Comparable

Test.java

List<Student> list=new ArrayList<Student>();
        list.add(s1);
        list.add(s2);
        list.add(s3);
        Collections.sort(list);//单一类中的比较，实现comparable接口（如果没有实现这个接口的话，这个sort方法是不能用的，会报类转换异常），重写compareTo方法，自定义比较规则
        Collections.sort(list, new MyComparator());//多个类间的比较，MyComparator类实现comparator接口（同上），重写compare方法，自定义比较规则
        for(int i=0;i<list.size();i++){
            System.out.println(list.get(i).toString());
        }

Student.java

public class Student implements Comparable{
    private String name;
    private String school;


    public Student() {
        super();
    }


    public Student(String name, String school) {
        super();
        this.name = name;
        this.school = school;
    }


    public String getName() {
        return name;
    }


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


    public String getSchool() {
        return school;
    }


    public void setSchool(String school) {
        this.school = school;
    }


    @Override
    public String toString() {
        return name+"毕业于:"+school;
    }


    @Override
    public int compareTo(Object arg0) {
        Student s=(Student) arg0;
        int result=0;
        result=this.getName().compareTo(s.getName());
        if(result==0){
            result=this.getSchool().compareTo(s.getName());
        }
        return result;
    }

MyComparator.java

public class MyComparator implements Comparator {


    @Override
    public int compare(Object o1, Object o2) {
        Student s1=(Student) o1;
        Student s2=(Student) o2;
        int result=0;
        result=s1.getName().compareTo(s2.getName());//String类封装类，默认有comparableTo方法，直接用即可
        if(result==0){
            result=s1.getSchool().compareTo(s2.getSchool());
        }
        return result;
    }


}