java中常用到的math方法（Math.PI、Math.random()、Math.abs(double)、Math.floor(double)、Math.ceil(double)、Math.round(double)）

public class MathDemo {

public static void main(String args[]){

/**

* abs求绝对值

*/

System.out.println(Math.abs(-10.4)); //10.4

System.out.println(Math.abs(10.1)); //10.1

/**

* ceil天花板的意思，就是返回大的值，注意一些特殊值

*/

System.out.println(Math.ceil(-10.1)); //-10.0

System.out.println(Math.ceil(10.7)); //11.0

System.out.println(Math.ceil(-0.7)); //-0.0

System.out.println(Math.ceil(0.0)); //0.0

System.out.println(Math.ceil(-0.0)); //-0.0

/**

* floor地板的意思，就是返回小的值

*/

System.out.println(Math.floor(-10.1)); //-11.0

System.out.println(Math.floor(10.7)); //10.0

System.out.println(Math.floor(-0.7)); //-1.0

System.out.println(Math.floor(0.0)); //0.0

System.out.println(Math.floor(-0.0)); //-0.0

/**

* max 两个中返回大的值,min和它相反，就不举例了

*/

System.out.println(Math.max(-10.1, -10)); //-10.0

System.out.println(Math.max(10.7, 10)); //10.7

System.out.println(Math.max(0.0, -0.0)); //0.0

/**

* random 取得一个大于或者等于0.0小于不等于1.0的随机数

*/

System.out.println(Math.random()); //0.08417657924317234

System.out.println(Math.random()); //0.43527904004403717

/**

* rint 四舍五入，返回double值

* 注意.5的时候会取偶数

*/

System.out.println(Math.rint(10.1)); //10.0

System.out.println(Math.rint(10.7)); //11.0

System.out.println(Math.rint(11.5)); //12.0

System.out.println(Math.rint(10.5)); //10.0

System.out.println(Math.rint(10.51)); //11.0

System.out.println(Math.rint(-10.5)); //-10.0

System.out.println(Math.rint(-11.5)); //-12.0

System.out.println(Math.rint(-10.51)); //-11.0

System.out.println(Math.rint(-10.6)); //-11.0

System.out.println(Math.rint(-10.2)); //-10.0

/**

* round 四舍五入，float时返回int值，double时返回long值

*/

System.out.println(Math.round(10.1)); //10

System.out.println(Math.round(10.7)); //11

System.out.println(Math.round(10.5)); //11

System.out.println(Math.round(10.51)); //11

System.out.println(Math.round(-10.5)); //-10

System.out.println(Math.round(-10.51)); //-11

System.out.println(Math.round(-10.6)); //-11

System.out.println(Math.round(-10.2)); //-10

}

}

public class MathDemo {

public static void main(String args[]){

/**

* abs求绝对值

*/

System.out.println(Math.abs(-10.4)); //10.4

System.out.println(Math.abs(10.1)); //10.1

/**

* ceil天花板的意思，就是返回大的值，注意一些特殊值

*/

System.out.println(Math.ceil(-10.1)); //-10.0

System.out.println(Math.ceil(10.7)); //11.0

System.out.println(Math.ceil(-0.7)); //-0.0

System.out.println(Math.ceil(0.0)); //0.0

System.out.println(Math.ceil(-0.0)); //-0.0

/**

* floor地板的意思，就是返回小的值

*/

System.out.println(Math.floor(-10.1)); //-11.0

System.out.println(Math.floor(10.7)); //10.0

System.out.println(Math.floor(-0.7)); //-1.0

System.out.println(Math.floor(0.0)); //0.0

System.out.println(Math.floor(-0.0)); //-0.0

/**

* max 两个中返回大的值,min和它相反，就不举例了

*/

System.out.println(Math.max(-10.1, -10)); //-10.0

System.out.println(Math.max(10.7, 10)); //10.7

System.out.println(Math.max(0.0, -0.0)); //0.0

/**

* random 取得一个大于或者等于0.0小于不等于1.0的随机数

*/

System.out.println(Math.random()); //0.08417657924317234

System.out.println(Math.random()); //0.43527904004403717

/**

* rint 四舍五入，返回double值

* 注意.5的时候会取偶数

*/

System.out.println(Math.rint(10.1)); //10.0

System.out.println(Math.rint(10.7)); //11.0

System.out.println(Math.rint(11.5)); //12.0

System.out.println(Math.rint(10.5)); //10.0

System.out.println(Math.rint(10.51)); //11.0

System.out.println(Math.rint(-10.5)); //-10.0

System.out.println(Math.rint(-11.5)); //-12.0

System.out.println(Math.rint(-10.51)); //-11.0

System.out.println(Math.rint(-10.6)); //-11.0

System.out.println(Math.rint(-10.2)); //-10.0

/**

* round 四舍五入，float时返回int值，double时返回long值

*/

System.out.println(Math.round(10.1)); //10

System.out.println(Math.round(10.7)); //11

System.out.println(Math.round(10.5)); //11

System.out.println(Math.round(10.51)); //11

System.out.println(Math.round(-10.5)); //-10

System.out.println(Math.round(-10.51)); //-11

System.out.println(Math.round(-10.6)); //-11

System.out.println(Math.round(-10.2)); //-10

}

}