Java 基础类和对象

class BirthDate {
    private int day;
    private int month;
    private int year;


    BirthDate(int d, int m, int y) {
        day = d;
        month = m;
        year = y;
    }

    public void setDay(int d) {
        day = d;
      }

    public void setMonth(int m) {
        month = m;
    }

    public void setYear(int y) {
        year = y;
    }

    public int getDay() {
        return day;
    }

    public int getMonth() {
        return month;
    }

    public int getYear() {
        return year;
    }

    public void display() {
        System.out.println
        (day + " - " + month + " - " + year);
    }
}


public class Test{
    public static void main(String args[]){
        Test test = new Test();
        int date = 9;
        BirthDate d1= new BirthDate(7,7,1970);
        BirthDate d2= new BirthDate(1,1,2000);
        test.change1(date);
        test.change2(d1);
        test.change3(d2);
        System.out.println("date=" + date);
        d1.display();
        d2.display();
    }

    public void change1(int i){
        i = 1234;
    }

    public void change2(BirthDate b) {
        b = new BirthDate(22,2,2004);
    }

    public void change3(BirthDate b) {
        b.setDay(22);
    }
}

class Point {
    double x, y, z;

    Point(double _x, double _y, double _z) {
        x = _x;
        y = _y;
        z = _z;
    }

    void setX(double _x) {
        x = _x;
    }

    double getDistance(Point p) {
        return (x - p.x)*(x - p.x) + (y - p.y)*(y - p.y) + (z - p.z)*(z - p.z);
    }

}

public class TestPoint {
    public static void main(String[] args) {
        Point p = new Point(1.0, 2.0, 3.0);
        Point p1 = new Point(0.0, 0.0, 0.0);
        System.out.println(p.getDistance(p1));

        p.setX(5.0);
        System.out.println(p.getDistance(new Point(1.0, 1.0, 1.0)));
    }
}

课件： Java 基础类和对象.pdf