Math:用于数学运算的类

package ss1;
/*
 * 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 (min自学)
 *  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(参数为double的自学)
 *  public static double sqrt(double a):正平方根
 */

public class Menu {
 public static void main(String[] args) {
    // public static final double PI
    System.out.println("PI:" + Math.PI);
    // public static final double E
    System.out.println("E:" + Math.E);
    System.out.println("--------------");

    // public static int abs(int a)：绝对值
    System.out.println("abs:" + Math.abs(10));
    System.out.println("abs:" + Math.abs(-10));
    System.out.println("--------------");

    // 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));
    System.out.println("--------------");

    // 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));
    System.out.println("--------------");

    // public static int max(int a,int b):最大值
    System.out.println("max:" + Math.max(12, 23));
    // 需求：我要获取三个数据中的最大值
    // 方法的嵌套调用
    System.out.println("max:" + Math.max(Math.max(12, 23), 18));
    // 需求：我要获取四个数据中的最大值
    System.out.println("max:"
      + Math.max(Math.max(12, 78), Math.max(34, 56)));
    System.out.println("--------------");

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

    // public static double random():随机数 [0.0,1.0)
    System.out.println("random:" + Math.random());
    // 获取一个1-100之间的随机数
    System.out.println("random:" + ((int) (Math.random() * 100) + 1));
    System.out.println("--------------");

    // public static int round(float a) 四舍五入(参数为double的自学)
    System.out.println("round:" + Math.round(12.34f));
    System.out.println("round:" + Math.round(12.56f));
    System.out.println("--------------");
    
    //public static double sqrt(double a):正平方根
    System.out.println("sqrt:"+Math.sqrt(4));
 }
}

结果:

PI:3.141592653589793
E:2.718281828459045
--------------
abs:10
abs:10
--------------
ceil:13.0
ceil:13.0
--------------
floor:12.0
floor:12.0
--------------
max:23
max:23
max:78
--------------
pow:8.0
--------------
random:0.7956555742848289
random:40
--------------
round:12
round:13
--------------
sqrt:2.0