列表有两个不同的对象需要排序

Question

ArrayList中具有两个不同的类/对象

- Student class has 2 fields --> NAME and ID 

    - Employee class has 2 fields --> NAME and ID 

需要基于ID字段进行排序。能否请你帮助我，谢谢。

我的建议是使用比较器可以帮助我的java代码。

class Emp { 
    String name; 
    int number; 
    public String getName() { return name; } 
    public void setName(String name) { this.name = name; } 
    public int getNumber() { return number; } 
    public void setNumber(int number) { this.number = number; } 
} 

class Student { 
    String name; 
    int number; 
    public String getName() { return name; } 
    public void setName(String name) { this.name = name; } 
    public int getNumber() { return number; } 
    public void setNumber(int number) { this.number = number; } 
} 

class empcomparator implements Comparator { 
    @Override 
    public int compare(Object o1, Object o2) { 
    String a = ((emp) o1).getName(); 
    String b = ((student) o2).getName(); 
    return a.compareTo(b); return 1; 
    } 
} 

主类，我的代码：

Emp emp = new Emp(); 
emp.setName("test1"); 
emp.setNumber(11); 
Student stud= new Student(); 
stud.setName("test2"); 
stud.setNumber(22); 
List<Object> studentlist = new ArrayList<Object>(); 
studentlist.add(emp); 
studentlist.add(stud); 
Collections.sort(studentlist, new empcomparator()); 

列表包含这样需要根据ID进行排序100对象。请给我一个好主意。

Answer 1

使用名称和ID字段创建Person类。

创建Student和Employee类，以便它们继承Person类。

然后你可以制作一个ArrayList<Person>它可以包含这两个元素，你可以使用Comparator<Person>对它进行排序。

修改代码：

abstract class Person implements Comparable<Person> { 
    String name; 
    int number; 
    public Person(final int id, final String name){ 
     setNumber(id); 
     setName(name); 
    } 
    public String getName() { return name; } 
    public void setName(String name) { this.name = name; } 
    public int getNumber() { return number; } 
    public void setNumber(int number) { this.number = number; } 
    public int compareTo(final Person otherPerson){ 
     return Integer.compare(this.getNumber(), otherPerson.getNumber()); 
    } 
    public abstract String toString(); 
} 

class Emp extends Person { 
    public Emp(final int id, final String name){ 
     super(id, name); 
    } 
    public String toString(){ return String.format("Employee: %d, %s", getNumber(), getName()); } 
} 

class Student extends Person { 
    public Student(final int id, final String name){ 
     super(id, name); 
    } 
    public String toString(){ return String.format("Student: %d, %s", getNumber(), getName()); } 
} 

public static void main(final String[] args){ 
    ArrayList<Person> people = new ArrayList<Person>(); 
    people.add(new Student(23, "Bob")); 
    people.add(new Emp(12, "Alice")); 
    people.add(new Student(3, "Carol")); 
    people.add(new Emp(5, "Denise")); 
    System.out.println(people.toString()); 
    Collections.sort(people); 
    System.out.println(people.toString()); 
}