在二进制、十进制和八进制之间转换的内置 Java 类/方法？
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built-in Java classes/methods to convert between binary, decimal, and octal?
提问by dj.
i know of several general formulas for converting between binary, decimal, and octal, but i was wondering if java has any built-in methods or classes that convert between the three. for instance, in the Integer class, there are static methods such as toBinaryString, toOctalString, etc which allow for decimal conversion, but i haven't found any to convert the other way. anyone know of anything?
我知道几个用于在二进制、十进制和八进制之间转换的通用公式，但我想知道 java 是否有任何内置方法或类可以在这三者之间进行转换。例如，在 Integer 类中，有一些静态方法，例如 toBinaryString、toOctalString 等，它们允许进行十进制转换，但我还没有找到任何可以以其他方式转换的方法。有人知道什么吗？
in particular, i am looking for methods to convert from octal and binary to decimal and between octal and binary
特别是，我正在寻找从八进制和二进制转换为十进制以及在八进制和二进制之间转换的方法
thanks! x
谢谢！X
回答by toolkit
How about: parseInt(String s, int radix)
怎么样：parseInt(String s, int radix)
parseInt("-FF", 16) returns -255
parseInt("1100110", 2) returns 102
回答by Brian Schroth
Integer.parseInt takes an optional second parameter for the base to parse it in. So to get binary,
Integer.parseInt 需要一个可选的第二个参数作为基础来解析它。所以要得到二进制，
Integer.parseInt(value, 2);
Octal,
八进制，
Integer.parseInt(value,8);
回答by Kaleb Brasee
You're looking for Integer.parseInt(String s, int radix)and Integer.toBinaryString(int i), Integer.toOctalString(int i) and Integer.toHexString(int i). All of those are static method of the Integer class.
您正在寻找Integer.parseInt(String s, int radix)和 Integer.toBinaryString(int i)、Integer.toOctalString(int i) 和 Integer.toHexString(int i)。所有这些都是 Integer 类的静态方法。
So to turn F hex into 1111 binary:
因此，要将 F 十六进制转换为 1111 二进制：
int fifteen = Integer.parseInt("F", 16);
String fifteenInBinary = Integer.toBinaryString(fifteen);
fifteenInBinary would equal "1111";
十五InBinary 将等于“1111”；
回答by Aishwarya
Well you can use the method
那么你可以使用该方法
Integer.toBinaryString(val);
The code may look like:
代码可能如下所示：
public class NewClass4
{
public static void main(String[] args)
{
int value;
String binary;
Scanner sc=new Scanner(System.in);
value=sc.nextInt();
binary=Integer.toBinaryString(value);
System.out.println(binary);
}
}
回答by Fady Nabil Yacoub
You could use the Long.toBinaryString() or Long.toOctalString() to convert a decimal to binary or octal.
您可以使用 Long.toBinaryString() 或 Long.toOctalString() 将十进制转换为二进制或八进制。
here are 2 methods that convert from binary to decimal and from octal to decimal, you could also convert from octal to decimal then to binary using these methods.
这里有两种从二进制转换为十进制和从八进制转换为十进制的方法，您也可以使用这些方法从八进制转换为十进制然后再转换为二进制。
public long binaryToDecimal(String binary) {
long decimal = 0;
int power = 0;
for (int i = binary.length() - 1; i >= 0; i--) {
String digit = "" + binary.charAt(i);
decimal += Integer.parseInt(digit) * Math.pow(2, power++);
}
return decimal;
}
public long octalToDecimal(String octal) {
long decimal = 0;
int power = 0;
for (int i = octal.length() - 1; i >= 0; i--) {
String digit = "" + octal.charAt(i);
decimal += Integer.parseInt(digit) * Math.pow(8, power++);
}
return decimal;
}
