明解JAVA第二章答案

test2-1

public class test2_1 {
    public static void main(String[] args)
    {
        double x;
        double y;

        x=63.2;
        y=18.6;

        System.out.println("x的值是"+x+"。");
        System.out.println("y的值是"+y+"。");
        System.out.println("合计值是"+(x+y)+"。");
        System.out.println("平均值是"+(x+y)/2+"。");
    }
}

           

test2-2

public class test2_2 {
    public static void main(String[] args)
    {
        int x,y,z;

        x=1;
        y=2;
        z=3;

        System.out.println("x,y,z的平均数是"+(x+y+z)/3+"。");
    }
}

           

test2-3

import java.util.Scanner;
public class test2_3 {
    public static   void main(String[] args)
    {
        Scanner stdIn = new Scanner(System.in);
        System.out.println("请输入一个整数：");
        int a = stdIn.nextInt();
        System.out.println(a);
    }
}


           

test2-4

import java.util.Scanner;
public class test2_4 {
    public static void main(String[] args) {
        Scanner stdIn = new Scanner(System.in);
        System.out.println("Please enter a integer:");

        int a=stdIn.nextInt();

        System.out.println(a+10);
        System.out.println(a-10);
    }
}
           

test2-5

import java.util.Scanner;
public class test2_5 {
    public static void main(String[] args) {
        Scanner stdIn = new Scanner(System.in);

        System.out.println("请输入x的值：");
        double x=stdIn.nextDouble();

        System.out.println("请输入y的值：");
        double y=stdIn.nextDouble();
        System.out.println("x:"+x);
        System.out.println("y:"+y);
        System.out.println("x,y的和"+(x+y));
        System.out.println("x,y的平均值"+(x+y)/2);
    }
}

           

test2-6

import java.util.Scanner;
public class test2_6 {
    public static void main(String[] args) {
        Scanner stdIn = new Scanner(System.in);

        System.out.println("请输入底的长度：");
        double d=stdIn.nextDouble();

        System.out.println("请输入高的长度：");
        double h=stdIn.nextDouble();

        System.out.println("底:"+d);
        System.out.println("高"+h);
        System.out.println("面积："+d*h/2);
    }
}

           

test2-7

import java.lang.Math;
public class test2_7 {
    public static void main(String[] args) {

        int a=(int)(Math.random()*10);
        int b=-(int)(Math.random()*10);
        int c=(int)(10+Math.random()*90);

        System.out.println(a);
        System.out.println(b);
        System.out.println(c);


    }
}

           

test2-8

import java.lang.Math;
import java.util.Random;
import java.util.Scanner;
public class test2_8 {
    public static void main(String[] args) {
        Random random=new Random();
        Scanner stdIn=new Scanner(System.in);

        int a=random.nextInt();
        int b=a/Math.abs(a);
        int c=random.nextInt(6);
        int d=stdIn.nextInt();
        System.out.println(d+c*a);

    }

}

           

test2-9

import java.util.Random;
public class test2_9 {
    public static void main(String[] args) {
        Random  random=new Random();

        double a=random.nextDouble();
        System.out.println(a);

        double b=random.nextDouble()*10;
        System.out.println(b);

        double c=-1+random.nextDouble()*2;
        System.out.println(c);
    }
    }


           

test2-10

import java.util.Scanner;
public class test2_10 {
    public static void main(String[] args)
    {
        Scanner stdIn=new Scanner(System.in);

        System.out.println("Please enter your last name:");
        String a=stdIn.next();
        System.out.println("Please enter your first name:");
        String b=stdIn.next();

        System.out.println("你好"+a+b+"先生");
    }
}