代码

public class Complex {
    private double x,y;
    public Complex(double real,double imaginary){
        x=real;
        y=imaginary;
    }
    public String toString(){
        return "("+x+","+y+"i)";
    }
    public Complex add(Complex a){
        return new Complex(x+a.x,y+a.y);
    }
    public Complex add(double x,double y){
        return new Complex(this.x+x,this.y+y);
    }
    public static Complex add(Complex a1,Complex a2){
        return new Complex(a1.x+a2.x,a1.y+a2.y);
    }
    public Complex multiply(Complex a){
        double X1=this.x*a.x-this.y*a.y;
        Double Y1=this.x*a.y+this.y*a.x;
        return new Complex(X1,Y1);
    }
    public Complex multiply(double x,double y){
        double X1=this.x*x-this.y*y;
        Double Y1=this.x*y+this.y*x;
        return new Complex(X1,Y1);
    }
    public static Complex multiply(Complex a,Complex b){
        double X1=a.x*b.x-a.y*b.y;
        Double Y1=a.x*b.y+a.y*b.x;
        return new Complex(X1,Y1);
    }
    public double ABC(){
        return Math.sqrt(this.x*this.x+this.y+this.y);
    }
    public static void main(String[] args) {
        Complex x,y,z;
        x=new Complex(4,5);
        y=new Complex(3.4,2.8);
        System.out.println("加法：");
        z=add(x,y);
        System.out.println("resulu1="+z);
        z=x.add(y);
        System.out.println("resulu2="+z);
        z=x.add(6,8);
        System.out.println("resulu3="+z);
        System.out.println("乘法：");
        Complex y1=new Complex(1,2);
        System.out.println("multiply(Complex a):"+x.multiply(y1));
        System.out.println("multiply(double x,double y):"+x.multiply(1.0,2.0));
        System.out.println("static Complex multiply(Complex a,Complex b):"+multiply(x,y1));
        System.out.printf("x的模长为：%.4f",x.ABC());
    }
}

public class Person {
    String name;
    String sex;
    int age;
    public Person(String name,String sex,int age){
        this.name=name;
        this.sex=sex;
        this.age=age;
    }
    public String toString(){
        return "姓名："+name+" 性别："+sex+" 年龄："+age;
    }
    public static void main(String[] args) {
        Person P=new Person("张三","男",18);
        System.out.println(P);
        Teacher PT=new Teacher("张三","男",18,"教授","计算机");
        System.out.println(PT);
        Student PS=new Student("张三","男",18,4845148,"2020/9/30","计算机");
        System.out.println(PS);
    }
}
class Teacher extends Person{
    String Zhicheng;
    String department;
    public Teacher(String name,String sex,int age, String Zhicheng,String department){
        super(name,sex,age);
        this.Zhicheng=Zhicheng;
        this.department=department;
    }
    public String toString(){
        return "姓名："+name+" 性别："+sex+" 年龄："+age+" 职称："+Zhicheng+" 部门："+department;
    }
}
class Student extends Person{
    int Num;
    String ctime;
    String specialized;
    public Student(String name,String sex,int age,int Num,String ctime, String specialized){
        super(name,sex,age);
        this.Num=Num;
        this.ctime=ctime;
        this.specialized=specialized;
    }
    public String toString(){
        return "姓名："+name+" 性别："+sex+" 年龄："+age+" 学号："+Num+" 入学时间："+ctime+" 专业："+specialized;
    }
}

public class Point {
    public int x;
    public int y;
    public Point(int a,int b){
        this.x=a;
        this.y=b;
    }    //构造函数
    public double distance(Point P){
        return Math.sqrt(((this.x-P.x)*(this.x-P.x)+(this.y-P.y)*(this.y-P.y)));
    }
    public double distance(int X1,int Y1){
        double d=(this.x-X1)*(this.x-X1)+(this.y-Y1)*(this.y-Y1);
       //System.out.println(d);
        d=Math.sqrt(d);
        return d;
    }
    public static double distance(Point X,Point Y){
        double d=(double)(X.x-Y.x)*(X.x-Y.x)+(X.y-Y.y)*(X.y-Y.y);
        d=Math.sqrt(d);
        //System.out.println(X.x);
        return d;
    }
    public static void main(String[] args) {
        Point P1=new Point(4,5);
        Point P2=new Point(9,10);
        System.out.printf("distance(Point P):d=%.4f\n",P1.distance(P2));
        System.out.printf("distance(int x,int y):d=%.4f\n",P1.distance(9,10));
        System.out.printf("distance(Point X,Point Y):d=%.4f\n",distance(P1,P2));
    }
}