进行排序.

RunDemoMain.java

package com.baomw;

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

public class RunDemoMain {

	public static void main(String[] args) {
		List<DataBean> dataBeans = new ArrayList<DataBean>();
		dataBeans.add(new DataBean(23, "b", "w"));
		dataBeans.add(new DataBean(34, "e", "w"));
		dataBeans.add(new DataBean(12, "s", "w"));
		dataBeans.add(new DataBean(10, "c", "w"));
		dataBeans.add(new DataBean(19, "g", "w"));
		dataBeans.add(new DataBean(78, "a", "w"));
		dataBeans.add(new DataBean(66, "w", "w"));
		dataBeans.add(new DataBean(50, "r", "w"));

		System.out.println("==========排序前==========");
		for (DataBean bean : dataBeans) {
			System.out.println(bean);
		}

		System.out.println("==========排序后==========");
		Collections.sort(dataBeans);
		
		for (DataBean bean : dataBeans) {
			System.out.println(bean);
		}
	}
}

运行后显示:

==========排序前==========
id:23,name:b,sex:w
id:34,name:e,sex:w
id:12,name:s,sex:w
id:10,name:c,sex:w
id:19,name:g,sex:w
id:78,name:a,sex:w
id:66,name:w,sex:w
id:50,name:r,sex:w
==========排序后==========
id:78,name:a,sex:w
id:23,name:b,sex:w
id:10,name:c,sex:w
id:34,name:e,sex:w
id:19,name:g,sex:w
id:50,name:r,sex:w
id:12,name:s,sex:w
id:66,name:w,sex:w