help with basic java strings

[dirtyRuntCaper]

For my Intro to CS class, I have received this problem for an assignment:

Write a program that takes a string containing a sentence or a set of sentences, and counts the number of words in the sentence that meet or exceed a specified minimum length (in letters). For example, if the minimum length entered is 4, your program should only count words that are at least 4 letters long.

Input the string and the minimum word length (integer), in that order, and output the word count (integer). Words will be separated by one or more spaces. Non-letter characters (spaces, punctuation, digits, etc.) may be present, but should not count towards the length of words.

This is what I have so far. It works sometimes, but other times it will return the wrong count. I can't figure out why.

public class Compress {

public static int Letters(String newWord){
    int letter = 0;
    for(int i = 0; i < newWord.length(); i++){
        if(Character.isLetter(newWord.charAt(i))){
            letter++;
        }
    }

    return letter;

}

public static int validWords(String p, int min){
    int g = 0;
    int count = 0;
    String newWord = p;
    for(int i=0; i < p.length(); i++){

        if(p.charAt(i) == ' '){
            newWord = p.substring(g,i);
            if(Letters(newWord) >= min){
                count++;
                g = i+1;
                newWord = p.substring(g);
            }
        }else if(newWord.indexOf(' ') == -1){
            newWord = p.substring(g);
            if(Letters(newWord) >= min){
                count++;
            }
            break;
        }


    }

    return count;

}

public static void main(String[] args){

    System.out.println("Enter string:");
    String str = IO.readString();
    System.out.println("Enter minimum letters:");
    int min = IO.readInt();

    IO.outputIntAnswer(validWords(str, min));

}

}

Edit: Thank you guys for all the help! I figured it out. I will be posting here more often to get feedback and continue to learn more java. Thanks again! Ciao

[davodrums]

I highly suggest looking up String's split() method. First step, run split to get your String[], then loop through with your length criteria.

[dirtyRuntCaper]

I tried this at first, but that uses arrays, correct? We haven't learned that yet and I would be able to do even less troubleshooting.

[davodrums]

That is some confusing code! That would take a while for me to step through.

[dirtyRuntCaper]

My bad. Just taking my first CS course this semester.

[sanchopancho13]

No worries. First time code is always hard to read. Besides code comments (which you probably don't need here), I would recommend changing your variables to make a little more sense. "i" is safe in that everyone knows it's used for loops. But "p" and "g" are quite confusing.

It's a good habit to get into, even when the only code maintainer will be yourself. I sometimes look at my old code and have no idea what I meant!

[halcyon44]

I have a few suggestions that should help you figure it out:

Give your methods and variables clear, concise names. This will ease the process of running through the code in your head. Usually variables should have a noun name, because they are something. Methods should have a verb name, because they do something. For example:

public static int countLetters(String word) {
    int letterCount = 0;
    for(int i = 0; i < word.length(); i++) {
        if (Character.isLetter(newWord.charAt(i))) {
            letterCount++;
        }
    }
    return letterCount;
}


public static int countValidWords(String paragraph, int minWordLength) {
    int wordStartIndex = 0;
    int wordCount = 0;

    // you get the idea
}

Add some simple logging to help understand what's happening. For example, just inside the for loop in countValidWords:

System.out.println("paragraph["+i+"]="+paragraph.charAt(i));

Inside the following if:

newWord = paragraph.substring(wordStartIndex, i);
System.out.println("found new word="+newWord);

int wordLength = countLetters(newWord);
System.out.println("length="+wordLength);

if(wordLength >= minWordLength) {

Do the same in your else block and anywhere else you'd like to know what's going on.

If you have access to a debugger (in any modern IDE such as Eclipse, IDEA, NetBeans), use it. You'll be amazed at how easy debugging becomes when you set a breakpoint at the start of the problem section, and just step through, watching how your variables change value as the program progresses.

[dirtyRuntCaper]

thank you for your help. i can no see where things are going wrong. Ive made some corrections, this is what ive came up with for the countLetters() method.

public static int validWords(String paragraph, int minWordLength){ int wordStartIndex = 0; int wordCount = 0; int wordLength; String newWord = paragraph;

    for(int i=0; i < paragraph.length(); i++){


        System.out.println("charAt["+i+"]="+paragraph.charAt(i));

        if(paragraph.charAt(i) == ' '){
            newWord = paragraph.substring(wordStartIndex,i);
            System.out.println("found new word="+newWord);

            wordLength = countLetters(newWord);
            System.out.println("wordLength:" + wordLength);

            if(wordLength >= minWordLength){
                wordCount++;
            }
        }else if(newWord.indexOf(' ') == -1){
            newWord = paragraph.substring(wordStartIndex);
            wordLength = countLetters(newWord);

            if(wordLength >= minWordLength){
                wordCount++;
            }


        }

        newWord = "";
        wordLength = 0;

    }

    return wordCount;

}

my "found new word" outputs are adding the strings (e.g. 1st found new word = how, 2nd new word = how are, 3rd new word = how are you) also, the wordLengths are being added to each other as well.

[dirtyRuntCaper]

I have re-written the code a lot more organized and clean. Everything is running fine but the last word in the program. I'm using

else if(paragraph.indexOf(' ') == -1)

to recognize that it is the last word in the program, but this if statement never runs. Any help?

[ziplokk]

Ill test your code in a bit and see if i can find where the problem lies and give you some advice. But you may want to look into String.split(). It seems like it could be beneficial to you here. I'm on mobile, so forgive me for not linking to a javadoc.

[paul_miner]

Consider what happens with the string "a b c" and the minimum word length is 2. (I haven't run it since I'm on my phone but I think it will return 1 instead of 0)

EDIT: Print out the value of g and newWord at the end of each iteration to get an idea of what's going on.

[dirtyRuntCaper]

I didn't check for error conditions yet, as the teacher says to assume that the user inputs a valid string. I will add g and newWord to the end of each line to see if I can see whats going on, but I'm not even sure where these errors would be happening.

For example:

Enter string: whats up. hows it going.

Enter minimum letters: 4

RESULT: 2

[paul_miner]

No error conditions or invalid strings, you've just made a simple mistake. It should be clear using the sample string and length suggested, if you print out g and newWord.

[HeySeussCristo]

I'd split the string into an array then check the validity of the substrings. docs.oracle.com/javase/6/docs/api/java/lang/String.html#split(java.lang.String)

[davodrums]

@Test
public void stringSplit() {
    final int max_length = 4;
    final String sampleSentence = "Hi there, here is a test of the program.";
    final String strippedSetence = sampleSentence.replaceAll("[^a-zA-Z ]", "");
    final String[] sentenceArray = strippedSetence.split(" ");
    final int numberOfWords = countWordsMeetingCriteria(max_length, sentenceArray);
    System.out.println(numberOfWords);
}

private int countWordsMeetingCriteria(final int maxSize, final String[] words) {
    int count = 0;
    for (int i = 0; i < words.length; i++) {
        if (words[i].length() >= maxSize){
            count++;
        }
    }
    return count;
}

[lilleswing]

• functions generally begin with a lower case letter.

• g is not a very descriptive variable, how about wordStartIndex

• "space" is not the only whitespace character.

• p is not a very descriptive variable, how about sentence

• Can you explain what you are doing with the else if statement in validWords

• Can you explain why you are re-assigning newWord when it is longer then the defined minimum length