面向对象——多态，抽象类，接口（二）-2-阿里云开发者社区

面向对象——多态，抽象类，接口（二）-2

2024-05-09 10

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简介： 面向对象——多态，抽象类，接口（二）

面向对象——多态，抽象类，接口（二）-1

https://developer.aliyun.com/article/1504154

接口常用实例

4.1 comparable接口

在java中，我们在数组中就学过了Arrays.sort()对一个整数类型的数组进行排序，那么对于在实际处理业务，有些时候排序需要我们指定一个指标进行排序，这个时候就要用到我们java中自带的comparable接口

class Student implements Comparable<Student>{
    public String name;
    public int age;
    public double score;
    //这里的this是谁调用了compareTo方法谁就是
    @Override
    public int compareTo(Student o) {
        //return this.age-o.age;//通过年龄进行比较
        //return (int)(this.score-o.score);//通过分数进行比较
        return this.name.compareTo(o.name);//甚至可以通过名字进行排序
    }
    
    public Student(String name, int age, double score) {
        this.name = name;
        this.age = age;
        this.score = score;
    }
       @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", score=" + score +
                '}';
    }
}
public class demo {
    public static void main(String[] args) {
        Student student=new Student("haha",24,55);
        Student student1=new Student("heihei",20,89);
        System.out.println(student.compareTo(student1));
    }
}

我们甚至可以利用这个接口对更多个数组排序，实现这个接口之后，利用Arrays.sort()进行排序

 public static void main(String[] args) {
        Student[] students =new Student[3];
        students[0]=new Student("zhan",21,98);
        students[1]=new Student("hehe",17,87);
        students[2]=new Student("keke",34,99);
        Arrays.sort(students);
        System.out.println(Arrays.toString(students));
    }

这个类存在一定的缺点，对于类的侵害性大，所以下面我们在介绍comparator接口

4.2 comparator接口

先创立一个学生类

class Student {
    public String name;
    public int age;
    public double score;
    public Student(String name, int age, double score) {
        this.name = name;
        this.age = age;
        this.score = score;
    }
 
    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", score=" + score +
                '}';
    }
}

创立一个年龄比较器

class AgeComparator implements Comparator<Student>{
    @Override
    public int compare(Student o1, Student o2) {
        return o1.age-o2.age;
    }
}

创立一个分数比较器

//成绩比较器
class ScoreComrarator implements Comparator<Student>{
    @Override
    public int compare(Student o1, Student o2) {
        return (int)(o1.score-o2.score);
    }
}

创立一个名字比较器

//名字比较器
class NameComparator implements Comparator<Student>{
    @Override
    public int compare(Student o1, Student o2) {
        return o1.name.compareTo(o2.name);
    }
}

做完上面几步之后，我们基本就可以实现一个（年龄，成绩，名字）来排序

比较分数

public class demo {
    public static void main1(String[] args) {
        Student student=new Student("haha",24,55);
        Student student1=new Student("heihei",20,89);
        ScoreComrarator scoreComrarator=new ScoreComrarator();
        scoreComrarator.compare(student1,student);
    }
}

比较多个数组的一个成绩

public class demo {
    public static void main(String[] args) {
        Student[] students =new Student[3];
        students[0]=new Student("zhan",21,98);
        students[1]=new Student("hehe",17,87);
        students[2]=new Student("keke",34,99);
        ScoreComrarator scoreComrarator=new ScoreComrarator();
        Arrays.sort(students,scoreComrarator);
        System.out.println(Arrays.toString(students));
    }
}

4.3 clonable接口和深拷贝

4.3.1 浅拷贝

class people{
    public int age;
}
public class apple {
    public static void main(String[] args) {
        people people=new people();
        people people1=people;
        System.out.println(people);
        System.out.println(people1);
    }
}

也就是所浅拷贝就是简单来理解就是会有两个引用公用了一个对象。

4.3.2 深拷贝与clonable接口

class people implements Cloneable {
    public int age;
 
    @Override
    protected Object clone() throws CloneNotSupportedException {
        return super.clone();
    }
}
public class apple {
    public static void main(String[] args)throws CloneNotSupportedException {
        people people=new people();
        people people1=(people) people.clone();
        System.out.println(people);
        System.out.println(people1);
    }
}