爪哇咖啡屋 : [自創]測試Java的四捨五入、無條件捨去、無條件進位

/* ========================================================================== */
/*	TestRound.java
/*	(c) 2005 Author 冷日
/*	Description	
/*	因為冠宇說VBA裡面的round會做『偶數四捨五入』，12.5四捨五入=12 、 13.5四捨五入=14 、 10.5四捨五入=10 、 11.5四捨五入=12
/*	所以來測試Java的Round，雖然冷日覺得就是M$在耍白痴！(順便測無條件進位ceil和捨去floor)
/* ========================================================================== */

import java.io.*;
import java.lang.*;

class TestRound {
	public static void main(String[] args) {
		double x = 11.3 , y = 12.6 , z = 13.52145 ;
		System.out.println( "x is " + x + " after round is " + (int)Math.round(x) + "!" );
		System.out.println( "y is " + y + " after round is " + (int)Math.round(y) + "!" );
		System.out.println( "z is " + z + " after round is " + (int)Math.round(z) + "!");
		System.out.println( "x is " + x + " after floor is " + (int)Math.floor(x) + "!" );
		System.out.println( "x is " + x + " after ceil is " + (int)Math.ceil(x) + "!" );
		System.out.println( "z is " + z + " after floor is " + (int)Math.floor(z) + "!");
		System.out.println( "z is " + z + " after ceil is " + (int)Math.ceil(z) + "!");
	}
}

---------- Run ----------
x is 11.3 after round is 11!
y is 12.6 after round is 13!
z is 13.52145 after round is 14!
x is 11.3 after floor is 11!
x is 11.3 after ceil is 12!
z is 13.52145 after floor is 13!
z is 13.52145 after ceil is 14!
Normal Termination
輸出完成 (耗時 0 秒).

/* ========================================================================== */
/* ========================================================================== */
/*	TestRound2.java
/*	(c) 2009 Author 冷日
/*	Description	
/*	網站上有人問 double i=100.22 , j=32.33 , k=Math.round(i*j);
/*	那會做如何的計算？取第幾位呢?如果k要四捨五入到小數點第一位該做怎樣的處理呢?
/* ========================================================================== */

import java.io.*;
import java.lang.*;

class TestRound2 {
	public static void main(String[] args) {
		double i , j , k , l , m  , n; 
		i = 100.24;
		j = 32.33;
		k = ( i * j ) ;
		l = Math.round( k );
		m = Math.round( k * 100 );
		n = m / 100 ;
		System.out.println("k is : " + k);
		System.out.println("l is : " + l);
		System.out.println("m is : " + m);
		System.out.println("n is : " + n);
	}
}

---------- Run ----------
k is : 3240.7591999999995
l is : 3241.0
m is : 324076.0
n is : 3240.76

輸出完成 (耗費 0 秒)。 - 正常結束