Guava教程

Guava LongMath類

 

LongMath提供long基礎類型的實用方法。

 

類聲明

 

以下是com.google.common.math.LongMath類的聲明:

 

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

 

方法

 

 

方法繼承

 

這個類繼承了以下類方法:

java.lang.Object


LongMath 示例

 

使用所選擇的任何編輯器創建下面的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));
   }
}

 

驗證結果

 

使用javac編譯器編譯如下類

 

C:\Guava>javac GuavaTester.java


現在運行GuavaTester看到的結果

 

C:\Guava>java GuavaTester

 

看到結果

 

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

 
 

 

 

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