Pig Latin Translator Program (English sentence input)

Question

I am currently writing a Java program for AP computer science, with the goal to translate an English sentence into Pig Latin. My full program code is http://pastebin.com/PJgpveAh

But the main issue (I believe) is the

    public static String pigLatSent(String sent)
{
    sent.trim();
    String finalSent="";
    ArrayList<Integer> spaceIndexes= new ArrayList<Integer>();
    spaceIndexes.add(0);
    for(int i=0;i<sent.length();i++)
    {
        if(sent.charAt(i)==' ')
        {
            spaceIndexes.add(i);
        }
    }
    for(int i=0;i<spaceIndexes.size()-1;i+=2)
    {
        int value=spaceIndexes.get(i);
        int value1=spaceIndexes.get(i+1);
        finalSent+=pigLat(sent.substring(value, value1))+" ";
    }
    return finalSent;
}

Upon the input "hello how are you" The program returns "Your translated sentence is ellohay are ay " when it should be "Your translated sentence is "Your translated sentence is ellohay owhay areway ouyay "

There must be something wrong with the indexing of the spaces. I am having a mental block.

Answer 1

There are two problems:

1. You are skipping every second word: i+=2. This is fixed by doing i++ instead.

2. Once 1. is fixed, you are skipping the last word, because the list of indexes does not include the end of the string. This is fixed by doing spaceIndexes.add(sent.length()); after the first loop (which is symmetrical to spaceIndexes.add(0); before the loop).

Then, there are a bunch of other minor problems:

• sent.trim() doesn't do what you expect. String is immutable in Java, so this expression returns the new trimmed string, which is just ignored. It sould be sent = sent.trim(); (or use a different variable for the result and use it afterwards).

• The pigLat() function receives the words (except the first one) including the leading space, e.g. it receives the following inputs in sequence: "hello", " how", " are", " you". This must be taken care of by the pigLat() implementation.

• Concatenating strings in a loop is a known antipattern — see Schlemiel the Painter's algorithm. Please consider using StringBuilder instead.