Guava LongMath类
Guava LongMath类
LongMath提供long基础类型的实用方法。

类声明

以下是com.google.common.math.LongMath类的声明：

@GwtCompatible(emulated=true)
public final class LongMath
extends Object
方法

方法继承

这个类继承了以下类方法：

java.lang.Object

LongMath 示例

使用所选择的任何编辑器创建下面的java程序 C:/> Guava GuavaTester.java

import java.math.RoundingMode;
import com.google.common.math.LongMath;

public class GuavaTester {

public static void main(String args[]){
GuavaTester tester = new GuavaTester();
tester.testLongMath();
}

private void testLongMath(){
try{
System.out.println(LongMath.checkedAdd(Long.MAX_VALUE, Long.MAX_VALUE));
}catch(ArithmeticException e){
System.out.println("Error: " + e.getMessage());
}

  System.out.println(LongMath.divide(100, 5, RoundingMode.UNNECESSARY));
  try{
     //exception will be thrown as 100 is not completely divisible by 3 thus rounding
     // is required, and RoundingMode is set as UNNESSARY
     System.out.println(LongMath.divide(100, 3, RoundingMode.UNNECESSARY));
  }catch(ArithmeticException e){
     System.out.println("Error: " + e.getMessage());
  }

  System.out.println("Log2(2): "+LongMath.log2(2, RoundingMode.HALF_EVEN));

  System.out.println("Log10(10): "+LongMath.log10(10, RoundingMode.HALF_EVEN));

  System.out.println("sqrt(100): "+LongMath.sqrt(LongMath.pow(10,2), RoundingMode.HALF_EVEN));

  System.out.println("gcd(100,50): "+LongMath.gcd(100,50));

  System.out.println("modulus(100,50): "+LongMath.mod(100,50));

  System.out.println("factorial(5): "+LongMath.factorial(5));

}
}
验证结果

使用javac编译器编译如下类

C:Guava>javac GuavaTester.java
现在运行GuavaTester看到的结果

C:Guava>java GuavaTester
看到结果

Error: overflow
20
Error: mode was UNNECESSARY, but rounding was necessary
Log2(2): 1
Log10(10): 1
sqrt(100): 10
gcd(100,50): 50
modulus(100,50): 0
factorial(5): 120