浅谈TreeSet中的两种排序方式

package exercise1;public class Person implements Comparable{  private int id;  private String name;  public Person(int id, String name) {    super();    this.id = id;    this.name = name;  }  public int getId() {    return id;  }  public void setId(int id) {    this.id = id;  }  public String getName() {    return name;  }  public void setName(String name) {    this.name = name;  }  public String toString() {    return "Person [id=" + id + ", name=" + name + "]";  }  public int hashCode() {    final int prime = 31;    int result = 1;    result = prime * result + id;    result = prime * result + ((name == null) ? 0 : name.hashCode());    return result;  }  public boolean equals(Object obj) {    if (this == obj)      return true;    if (obj == null)      return false;    if (getClass() != obj.getClass())      return false;    Person other = (Person) obj;    if (id != other.id)      return false;    if (name == null) {      if (other.name != null)        return false;    } else if (!name.equals(other.name))      return false;    return true;  }  public int compareTo(Object o) {    if(o instanceof Person){      Person p=(Person)o;      return this.name.compareTo(p.name);    }    return 0;  }  }

package exercise1;//TreeSet下的自然排序和定制排序import java.util.Comparator;import java.util.Iterator;import java.util.Set;import java.util.TreeSet;import java.util.function.Function;import java.util.function.ToDoubleFunction;import java.util.function.ToIntFunction;import java.util.function.ToLongFunction;import org.junit.Test;//定制排序public class DisOrder {  @Test  public void unNature(){    Comparator com=new Comparator() {      public int compare(Object o1, Object o2) {        if(o1 instanceof Person && o2 instanceof Person){          Person p1=(Person)o1;          Person p2=(Person)o2;          return p1.getName().compareTo(p2.getName());        }        return 0;      }          };        Set set=new TreeSet(com);    set.add(new Person(111,"MM"));    set.add(new Person(222,"DD"));    set.add(new Person(333,"GG"));          for(Object obj:set){      System.out.println(obj);    }  }  //自然排序  @Test  public void nature() {    Set set=new TreeSet();    set.add("aa");    set.add("bb");    set.add("ff");    set.add("zz");    for(Object obj:set){      System.out.println(obj);    }                }}