在“实验4”包中编写“实验2Point”和“实验 2Circle”类的子类“实验4Point” “实验 4.Circle”，并重写其构造方法、equals0方法和 toString0)方法; (2)在实验4”包中编写测试类实验4.Test，并测试上述方法的正确性。●

好的，根据您的要求，我提供以下Java代码示例：

实验2Point类：

public class 实验2Point {
    private int x;
    private int y;

    public 实验2Point(int x, int y) {
        this.x = x;
        this.y = y;
    }

    // getters and setters
    public int getX() {
        return x;
    }

    public void setX(int x) {
        this.x = x;
    }

    public int getY() {
        return y;
    }

    public void setY(int y) {
        this.y = y;
    }

    @Override
    public boolean equals(Object obj) {
        if (obj instanceof 实验2Point) {
            实验2Point other = (实验2Point) obj;
            return x == other.x && y == other.y;
        }
        return false;
    }

    @Override
    public String toString() {
        return "(" + x + ", " + y + ")";
    }
}

实验2Circle类：

public class 实验2Circle {
    private 实验2Point center;
    private double radius;

    public 实验2Circle(实验2Point center, double radius) {
        this.center = center;
        this.radius = radius;
    }

    // getters and setters
    public 实验2Point getCenter() {
        return center;
    }

    public void setCenter(实验2Point center) {
        this.center = center;
    }

    public double getRadius() {
        return radius;
    }

    public void setRadius(double radius) {
        this.radius = radius;
    }

    @Override
    public boolean equals(Object obj) {
        if (obj instanceof 实验2Circle) {
            实验2Circle other = (实验2Circle) obj;
            return center.equals(other.center) && radius == other.radius;
        }
        return false;
    }

    @Override
    public String toString() {
        return "Circle with center " + center.toString() + " and radius " + radius;
    }
}

实验4Point类：

public class 实验4Point extends 实验2Point {
    public 实验4Point(int x, int y) {
        super(x, y);
    }

    @Override
    public boolean equals(Object obj) {
        if (obj instanceof 实验4Point) {
            实验4Point other = (实验4Point) obj;
            return getX() == other.getX() && getY() == other.getY();
        }
        return false;
    }

    @Override
    public String toString() {
        return "实验4Point" + super.toString();
    }
}

实验4Circle类：

public class 实验4Circle extends 实验2Circle {
    public 实验4Circle(实验4Point center, double radius) {
        super(center, radius);
    }

    @Override
    public boolean equals(Object obj) {
        if (obj instanceof 实验4Circle) {
            实验4Circle other = (实验4Circle) obj;
            return getCenter().equals(other.getCenter()) && getRadius() == other.getRadius();
        }
        return false;
    }

    @Override
    public String toString() {
        return "实验4Circle with center " + getCenter().toString() + " and radius " + getRadius();
    }
}

实验4.Test测试类：

public class 实验4Test {
    public static void main(String[] args) {
        实验2Point p1 = new 实验2Point(1, 2);
        实验2Point p2 = new 实验2Point(1, 2);
        System.out.println(p1.equals(p2)); // expected output: true
        System.out.println(p1.toString()); // expected output: (1, 2)

        实验4Point p3 = new 实验4Point(1, 2);
        实验4Point p4 = new 实验4Point(1, 2);
        System.out.println(p3.equals(p4)); // expected output: true
        System.out.println(p3.toString()); // expected output: 实验4Point(1, 2)

        实验2Circle c1 = new 实验2Circle(new 实验2Point(1, 2), 3);
        实验2Circle c2 = new 实验2Circle(new 实验2Point(1, 2), 3);
        System.out.println(c1.equals(c2)); // expected output: true
        System.out.println(c1.toString()); // expected output: Circle with center (1, 2) and radius 3.0

        实验4Point center = new 实验4Point(1, 2);
        实验4Circle c3 = new 实验4Circle(center, 3);
        实验4Circle c4 = new 实验4Circle(center, 3);
        System.out.println(c3.equals(c4)); // expected output: true
        System.out.println(c3.toString()); // expected output: 实验4Circle with center 实验4Point(1, 2) and radius 3.0
    }
}