Java programming help Plz

[Slyvr]

Hey,
So I'm in this java class and our newest assignment is to test whether data input is valid and then do some kinda output. I'm having trouble figuring out a way to determine if a string starts with an Uppercase and is followed by lowercase (As for a first and last name). I think I need to break the string up into an array and then determine if the array[0] is uppercase, then...some other crap for lowercase, idk.

Anyways, anybody know java that can tell me what I need to use to break up a string like that and then test for upper or lower case?

[Lenny]

No need to put them into an array - you can use str.charAt(0) and str.charAt(1) for the first and second letters.

It's a wee bit hacky but you could try checking if the first letter is uppercase by comparing it to itself in uppercase:

return (str.charAt(0).equals(str.charAt(0).toUppercase()) );

The same can be done for the second letter.

I think it will work. I don't have a copy of the API to hand, so I can't give you a better answer right now.

[Lenny]

I've had a look at the API, and I can't see another way to do it. I made a small mistake above - you can't tack .equals on the end of a char. Instead, get the first char using charAt and add it to a string, then return the result of the comparison.

This is very simple, so I have no qualms in giving you the code, but when you get to more complex things I'll just give you a push in the right direction.


public class CheckCharCase {

public static void main(String[] args) {
System.out.println("" + getFirst("Hello")); //true
System.out.println("" + getFirst("hello")); //false
System.out.println("" + getSecond("Hello")); //true
System.out.println("" + getSecond("HEllo")); //false
}

private static boolean getFirst(String s) {
String str = "" + s.charAt(0);
//get the first char of the string, put into a string
return(str.equals(str.toUpperCase()));
//compare and return
}

private static boolean getSecond(String s) {
String str = "" + s.charAt(1);
return(str.equals(str.toLowerCase()));
}
}

[Demosthenes]

Another method if you want it:

Suppose you have String str. Then you could say:

Character.isUpperCase(str.charAt(0));

This returns a boolean value.

So you might have something like


if(Character.isUpperCase(str.charAt(0)))
{
// do something
}
else
{
// do something else
}
.

Here are a couple of links that might help:

http://java.sun.com/j2se/1.4.2/docs/api/java/lang/Character.html
http://java.sun.com/j2se/1.4.2/docs/api/java/lang/String.html

[Lenny]

I remembered that in the middle of my last lecture. :(

[Slyvr]

Thank you good sirs. I'm sure that'll work. I don't have time now, but tomorrow I'll finish the program and see if it compiles and runs correctly. Damn my procrastination.

[Slyvr]

Thank youu. The .charAt worked but I still have a problem. I need to know how many characters are in each string now so I can test each string's characters if they are lowercase. This is what I have so far for that portion...but I get a String Index Out Of Bounds Exception:
for (i=0; i<30; i++){
if (Character.isLetterOrDigit(LastName.charAt(i))){
LastChar_count++;
}
else{
break;
}
}
for (i=0; i<30; i++){
if (Character.isLetterOrDigit(FirstName.charAt(i))){
FirstChar_count++;
}
else{
break;
}
}

I just need to count the number of characters.

[Knight Sir Rick]

Thank youu. The .charAt worked but I still have a problem. I need to know how many characters are in each string now so I can test each string's characters if they are lowercase. This is what I have so far for that portion...but I get a String Index Out Of Bounds Exception:


You can use the String method length() to determine how many characters there are in a string object. For instance, you may want to use something like for(int i=0; i < LastName.length(); i++) to iterate through each character in the string LastName.

[Demosthenes]

If you want to see if all the characters in a string are lowercase, for String str, then you can do the following


if(str.compareTo(str.toLowerCase())!=0)
{
// do this if the string is not lower case
}
else
{
// do this if string is lower case
}


No loops necessary.

[Slyvr]

Thanks, I realized I could use the .length like ten minutes after posting this Lol. I finished the program and it works nicely. Thanks for your help