此Java println调用中的char转换有什么作用？

Question

I'm new to programming in java and I do not understand a println statement. I can run it but cannot understand what it does. Can anyone explain what this does?

System.out.println((char) ('a' + 4));

Answer 1

1. 'a' is a char literal;
2. char is an intergral numeric type in Java, just like int ;
3. + occurring between two numeric values means addition ;
4. (char) indicates a conversion into a char type;
5. a char , when printed, renders as the Unicode codepoint it represents.

Answer 2

That simply prints out the letter e . @wrongAnswer has referenced the ASCII character codes, which is a numbering system that assigns unique IDs to characters. Take a look at this one for example: http://www.asciitable.com/ .

If you take a look at the way the lower case letters are arranged in the table, you'll see that the letter a is at 97, b is at 98, c is at 99 and so on. What the above code is doing is that we are finding what the ASCII code of a is, then adding by 4, then casting back to char . Therefore, what this is actually doing is taking 97 then adding with 4 , producing 101 . If you consult the table, 101 is actually e , and so the output is e after casting 101 with char .

Answer 3

the ascii value of a is 97 so 97+4=101 101 which is ascii value of alphabets e .

System.out.println((char) ('a' + 4)); 

so the above sop will print e .

Answer 4

Lets break this down into discrete statements:

char a = 'a'; // the character a
int aPlusFour = a + 4; //characters are really an integer value for the ASCII code, so we can add four 
char aPlusFourChar = ((char) aPlusfour); //cast our integer back to a char
System.out.println(aPlusFourChar); //this should print the character e

Answer 5

1. 'a' == 97
2. 97+4 == 101
3. (char)101 == 'e'
4. System.out.println('e'+""); // prints 'e'

Answer 6

首先将ascii值添加到值4，然后打印与值101对应的字符。它是'e'。您可以参考ascii表