Java中Collections的sort方法和Comparable与Comparator的比较
一、Comparable
新建Student1类，类实现Comparable接口，并重写compareTo方法
public class Student1 implements Comparable<Student1> { private String name; private int age;
public Student1() {
} public Student1(String name, int age) { this.name = name; this.age = age;
} public String getName() { return name;
} public void setName(String name) { this.name = name;
} public Integer getAge() { return age;
} public void setAge(Integer age) { this.age = age;
}
@Override public int compareTo(Student1 s) { int num = this.age - s.age;
int num1 = (num == 0 ? this.name.compareTo(s.name) : num); return num1;
}
}调用
import java.util.ArrayList;import java.util.Collections;import java.util.List;public class Student1Test {
public static void main(String[] args) {
List<Student1> list1 = new ArrayList<Student1>();
list1.add(new Student1("林青霞", 27));
list1.add(new Student1("风清扬", 30));
list1.add(new Student1("刘晓曲", 28));
list1.add(new Student1("武鑫", 29));
list1.add(new Student1("林青霞", 27));
Collections.sort(list1); for (Student1 s : list1) {
System.out.println(s.getName() + "---" + s.getAge());
}
}
}二、Comparator
新建Student2类
public class Student2 { private String name; private int age; public Student2() {
} public Student2(String name, int age) { this.name = name; this.age = age;
} public String getName() { return name;
} public void setName(String name) { this.name = name;
} public Integer getAge() { return age;
} public void setAge(Integer age) { this.age = age;
}
}调用
import java.util.ArrayList;import java.util.Collections;import java.util.Comparator;import java.util.
List;public class Student2Test { public static void main(String[] args) {
List<Student2> list2 = new ArrayList<Student2>();
list2.add(new Student2("林青霞", 27));
list2.add(new Student2("风清扬", 30));
list2.add(new Student2("刘晓曲", 28));
list2.add(new Student2("武鑫", 29));
list2.add(new Student2("林青霞", 27));
//方式一
Collections.sort(list2, new MyComparator()); for (Student2 s : list2) {
System.out.println(s.getName() + "---" + s.getAge());
}
//逆序
//方式二：匿名类
Collections.sort(list2, new Comparator<Student2>() {
@Override public int compare(Student2 s1, Student2 s2) {
int num = s2.getAge() - s1.getAge();
int num1 = (num == 0 ? s2.getName().compareTo(s1.getName())
: num); return num1;
}
}); for (Student2 s : list2) {
System.out.println(s.getName() + "---" + s.getAge());
}
}
}class MyComparator implements Comparator<Student2> {
@Override public int compare(Student2 s1, Student2 s2) {
int num = s1.getAge() - s2.getAge();
int num1 = (num == 0 ? s1.getName().compareTo(s2.getName()) : num); return num1;
}
}