类Math

Math类

/*
 * Math:用于数学运算的类
 * 成员变量：
 * public static final double PI
 * public static final double E
 * 成员方法：
 * public static int abs(int a)绝对值
 * public static double ceil(double a)向上取整
 * public static double floor(double a)向下取整
 * public static int max(int a,int b)最大值
 * public static double pow(double a,double b)a的b次幂
 * public static double random()随机数[0.0,1.0]
 * public static int round(float a)四舍五入
 * public static double sqrt(double a)正平方根
 * */

public class IntegerDemo {

	public static void main(String[] args) {
		// TODO Auto-generated method stub

		// public static final double PI
		System.out.println("PI:" + Math.PI);

		// public static final double E
		System.out.println("E:" + Math.E);

		// public static int abs(int a)绝对值
		System.out.println("abc:" + Math.abs(100));
		System.out.println("abc:" + Math.abs(-100));

		// public static double ceil(double a)向上取整
		System.out.println("ceil:" + Math.ceil(12.34));
		System.out.println("ceil:" + Math.ceil(12.56));

		// public static double floor(double a)向下取整
		System.out.println("floor:" + Math.floor(12.34));
		System.out.println("floor:" + Math.floor(12.56));

		// public static int max(int a,int b)最大值
		System.out.println("max:" + Math.max(12, 23));
		System.out.println("max:" + Math.max((Math.max(12, 23)), 18));

		// public static double pow(double a,double b)a的b次幂
		System.out.println("pow:" + Math.pow(2, 3));

		// public static double random()随机数[0.0,1.0]
		System.out.println("random:" + Math.random());
		System.out.println("random:" + (int) (Math.random() * 100) + 1);

		// public static int round(float a)四舍五入
		System.out.println("round:" + Math.round(12.34f));
		System.out.println("round:" + Math.round(12.56f));

		// public static double sqrt(double a)正平方根
		System.out.println("sqrt:" + Math.sqrt(4));
	}
}

/*
* 需求：请设计一个方法，可以实现获取任意范围内的随机数
*
* A:键盘录入两个数据
* int start
* int end
*
* B:获取在start和end之间的随机数
*
* C:输出这个随机数
* */

import java.util.Scanner;

/*
 * 需求：请设计一个方法，可以实现获取任意范围内的随机数
 * 
 * A:键盘录入两个数据
 * int start
 * int end
 * 
 * B:获取在start和end之间的随机数
 * 
 * C:输出这个随机数
 * */

public class IntegerDemo {

	public static void main(String[] args) {
		// TODO Auto-generated method stub

		Scanner sc = new Scanner(System.in);

		System.out.println("请输入开始数据：");
		int start = sc.nextInt();

		System.out.println("请输入结束数据：");
		int end = sc.nextInt();

		for (int i = 0; i < 100; i++) {
			int result = getRandom(start, end);

			System.out.println(result);
		}
	}

	public static int getRandom(int start, int end) {
		int result = (int) (Math.random() * (end - start + 1)) + start;

		return result;
	}
}