Exchanging values of variables and printing problems

Question

Hi, everyone
I have two questions
First one:
Write the definition of a method  printGrade , which has a  char parameter and returns nothing. The method prints on a line by itself the message string  Grade: followed by the  char parameter (printed as a character) to standard output. Don't forget to put a new line character at the end of your line.
and my code is:
public static void String printGrade(char A){
System.out.println("Grade:" +A+ "\n");
}My question is:
1.why the compiler asks me to delete the public and String. The method prints out a String messge, shouldn't I use String as the identifier of the method?
2. the problem ask me to print the char parameter as a character, in this case, should I use the + sign? if I use it, will the compiler return the value for String A?
Second one:
temp = i;
i=j;
j= temp;We use this method to exchange the values of i and j. My question is why the value of temp can stay unchanged when I write i=j? if I want the value stored in temp from i to j, but not by writing temp=j; what should I do?
Thank you very much for your help.

Answer 1

Terry001 wrote:
1.why the compiler asks me to delete the public and String. The method prints out a String messge, shouldn't I use String as the identifier of the method?The compiler doesn't care what your method prints. Printing is just another method you call. It cares what, if anything, your method returns, and you've already stated that with void.
2. the problem ask me to print the char parameter as a character, in this case, should I use the + sign? if I use it, will the compiler return the value for String A?The + is fine. "Printing 'as a character'" doesn't make any sense.
Also, you don't need the \n, since a) println already adds a newline, and b) \n is not the line terminator on all platforms.
Second one:
temp = i;
i=j;
j= temp;We use this method to exchange the values of i and j. My question is why the value of temp can stay unchanged when I write i=j?Because i and temp are two totally separate variables. Doing "temp = i" does NOT mean that are now "aliases" for each other. It just means that whatever value was in i at that point is copied to temp. Further changes to i do not affectd temp, and vice versa.
if I want the value stored in temp from i to j, but not by writing temp=j; what should I do?Find a different language. The only way to get j's value into temp in Java is with temp = j. (Or, I suppose temp = somethingElse, where you previously put j's value into somethingElse, but that amounts to the same thing.)