Help with char and string

[mehnihma]

I am very new to Java and have problems understating char function


I have lab in which asks to do:

Method: calcPoints
Parameters/Return: One parameter with letter grade of type char. Returns the points for the grade
Purpose: Converts the grade to its equivalent point value.
You must use a switch statement in the method calcPoints to convert the grade to its equivalent number of points. If the letter grade is not a valid grade, return a value of -1.

And I do not get do I need to use string or char, or to you string and later chat to take a first letter?


I am confused so sorry if I wrote it confusing.

Thanks

[justinm231]

Well assuming the letter grade letter is being passed as a String to your class, then you will need to cast it to a char:

String grade = (char) gradeChar;

then you will put the gradeChar as your parameter in the switch statement as:

switch ('gradeChar')
case A: 100; break;
...
etc.

Does this help? I should let you know, I am a beginner as well.

[mehnihma]

I think it helps :D

I will try it

thanks

[mehnihma]

The problems is that I need to tell the program if someone enters “Abacus”, the letter grade would be the character ‘A’ in case switch and I don't know how to do it :)

[Junky]

String grade = (char) gradeChar;

Perhaps you should check things before offering incorrect advice. Not only can you NOT cast a String to a char you then assign it back to a String variable. What is the point of that. Plus the instructions say that the value will be passed as a char so why are you bothering with a String anyway?

switch ('gradeChar')
case A: 100; break;

Once again incorrect code and bad advice.

[mehnihma]

The what would be the best way to do it?

This is my problem :

          grade = input.next(); // read grade from user
			  
			  char cgrade = grade.charAt(0);
			// case switch
			  
			  switch (cgrade) { 
			  
			  
			  
			                                
                case "A":              
                case "a":
               System.out.println("Points: 4");
                    break;
                case "b":
                case "B":
                    System.out.println("Points: 3");
                    break;
                case "c":
                case "C":
                    System.out.println("Points: 2");
                    break;
                case "d":
                case "D":
                   System.out.println("Points: 1");
                    break;
               case "f":
                case "F":
                    System.out.println("Points: 0");
				       break;
					 default:
                System.out.println("Points: -1");
                break;
                    
            }// end switch

[mehnihma]

Is it possible just to take first letter from

grade = input.next();

and pass it to switch?

[Junky]

You cannot switch on Strings (at least not in versions 1.6 and lower). You have to switch on chars. By that I mean your case statements.

[Junky]

Is it possible just to take first letter from

grade = input.next();

and pass it to switch?

Yes, line 3 of the code above does that.

[mehnihma]

is this correct way do do it?

grade = input.next(); // read grade from user
			  
			  char c = grade.charAt(0);  // from string to Character 
			  
			  
			  
			  String grade1 = Character.toString(c); // converting to string

[mehnihma]

Yes, line 3 of the code above does that.

when I do that I get error in switch that it should be char?

[Junky]

:headdesk:

The code you posted in reply 6 is almost correct. The point I was trying to make is that in your case statements you have the letters as Strings (which you cannot do in switches) when they should be chars.

String grade1 = Character.toString(c); // converting to string
Delete this line as it is totally unnecessary.

[mehnihma]

This way it's working but whiteout it it is not working?

how can I write them as chars?

[mehnihma]

aha is it 'A' not the "A" for char?

I think this is new for java 1.7 and that is why it's working