双十六进制字符串和后面 [英] Double to Hex String and Back

问题描述

在Java中将double转换为十六进制字符串非常简单。但是我该怎么做呢？我的代码在下面，我已经注意到一个 NumberFormatException 被抛出（大约2/3秒）。

  public class HexToDoubleTest {
 public static void main（String args []）{
 
 //这是起始double值
 double doubleInput = -9.156013e-002; 
 
 //将起始值转换为长
 long中的等效值double doubleLong = Double.doubleToRawLongBits（doubleInput）; 
 
 //将long转换为字符串
 String doubleAsString = Long.toHexString（doubleAsLong）; 
 
 //打印字符串
 System.out.println（doubleAsString）; 
 
 //尝试将字符串解析为long 
 // !!!这将失败与NumberFormatException !!! 
 long doubleAsLongReverse = Long.parseLong（doubleAsString，16）; 
 
 //将long返回到原来的double 
 double doubleOutput = Double.longBitsToDouble（doubleAsLongReverse）; 
 
 //确认值匹配
 assert（doubleInput == doubleOutput）; 
 
} 
} 
  

使用 Double.valueOf 以相同的方式失败。

编辑：我已经在网上完成了几次搜索，发现了一些非常不方便的解决方案。例如：使用 BigInteger 似乎过于杀伤。必须有一个更好的方法！

解决方案

您可以将String分解成两半并解析每个，但我认为是最简单的。

  long doubleAsLongReverse = new BigInteger（doubleAsString，16）.longValue（）; 
  

It's fairly simple to convert a double to a hexadecimal string in Java. But how do I do the reverse? My code is below and I've noted where a NumberFormatException is thrown (about 2/3rds down).

public class HexToDoubleTest {
    public static void main( String args[] ) {

        // This is the starting double value
        double doubleInput = -9.156013e-002;

        // Convert the starting value to the equivalent value in a long
        long doubleAsLong = Double.doubleToRawLongBits( doubleInput );

        // Convert the long to a String
        String doubleAsString = Long.toHexString( doubleAsLong );

        // Print the String
        System.out.println( doubleAsString );

        // Attempt to parse the string back as a long
        // !!! This fails with a NumberFormatException !!!
        long doubleAsLongReverse = Long.parseLong( doubleAsString, 16 );

        // Convert the long back into the original double
        double doubleOutput = Double.longBitsToDouble( doubleAsLongReverse );

        // Confirm that the values match
        assert( doubleInput == doubleOutput );

    }
}

Using Double.valueOf fails in the same manner.

Edit: I've done a few searches on the web already and found some very inelegant solutions. For example: Using a BigInteger seems like overkill. There's got to be a better way!

解决方案

You can break the String into two halves and parse each one, but I think this is the simplest.

long doubleAsLongReverse = new BigInteger(doubleAsString, 16).longValue();

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