Guava:Ordering对象多属性排序

• Person多字段排序结果

针对Person对象，根据年龄升序，字段为空放最前面，再根据名称进行升序，空字符放最后面，最后根据排序字段进行升序排序。

import com.google.common.base.Function;
import com.google.common.collect.Lists;
import com.google.common.collect.Ordering;
import lombok.Data;
import lombok.ToString;

import java.io.Serializable;
import java.util.List;

public class TestGuava {
    public static void main(String[] args) {
        List persons = Lists.newArrayListWithExpectedSize(4);
        persons.add(new Person(11, "libai",(short)1));
        persons.add(new Person(99, "wangwu",(short)2));
        persons.add(new Person(null, "zhangsan",(short)8));
        persons.add(new Person(15, "aba",(short)8));
        persons.add(new Person(15, "aba",(short)9));
        persons.add(new Person(15, "jim",(short)7));
        persons.add(new Person(15, "wan",null));
        System.out.println("正常排序=====");
        persons.forEach(System.out::println);

        Ordering orderAge = Ordering.natural().nullsFirst().onResultOf(new Function() {
            @Override
            public Integer apply(Person person) {
                return person.getAge();
            }
        });
        Ordering orderName = Ordering.natural().nullsLast().onResultOf(new Function() {
            @Override
            public String apply(Person person) {
                return person.getName();
            }
        });
        Ordering orderOrderNo = Ordering.natural().nullsLast().onResultOf(new Function() {
            @Override
            public Short apply(Person person) {
                return person.getOrderNo();
            }
        });
        List mutilResult = Ordering.from(orderAge).compound(orderName).compound(orderOrderNo).sortedCopy(persons);
        System.out.println("多字段排序结果:按照年龄，排序，名称排序");
        mutilResult.forEach(System.out::println);


    }

}


@Data
@ToString
class Person implements Serializable {
    private Integer age;

    private String name;

    private Short orderNo;

    public Person(Integer age, String name) {
        this.age = age;
        this.name = name;
    }

    public Person(Integer age, String name, Short orderNo) {
        this.age = age;
        this.name = name;
        this.orderNo = orderNo;
    }
}