Java将int转换为char不起作用

Question

I use Java 7 SE on Win7 Pro and have this problem: Converting int to char doesn't work properly.

What is wrong?

Thanks.

int oneInt = 1;
char oneChar = '1';

// prints false
System.out.println((char) oneInt == oneChar);

// prints this symbol 
oneChar = (char) 1;
System.out.println(oneChar);

// Works - it prints 1 
oneChar = (1 + "").charAt(0);
System.out.println(oneChar);

Answer 1

The char '1' is not the same as the integer value 1 . It's equals to the value of the ASCII code which represents '1' . You can find all the ASCII values' encodings here

If you want to convert a char into an integer like that, you need to subtract '0' (the character 0, not the integer) from it first. Since all the integers are contiguous in ASCII, this will shift everything down so that '0' becomes 0 , '1' becomes 1 , etc.

Answer 2

You might consider using some static method built into the standard Java libraries.

For example, Integer.parseInt(String s) would take the string s and attempt to translate it to an integer. So Integer.parseInt("5") would return 5 as an integer.

String.valueOf(int i) would turn the integer into its String equivalent. So String.valueOf(10) would return "10" as a string.

If you're actually using chars and not just strings, this might help out: https://docs.oracle.com/javase/7/docs/api/java/lang/Character.html

There's methods like getNumericValue and isDigit. Not sure if that's exactly what you're looking for, but it might be cleaner than using magic numbers like adding 48 to get the char you're looking for.