2022年09月23日Java上机

示例3-2

JBT3202

class A_JBT3202 {
    int x, y;
    float z;

    double add(double f1, double f2) {
        return f1 + f2;
    }

    int add(int i1, int i2) {
        return i1 + i2;
    }
}

public class JBT3202 {
    public static void main(String args[]) {
        A_JBT3202 a = new A_JBT3202();
        System.out.println("浮点数相加=" + a.add(1.1, 2.2));
        System.out.println("整数相加=" + a.add(1, 2));
    }
}

示例3-3

JBT3301

class A_JBT3301 {
    int x;
    int y;

    void set(int x, int y) {
        this.x = x;
        this.y = y;
    }

    int getx() {
        return x;
    }

    int gety() {
        return y;
    }

    int add() {
        return (x + y);
    }
}

public class JBT3301 {
    public static void main(String args[]) {
        //创建对象方式1
        A_JBT3301 a1;
        a1 = new A_JBT3301();
        a1.set(1, 2);
        System.out.println(a1.x + "+" + a1.y + "=" + a1.add());
        System.out.println(a1.getx() + "+" + a1.gety() + "=" + a1.add());
        //创建对象方式2
        A_JBT3301 a2 = new A_JBT3301();
        a2.set(3, 4);
        System.out.println(a2.x + "+" + a2.y + "=" + a2.add());
        System.out.println(a2.getx() + "+" + a2.gety() + "=" + a2.add());
        a1 = null;
        a2 = null;
    }
}

示例3-7

class A {
    static int x;
    int y;

    void setx(int x0) {
        x = x0;
    }

    void sety(int y0) {
        y = y0;
    }

    void showx() {
        System.out.println("x=" + x);
    }

    void showy() {
        System.out.println("y=" + y);
    }
}

public class JBT3404 {
    public static void main(String args[]) {
        A a1 = new A();
        A a2 = new A();
        //start1
        System.out.println("通过a1来设置x和y的值");
        a1.setx(1);
        a1.showx();
        a2.showx();
        a1.sety(2);
        a1.showy();
        a2.showy();
        //start2
        System.out.println("通过a2来设置x和y的值");
        a2.setx(3);
        a1.showx();
        a2.showx();
        a2.sety(4);
        a1.showy();
        a2.showy();
    }
}

示例3-15

class Point {
    int x, y;

    void setXY(int x1, int y1) {
        x = x1;
        y = y1;
    }

    void squarePoint(Point p) {
        p.x = p.x * p.x;
        p.y = p.y * p.y;
    }
}

public class JBT3505 {
    public static void main(String args[]) {
        Point p0 = new Point();
        p0.setXY(10, 20);
        System.out.println("x=" + p0.x + "...y=" + p0.y);
        p0.squarePoint(p0);
        System.out.println("x=" + p0.x + "...y=" + p0.y);
    }
}

示例3-16

public class JBT3506 {
    public static void main(String args[]) {
        int a[] = new int[6];
        for (int i = 0; i < a.length; i++)
            a[i] = i;
        for (int i = 0; i < a.length; i++)
            System.out.println("a[" + i + "]=" + a[i]);
        addN(a, 10);
        for (int i = 0; i < a.length; i++)
            System.out.println("a[" + i + "]=" + a[i]);
    }

    static void addN(int b[], int N) {
        for (int i = 0; i < b.length; i++)
            b[i] = b[i] + N;
    }
}

课后4-1

public class Main {
    public static void main(String args[]) {
        myBox obj = new myBox();
        int x = 10, y = 20;
        obj.setvalue(x, y);
        System.out.println("width=" + obj.width + " length=" + obj.length);
        System.out.println("周长=" + obj.circle());
        System.out.println("面积=" + obj.area());
    }
}

class myBox {
    int width, length;

    void setvalue(int width, int length) {
        this.width = width;
        this.length = length;
    }

    int circle() {
        return 2 * (width + length);
    }

    int area() {
        return width * length;
    }
}