【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+"
";
    }
}
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+"
";
    }
}
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
]

---

如果需要对一组对象进行排序建议优先使用Comparable