How to compare an array with an new created List java

Question

i have a String array with information like this:

name          street         streetnumber         City      house     flat
jetsons     jetstreet        12                  london       yes      no
jetsons     jetstreet        10                  washingston  n        y
jetsons     jetstreet        10                  washingston  n        y
jetsons     jetstreet        10                  washingston  yes      no 
ALF         alfStreet         3                  Shanghai      y        y

...and so on

now the exercise is to create an new list with unique data which is analyzed.

livingDataArray analyzedDataList

while(livingDataArray=reader.readLine() != null){
        street = livingDataArray[1];
        streetNumber = livinDataArray[2];
        city = livingDataArray[3;]

    if(analyzedDataList.isEmpty()) {
        createNewEntry in analyzedDataList(); // that line is fine. ;)
    } else {
        int analyzedDataSize = analyzedData.size();
        for (int i = 0; i <= analyzedDataSize; i++){

                  if(analyzedData.get(i)[1] == street && 
                    analyzedData.get(i)[2] == streetNumber &&
                    analyzedData.get(i)[3] == city ) {

                   categorize(); // this line is fine also
                   addToAnalyzedData();
                  break;
                  } else if (!(analyzedData.get(i)[1] == street && 
                    analyzedData.get(i)[2] == streetNumber &&
                    analyzedData.get(i)[3] == city) && (i+1 ==
                    livingData.size())) {

                             categorize();
                             addToAnalyzedData();
                             break;
                    }


             }
        }
}

My question is that efficient enough to use it for really big data? Like 100.000 rows and more? Because I'm not about the if else statements. Could anybody help me?

This is not really Java. Some statements are invalid. You have an assignment in a comparison without parentheses, and you compare strings with `==` . Why don't you show code that compiles properly? Also, you should show the definitions of things that you are using. — RealSkeptic, Oct 05 '15 at 16:04

score 0 · Accepted Answer · edited May 23 '17 at 11:44

String comparison works via equals, not == (How do I compare strings in Java?). Next point: This looks like the implementation in java of a plain SELECT DISTINCT * FROM someWhere-statement in SQL. So why not simply outsource the code to a database? If that's not possible, a Set would be most likely the most efficient collection. Though i'd recommend SQL to improve performance a lot and save resources on your local PC. One final note: Modifying data in a loop over the same data like here:

int analyzedDataSize = analyzedData.size();
for (int i = 0; i <= analyzedDataSize; i++){
    ...
        addToAnalyzedData();

is extremely prone to bugs/exceptions. For e.g. you're retrieving and modifying a collection in the loop mentioned above, without updating the size of the collection. In this example, this behavior won't do any damage, but you should handle this rather carefully.

How to compare an array with an new created List java

1 Answers1