Question

有Person类的对象，如：M1，M2，M3，M4，M5，W1，W2，W3，W4，C1，C2。 M：Man，W：Woman，C：Child

它们存储在下面的数组中：

Person[] arr = {M1,M3,C1,W1,W3,M2,M4,W2,C2,W4,M5};

现在必须根据为每种类型的对象设置的优先级重新排列数组。优先权在Enum中给出：

enum Priority{
    One,
    Two,
    Three;
}

同时确保订单保持不变，例如：M1应该在M2之前，M2应该在M3之前，依此类推......

输入： Person[] arr = {M1,M3,C1,W1,W3,M2,M4,W2,C2,W4,M5}; 人的优先权：优先权。二女性优先：Priority.One 儿童优先：优先。三

预期输出： Person[] arr = {W1,W2,W3,W4,M1,M2,M3,M4,M5,C1,C2};

输出错误： Person[] arr = {W1,W3,W2,W4,M1,M5,M4,M3,M2,C2,C1};

后者是错误的，因为订单也必须保持不变。

Answer 1

尝试以下

    final List<Person> persons = new ArrayList<>();
    IntStream.rangeClosed(1, 5).mapToObj(i -> new Person("M" + i, Priority.TWO)).forEach(persons::add);
    IntStream.rangeClosed(1, 4).mapToObj(i -> new Person("W" + i, Priority.ONE)).forEach(persons::add);
    IntStream.rangeClosed(1, 2).mapToObj(i -> new Person("C" + i, Priority.THREE)).forEach(persons::add);
    persons.add(new Person("M11", Priority.TWO)); // test to sort by number
    List<Person> sorted = persons.stream()
            .sorted(Comparator.comparing(Person::getPriority).thenComparingInt(p -> Integer.parseInt(p.getName().substring(1))))
            .collect(Collectors.toList());
    System.out.println("Before sort " + persons.stream().map(Person::getName).collect(Collectors.toList()));
    System.out.println("After sort " + sorted.stream().map(Person::getName).collect(Collectors.toList()));

输出中

Before sort [M1, M2, M3, M4, M5, W1, W2, W3, W4, C1, C2, M11]
After sort [W1, W2, W3, W4, M1, M2, M3, M4, M5, M11, C1, C2]

请注意：枚举中的值是有序的，上面的代码取决于枚举类中值的顺序

修改-1

Compartor

Comparator<Person> comp = new Comparator<Person>() { @Override public int compare(Person p1, Person p2) { int co = p1.getPriority().compareTo(p2.getPriority()); if (co == 0) return Integer.parseInt(p1.getName().substring(1)) - Integer.parseInt(p2.getName().substring(1)); return co; } };

Answer 2

我相信你必须为Person Class创建自己的比较器，这样你的Person对象可以使用Collections.sort（）方法在集合中进行排序。

这是一个如何为类创建自己的比较器的链接 http://www.tutorialspoint.com/java/java_using_comparator.htm

Answer 3

以下是使用Comparator界面对自定义对象进行排序的解决方案。

import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

public class Person {

private int priority;
private String objName;

Person(String name,int value){
    this.objName = name;
    this.priority = value;
}

public int getPriority() {
    return priority;
}

public void setPriority(int priority) {
    this.priority = priority;
}

public String getObjName() {
    return objName;
}

public void setObjName(String objName) {
    this.objName = objName;
}   

public static void main(String[] args) {
    Person M1 = new Person("M1",Priority.valueOf("ONE").getValue());
    Person M2 = new Person("M2",Priority.valueOf("ONE").getValue());
    Person M3 = new Person("M3",Priority.valueOf("ONE").getValue());
    Person M4 = new Person("M4",Priority.valueOf("ONE").getValue());
    Person M5 = new Person("M5",Priority.valueOf("ONE").getValue());
    Person W1 = new Person("W1",Priority.valueOf("THREE").getValue());
    Person W2 = new Person("W2",Priority.valueOf("THREE").getValue());
    Person W3 = new Person("W3",Priority.valueOf("THREE").getValue());
    Person W4 = new Person("W4",Priority.valueOf("THREE").getValue());      
    Person C1 = new Person("C1",Priority.valueOf("TWO").getValue());
    Person C2 = new Person("C2",Priority.valueOf("TWO").getValue());

    Person[] arr = {M1,M3,C1,W1,W3,M2,M4,W2,C2,W4,M5};

    List<Person> list = Arrays.asList(arr);

    System.out.println("Before sort...");
    for(Person p : list){
        System.out.println(p.getObjName());
    }

    Collections.sort(list, new PersonComparator<Person>());

    System.out.println("After sort...");
    for(Person p : list){
        System.out.println(p.getObjName());
    }
}

}

enum Priority{  
ONE(1),TWO(2),THREE(3); 

private int value;  
public int getValue() {
    return value;
}   
Priority(int v){
    this.value = v;
}
}

class PersonComparator<T> implements Comparator<Person> {
public int compare(Person p1, Person p2) {
    //Sorting based on priority
    int v1 = p1.getPriority();
    int v2 = p2.getPriority();
    ;
    if (v1 - v2 == 0) {
        //Sorting based on object name
        int i1 = Integer.parseInt(p1.getObjName().substring(1, 2));
        int i2 = Integer.parseInt(p2.getObjName().substring(1, 2));
        return i1 - i2;
    }
    return v1 - v2;
}
}

根据优先级重新排列阵列

3 个答案: