Java排序(一)如何實現類的排序
阿新 • • 發佈:2020-11-04
類按照類中的某一個屬性(或者多個屬性)來對類的物件進行排序,
有兩種方法可以實現,
1、實現Comparable<T>介面,然後呼叫Collections.sort(List)方法進行排序,
2、不實現Comparable<T>介面,而在排序時使用Collections.sort(List, Comparator<T>)方法,並實現其中的Comparator<T>介面。
以下,實現一個類的排序
public class Student { private String name; private int age; publicStudent() {} public Student(String name, int age) { this.name = name; this.age = age; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } }
一、通過類實現Comparable<T>介面進行排序
public class Student implements Comparable<Student>{ private String name; private int age; public Student() {} public Student(String name, int age) { this.name = name; this.age = age; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } /** * 將物件按姓名字典序升序排序 * @param o * @return */ @Override public int compareTo(Student o) { return this.name.compareTo(o.getName()); } @Override public String toString() { return "Student{" + "name='" + name + '\'' + ", age=" + age + '}'; } }
二、通過在Collections.sort()方法中實現Comparable<T>介面來實現排序
public class Client { public static void main(String[] args){ List<Student> students = new ArrayList<>(); students.add(new Student("a", 18)); students.add(new Student("c", 19)); students.add(new Student("b", 20)); Collections.sort(students, new Comparator<Student>() { @Override public int compare(Student o1, Student o2) { return o1.getAge()>o2.getAge()? -1:(o1.getAge()==o2.getAge()? 0:1); } }); for(Student student:students){ System.out.println(student.toString()); } } }