Java-将二进制解析为long [英] Java - parse binary to long

问题描述

我有一个数字的二进制表示形式，想将其转换为long(我有Java 8)

I have a binary represenation of a number and want to convert it to long (I have Java 8)

public class TestLongs {
public static void main(String[] args){
    String a = Long.toBinaryString(Long.parseLong("-1")); // 1111111111111111111111111111111111111111111111111111111111111111
    System.out.println(a);
    System.out.println(Long.parseLong(a, 2));// ??? but Long.parseUnsignedLong(a, 2) works
}

}

此代码导致Exception in thread "main" java.lang.NumberFormatException: For input string: "1111111111111111111111111111111111111111111111111111111111111111" at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65) 1111111111111111111111111111111111111111111111111111111111111111 at java.lang.Long.parseLong(Long.java:592) 这是怎么了为什么Long.parseLong(a，2)不起作用?

This code results in Exception in thread "main" java.lang.NumberFormatException: For input string: "1111111111111111111111111111111111111111111111111111111111111111" at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65) 1111111111111111111111111111111111111111111111111111111111111111 at java.lang.Long.parseLong(Long.java:592) What is wrong here? Why Long.parseLong(a, 2) doesn't work?

推荐答案

Long.parseLong()不会将第一个'1'字符视为符号位，因此该数字将解析为2 ^ 64-1，这也是如此对于long而言较大. Long.parseLong()期望代表负数的输入String以'-'开头.

Long.parseLong() doesn't treat the first '1' character as a sign bit, so the number is parsed as 2^64-1, which is too large for long. Long.parseLong() expects input Strings that represent negative numbers to start with '-'.

为了使Long.parseLong(str,2)返回-1，您应该向其传递一个以'-'开头并以1的二进制表示形式-即Long.parseLong("-1",2)的String.

In order for Long.parseLong(str,2) To return -1, you should pass to it a String that start with '-' and ends with the binary representation of 1 - i.e. Long.parseLong("-1",2).

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