Develop Reference

Count how many list entries have a string property that ends with a particular char

I have an array list with some names inside it (first and last names). What I have to do is go through each "first name" and see how many times a character (which the user specifies) shows up at the end of every first name in the array list, and then print out the number of times that character showed up.
public int countFirstName(char c) {
int i = 0;
for (Name n : list) {
if (n.getFirstName().length() - 1 == c) {
i++;
}
}
return i;
}
That is the code I have. The problem is that the counter (i) doesn't add 1 even if there is a character that matches the end of the first name.

You're comparing the index of last character in the string to the required character, instead of the last character itself, which you can access with charAt:
String firstName = n.getFirstName()
if (firstName.charAt(firstName.length() - 1) == c) {
i++;
}

When you're setting out learning to code, there is a great value in using pencil and paper, or describing your algorithm ahead of time, in the language you think in. Most people that learn a foreign language start out by assembling a sentence in their native language, translating it to foreign, then speaking the foreign. Few, if any, learners of a foreign language are able to think in it natively
Coding is no different; all your life you've been speaking English and thinking in it. Now you're aiming to learn a different pattern of thinking, syntax, key words. This task will go a lot easier if you:
work out in high level natural language what you want to do first
write down the steps in clear and simple language, like a recipe
don't try to do too much at once
Had I been a tutor marking your program, id have been looking for something like this:
//method to count the number of list entries ending with a particular character
public int countFirstNamesEndingWith(char lookFor) {
//declare a variable to hold the count
int cnt = 0;
//iterate the list
for (Name n : list) {
//get the first name
String fn = n.getFirstName();
//get the last char of it
char lc = fn.charAt(fn.length() - 1);
//compare
if (lc == lookFor) {
cnt++;
}
}
return cnt;
}
Taking the bullet points in turn:
The comments serve as a high level description of what must be done. We write them aLL first, before even writing a single line of code. My course penalised uncommented code, and writing them first was a handy way of getting the requirement out of the way (they're a chore, right? Not always, but..) but also it is really easy to write a logic algorithm in high level language, then translate the steps into the language learning. I definitely think if you'd taken this approach you wouldn't have made the error you did, as it would have been clear that the code you wrote didn't implement the algorithm you'd have described earlier
Don't try to do too much in one line. Yes, I'm sure plenty of coders think it looks cool, or trick, or shows off what impressive coding smarts they have to pack a good 10 line algorithm into a single line of code that uses some obscure language features but one day it's highly likely that someone else is going to have to come along to maintain that code, improve it or change part of what it does - at that moment it's no longer cool, and it was never really a smart thing to do
Aominee, in their comment, actually gives us something like an example of this:
return (int)list.stream().filter(e -> e.charAt.length()-1)==c).count();
It's a one line implementation of a solution to your problem. Cool huh? Well, it has a bug* (for a start) but it's not the main thrust of my argument. At a more basic level: have you got any idea what it's doing? can you look at it and in 2 seconds tell me how it works?
It's quite an advanced language feature, it's trick for sure, but it might be a very poor solution because it's hard to understand, hard to maintain as a result, and does a lot while looking like a little- it only really makes sense if you're well versed in the language. This one line bundles up a facility that loops over your list, a feature that effectively has a tiny sub method that is called for every item in the list, and whose job is to calculate if the name ends with the sought char
It p's a brilliant feature, a cute example and it surely has its place in production java, but it's place is probably not here, in your learning exercise
Similarly, I'd go as far to say that this line of yours:
if (n.getFirstName().length() - 1 == c) {
Is approaching "doing too much" - I say this because it's where your logic broke down; you didn't write enough code to effectively implement the algorithm. You'd actually have to write even more code to implement this way:
if (n.getFirstName().charAt(n.getFirstName().length() - 1) == c) {
This is a right eyeful to load into your brain and understand. The accepted answer broke it down a bit by first getting the name into a temporary variable. That's a sensible optimisation. I broke it out another step by getting the last char into a temp variable. In a production system I probably wouldn't go that far, but this is your learning phase - try to minimise the number of operations each of your lines does. It will aid your understanding of your own code a great deal
If you do ever get a penchant for writing as much code as possible in as few chars, look at some code golf games here on the stack exchange network; the game is to abuse as many language features as possible to make really short, trick code.. pretty much every winner stands as a testament to condense that should never, ever be put into a production system maintained by normal coders who value their sanity
*the bug is it doesn't get the first name out of the Name object

How to get the class of a rule in Juzzy (fuzzy logic library)?

I've tried Juzzy in Java. After defining the membership functions, antecedents, consequences and my rule base, I tried to print the output of a sample input which I entered. I saw that the only output can be the defuzzication number (type of double). But I need the class of the rule which fires with a sample input, not the defuzzication number. Anyone knows about the appropriate function for my problem?

I think
rulebase.evaluate(0).get(tip)

The Swedish Chef Translator

So the context is, I have a CS project where input is taken in either word or sentence form, and then it is translated to what The Swedish Chef from The Muppets would say. I decided to take the input as one line of string, and send that line into a parser, which in turn would build an array out of translations of the input's letters. The conditions for what gets changed are defined within. the current error I am getting: (while using "INPUT" as input)
Exception in thread "main" java.lang.IndexOutOfBoundsException: Index: 3, Size: 1
at java.util.ArrayList.rangeCheckForAdd(Unknown Source)
at java.util.ArrayList.add(Unknown Source)
at SwedishTranslator.parseString(SwedishTranslator.java:62)
at SwedishTranslator.main(SwedishTranslator.java:12)
Currently it is supposed to just print the array, I wanted to worry about formatting after the fact.
The code:
Sorry for the walls of text but I can't find where the issue is exactly and I figured I would give it a shot here. Thanks in advance.

ind<=in.length() goes one step too far.
Use ind < in.length() or ind <= in.length() - 1

The error arrises on line 62 which I assume is in your big if else section.
Within there you have several ind++ calls. This increments the pointer you use in the loop. So if your code must go through several of these statements it will go beyond the array index.
Additionally you have an issue in the for loop as joval mentioned
Edit
The ++ unary operator increments the variable (-- decrements). Placing the ++ after the variable name (x++) will increment before evaluation, where ++x will increment after evaluation.
This is a common test question for CS students so I suggest you do some more research and practice regarding the operator.

You're making a couple of really understandable beginner mistakes here. Instead of explicitly fixing your code, I'll tell you about a couple of things that, if considered while reviewing and editing your code, will also fix your problem.
The documentation for String.charAt http://docs.oracle.com/javase/6/docs/api/java/lang/String.html#charAt(int) throws an error when you attempt to access out-of-bounds items in the String. Make sure that you check that you're not attempting to look beyond the length of the String before you go calling charAt all willy-nilly! If you're currently "considering" the 'T' in "INPUT" and you go trying to look at the next two characters, Java will complain.
Second, and this is more of a general thing (though it does need to be fixed in your code above); the '++' operator doesn't do what you appear to think it actually does. When you do this: in.charAt(ind++)=='H', you may think you're just checking on the value at the next index, but you're actually advancing the index at the same time! The '++' operator is very handy, but it has a side affect that trips up a lot of beginners: it assigns itself + 1 to itself! That means that if you're on the 'I' in "INPUT" and somewhere within your loop you call ind++ once, you'll be on 'P' at the next iteration of your loop! When you see '++' remember that you're changing the value of the variable.
Good luck!

Standard deviation of input numbers with JAVA

I am new to this place and in need of serious help. After spending 6 hours trying to figure out this, I am going insane and need help. Here is the question i am assigned.
Create the StandardDeviation project. Write a java program that reads a set of double data values. When all the values have been read, print out the count of the values, the average and the standard deviation.
I cannot find any commands that allow for a group of entered numbers at once and be read by JAVA. Could someone please help me get started or point to somewhere where i can find relative problems or examples. Thank you very much. All i know is that it supposed to start with
while (in.hasNextDouble())

I'm assuming this is homework.
You're going to want to look at java.util.Scanner, it will let you do while( Scanner.hasNextDouble() ) which you can then sum. You're also going to want to keep track of all the numbers so you should take a look at java.util.ArrayList.
Note: to use ArrayList properly you'll have to use the Double class, which can be treated almost exactly like a double primitive, or you can use arrays instead of ArrayList.

Take a look at the Scanner class. It can read input data and you can repeatedly call hasNextDouble and nextDouble on it to pull out the data.

From javaman (http://www.daniweb.com/members/javaman2/471995) I find a solution. It looks like the Scanner class provides capabilities in this area also.

For loop with no parameters in Java

I am looking at somebody else's code and I found this piece of code:
for (;;) {
I'm not a Java expert; what is this line of code doing?
At first, I thought it would be creating an infinite loop, but in the very SAME class this programmer uses
while(true)
Which (correct me if I'm wrong) IS an infinite loop. Are these two identical? Why would somebody change their method to repeat the same process?
Any insight would help,
Thanks!

Remember the three clauses of the for() are [1] initialization [2] termination and [3] increment. Since the termination clause is empty the loop never terminates. This is directly taken from C syntax.

Those two lines would have the same effect. I can't think of a good reason to use the first one unless you like to confuse people. I guess it's less characters.

they are entirely the same the only real difference would be either preference (the for construct can be typed marginally faster)
or the for indicates that is is some iteration that is broken out of by a break or return and a while loop indicates a repeating section of the same thing until a meaningful result appears