CODEWITHSUNDEEP
javaoptimization
Sravan2023
Sravan2023

Reputation: 176

Java method Optimization

I am writing some java code i wrote a method and for the test input it is taking morethan 5sec's to execute I really really wanna keep it less than 5sec can anyone suggest me how i can optimize my method

private static String getShortestSub(ArrayList<String> paraWordsList,
        ArrayList<Integer> paraWordsIndexes,
        ArrayList<Integer> lowFreqIndexes) {

    long d = System.currentTimeMillis();
    // Finding the substring
    int startTxtIndex = 0, endTxtIndex = 0;
    int tempLength = paraWordsList.size();
    for (int i = 0; i < lowFreqIndexes.size(); i++) 
    {
        int point = lowFreqIndexes.get(i), startIndex = 0;
        HashSet<String> frame = new HashSet<String>();


        // index is the indexes of paraWordsIndexes
        startIndex =paraWordsIndexes.indexOf(point);
        for (int index = paraWordsIndexes.indexOf(point); index >= 0; index--) 
        {
            if (frame.add(paraWordsList.get(paraWordsIndexes.get(index))))
            {
                startIndex = index;
                if (frame.size() == K
                        || (paraWordsIndexes.get(startIndex) - point) >= tempLength) 
                    index = -1;                 
            }
        }
        frame.clear();

        for (int start = startIndex, index = startIndex; start <= paraWordsIndexes
                .indexOf(point) && index < paraWordsIndexes.size(); index++) 
        {
            int tempStart = paraWordsIndexes.get(start), tempEnd = paraWordsIndexes.get(start);
            int currIndex = paraWordsIndexes.get(index);
            String word = paraWordsList.get(currIndex);
            if ((tempStart - point) >= tempLength)          break;
            if ((tempStart - currIndex) >= tempLength)      break;
                    frame.add(word);
            if (frame.size() == K) 
            {
                tempEnd = currIndex;
                int newLength;
                if ((newLength = tempEnd - tempStart) > 0)
                    if (tempLength > newLength) 
                    {
                        tempLength = newLength;
                        startTxtIndex = tempStart;
                        endTxtIndex = tempEnd;
                        if (K == (tempLength+1)) {
                            i = lowFreqIndexes.size();
                            break;
                        }
                    }
                frame.clear();
                tempStart = paraWordsList.size();
                start++;
                index = start - 1;
            }
        }
        frame.clear();
        System.out.println(System.currentTimeMillis() - d);
    }

    String[] result = paraText.split(" ");
    ArrayList<String> actualParaWordsList = new ArrayList<String>(
            Arrays.asList(result));

    return textCleanup(actualParaWordsList.subList(startTxtIndex,
            endTxtIndex + 1).toString());
}

Upvotes: 0

Views: 250

Answers (3)

c.s.
c.s.

Reputation: 4816

As a first optimization you could remove redundant calls to indexOf()

During the outer loop point variable does not change so the first call of indexOf() is the only one that is actually required.

// index is the indexes of paraWordsIndexes
startIndex =paraWordsIndexes.indexOf(point);

Introduce instead a new variable that would store the result of indexOf() and would not change inside the loop

int pointLFIndex = paraWordsIndexes.indexOf(point); // new variable. should not change
startIndex = pointLFIndex;

Then change all occurences of indexOf(point) to the above variable.

// you don't need this. change to for (int index = pointLFIndex; ...);
for (int index = paraWordsIndexes.indexOf(point); index >= 0; index--)  

// use for (int start = ...; start <= pointLFIndex ...; index++) {
for (int start = ...; start <= paraWordsIndexes.indexOf(point) ...; index++) {

indexOf() searches your array list linearly. Especially the second occurence is executed on every loop iteration, so it would be a killer for large lists

If the above doesn't help, I don't understand why you don't edit your question to add a simple test case since so many people have asked you too (including myself).

A simple scenario like this:

Input text: "Some words are larger while some other words are smaller"

paraWordsList: contains the string split of the above text e.g. {"Some", "words", ...}

paraWordsIndexes: contains the indexes of blah blah e.g. {0, 3}

lowFreqIndexes: contains blah blah e.g. {0, 1}

Expected output: it should return {value} but not {other_value}

Upvotes: 2

Matthew Herbst
Matthew Herbst

Reputation: 31983

Well, it would help if you didn't have nested loops, and, it would also help if you could minimize the number of if statements within each loop (especially if you have nested loops).

Can you explain what you are trying to do? Your code isn't totally obvious, and maybe there is a way to do it completely different from your approach.

Upvotes: 0

Ernesto Campohermoso
Ernesto Campohermoso

Reputation: 7371

Your code appears to be complex ( for - if - for) in this case the best way to optimize it is using a profiler for check where is the code that is taking more time in the execution process.

Since you don't specify your IDE, y will try to suggest some interesting tools:

https://profiler.netbeans.org/ http://www.eclipse.org/tptp/

Best regards

Upvotes: 1

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