TreeSet排序，存储自定义对象，自定义比较器示例

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在集合初始化时，就有了比较方式。

示例：需求：
往TreeSet集合中存储自定义对象学生，按照学生的年龄进行排序。

package tan;
import java.util.Iterator;
import java.util.TreeSet;
public class TreeSetDemo {
	public static void main(String[] args) {
		TreeSet ts=new TreeSet();
				ts.add(new Student("tan1", 21));
				ts.add(new Student("tan3", 20));
				ts.add(new Student("tan2", 23));
				ts.add(new Student("tan5", 21));
				
				Iterator it=ts.iterator();
				while(it.hasNext()){
				System.out.println(it.next());
				}
	}
}
class Student implements Comparable{
	private String name;
	private Integer age;
	
	public Student(String name, int age) {
		this.name = name;
		this.age = age;
	}

	public String getName() {
		return name;
	}

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

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}
	@Override
	public String toString() {
		
		return "name:"+this.name+" "+"age:"+this.age;
	}
	@Override
	public int compareTo(Object obj) {
		if(!(obj instanceof Student))throw new RuntimeException("非学生对象");
		Student s=(Student)obj;
		if(this.age>s.age) return 1;
		//排序时，当主要条件相同时，一定判断一下次要条件。
		if(this.age==s.age)
		{
			return this.name.compareTo(s.name);
		}
		return -1;
	}
	
}

package tan;
import java.util.Comparator;
import java.util.Iterator;
import java.util.TreeSet;
public class TreeSetDemo {
	public static void main(String[] args) {
		//在这里面可以传入自定义比较器
		TreeSet ts=new TreeSet(new StudentAgeComparator());
		
				ts.add(new Student("tan01", 21));
				ts.add(new Student("tan03", 20));
				ts.add(new Student("tan03", 22));
				ts.add(new Student("tan0012", 23));
				ts.add(new Student("tan007", 21));
				
				Iterator it=ts.iterator();
				while(it.hasNext()){
				System.out.println(it.next());
				}
	}
}
class Student implements Comparable{
	private String name;
	private Integer age;
	
	public Student(String name, int age) {
		this.name = name;
		this.age = age;
	}

	public String getName() {
		return name;
	}

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

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}
	@Override
	public String toString() {
		
		return "name:"+this.name+" "+"age:"+this.age;
	}
	@Override
	public int compareTo(Object obj) {
		if(!(obj instanceof Student))throw new RuntimeException("非学生对象");
		Student s=(Student)obj;
		if(this.age>s.age) return 1;
		//排序时，当主要条件相同时，一定判断一下次要条件。
		if(this.age==s.age)
		{
			return this.name.compareTo(s.name);
		}
		return -1;
	}
	
}
//自定义姓名比较器
class StudentNameComparator implements Comparator{

	@Override
	public int compare(Object o1, Object o2) {
		Student s1=(Student)o1;
		Student s2=(Student)o2;
		int num=s1.getName().compareTo(s2.getName());
		if(num==0){
			//因为Ingteger已经实现了comparable接口
			return new Integer(s1.getAge()).compareTo(new Integer(s2.getAge()));
			//也可以这样写
			/*
			if(s1.getAge()>s2.getAge())
				return 1;
			if(s1.getAge()==s2.getAge())
				return 0;
			return -1;
			*/
		}
		return num;
	}
	
}
//自定义年龄比较器
class StudentAgeComparator implements Comparator<Student>{

	@Override
	public int compare(Student o1, Student o2) {
		int i=o1.getAge()-o2.getAge();
		return i;
	}	
}

package tan;
import java.util.*;
public class TreeSetTest {
	public static void main(String[] args) {
		TreeSet ts = new TreeSet(new StrLengthComparator());

		ts.add("abcd");
		ts.add("cc");
		ts.add("cba");
		ts.add("aaa");
		ts.add("z");
		ts.add("hahaha");

		Iterator it = ts.iterator();

		while (it.hasNext()) {
			System.out.println(it.next());
		}
	}
}

class StrLengthComparator implements Comparator {
	@Override
	public int compare(Object o1, Object o2) {
		String s1 = (String) o1;
		String s2 = (String) o2;
		int num = new Integer(s1.length()).compareTo(new Integer(s2.length()));
		//当第一条件满足时，判断第二个条件按照自然顺序排序
		if(num==0){
			return s1.compareTo(s2);
		}
		return num;
	}
}

TreeSet排序，存储自定义对象，自定义比较器示例,布布扣,bubuko.com

TreeSet排序，存储自定义对象，自定义比较器示例

标签：style   java   color   使用   strong   os   

原文地址：http://blog.csdn.net/u010834071/article/details/37990491