学校Java Week3

Week3

W3L1

public static void main(string[] args) {
    System.out.println("hello world");
	// ";"很重要
    System.out.println(10+5);
}

Variables

Stored in RAM

public static void main(string[] args) {
    int myLastOne;
    int myTotal = 9;
    int myLastOne = 1000 - myTotal;
    
    System.out.println(myLastOne);
    //PPT中的less:减去
}

Primitive Types Challenge

public static void main(string[] args) {
    int i = 50;
    long j = 50000 + 10*(10+20+50);
    System.out.println(j);
}

Float and double

public static void main(string[] args) {
    double pound = 8/0.45359237;
    System.out.println(pound);
}

Char and boolean

public static void main(string[] args) {
    
}

String

W3L2 ex1

import java.util.Scanner;

public class W3L2_ex1 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int y;
        int m;
        int d;

        y = scanner.nextInt();
        m = scanner.nextInt();
        d = scanner.nextInt();

//        double a = (double)y - (14-m)/12;
//        double b = a + a/4 - a/100 + a/400;
//        double c = (double)m + 12 * ((14-m) / 12) -2;

        int a = (int)(y - (14-m)/12);
        int b = (int)(a + a/4 - a/100 + a/400);
        int c = (int)(m + 12 * ((14-m) / 12) -2);

        int day = (int)(( d + b + (31*c)/12) % 7);

        System.out.println("It's day " + day + " !");
    }
}

W3L2 ex2

import java.util.Scanner;

public class W3L2_ex2 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        double x = scanner.nextDouble();
        double y = scanner.nextDouble();

        double r = Math.sqrt(x*x + y*y);
        double th = Math.atan2(y, x);

        System.out.println("r = " + r);
        System.out.println("theta = " + th);
    }
}

W3 CW1 3.1

import java.util.Scanner;

public class W3_CW1_31 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        double cyan = scanner.nextDouble();
        double magenta = scanner.nextDouble();
        double yellow = scanner.nextDouble();
        double black = scanner.nextDouble();

        double white = 1 - black;
        long red = Math.round(255 * white * (1-cyan));
        long green = Math.round(255 * white * (1-magenta));
        long blue = Math.round(255 * white * (1-yellow));

        System.out.println("red = " + red);
        System.out.println("green = " + green);
        System.out.println("blue = " + blue);

    }
}

W3 CW1 3.2

import java.util.Scanner;

public class W3_CW1_32 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        double x1 = Math.toRadians(scanner.nextDouble());
        double y1 = Math.toRadians(scanner.nextDouble());
        double x2 = Math.toRadians(scanner.nextDouble());
        double y2 = Math.toRadians(scanner.nextDouble());

        double dx = Math.sin((x2-x1)/2);
        double dy = Math.sin((y2-y1)/2);

        double dist = 2 * 6371.0 * Math.asin(Math.sqrt(dx*dx + Math.cos(x1) * Math.cos(x2) * dy*dy));

        System.out.println(dist + " kilometres");

    }
}