【java】实现Interface java.lang.Comparable<T>接口的int compareTo(T o)方法实现对象数组或链表或集合的排序，和挽救式对象比较器Interface java.util.Comparator<T>

 package 对象比较排序;

 import java.util.Arrays;

 class A implements Comparable<A>{
     private String name;
     private int age;
     public A(String name,int age){
         this.name=name;
         this.age=age;
     }
     @Override
     public int compareTo(A o) {//此方法无需手工调用，Arrays会自动调用
         if(this.age<o.age)
             return -1;//1.this小于返回负数，this大于返回正数，则升序；
         if(this.age>o.age)
             return 1;//2.this小于返回正数，this大于返回负数，则降序；
         return 0;//相等返回0
     }
     @Override
     public String toString() {
         return "name="+name+",age="+age+"\n";
     }
 }
 public class TestComparable {
     public static void main(String[] args) {
         A[] as=new A[]{
                     new A("张三",63),
                     new A("李四",33),
                     new A("王五",53),
                     new A("赵六",43),
                 };
         Arrays.sort(as);
         System.out.println(Arrays.toString(as));
     }
 }

运行结果：

[name=李四,age=33
, name=赵六,age=43
, name=王五,age=53
, name=张三,age=63
]

---

 package 对象比较排序;

 import java.util.Arrays;
 import java.util.Comparator;

 class B{
     private String name;
     private int age;
     public B(String name,int age){
         this.name=name;
         this.age=age;
     }
     public int getAge() {
         return age;
     }
     @Override
     public String toString() {
         return "name="+name+",age="+age+"\n";
     }
 }
 class BComparator implements Comparator<B>{
     @Override
     public int compare(B o1, B o2) {
         if(o1.getAge()<o2.getAge())
             return -1;
         if(o1.getAge()>o2.getAge())
             return 1;
         return 0;
     }
 }
 public class TestComparator {
     public static void main(String[] args) {
         B[] bs=new B[]{new B("张三",44),
                 new B("李四",33),
                 new B("王二",55),
                 new B("赵六",66)};
         BComparator bc=new BComparator();
         Arrays.sort(bs, bc);
         System.out.println(Arrays.toString(bs));
     }
 }

运行结果：

[name=李四,age=33
, name=张三,age=44
, name=王二,age=55
, name=赵六,age=66
]

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如果需要对一组对象进行排序建议优先使用Comparable