CODEWITHSUNDEEP
javaandroidperformance
HimanshuR
HimanshuR

Reputation: 1428

which is better option?

i need to maintain a list containing two values of string type say v1,v2 for each key say k. What is a better option

  1. Hashmap with value containing a string containing v1 and v2 and using split() to retrive the correct value after selection.
  2. Hashmap with value containing array of two string variables

I am creating an android app, so just concern about performance. In second case i can access directly but each value will contain another array ( i dont know but it appears like a complicated way) , while in 1st case it will use split function on every access like v.split(",")[0]

Please guide me.

Map<String,String[]> listMap= new HashMap<String, String[]>();
Map<String,String> listMap1= new HashMap<String, String>();;

for (int i = 1; i < tl.getChildCount(); i++) {
    TableRow row = (TableRow) tl.getChildAt(i);
    COLOR_TABLE clr = (COLOR_TABLE) row.getTag();

    if (clr == COLOR_TABLE.green) {
        //comp
        String x1=listMap1.get( ((TextView) row.getChildAt(0)).getText());
        String x2=listMap.get( ((TextView) row.getChildAt(0)).getText());
        // now i have to add two string values in a list seperately
    }
}

Upvotes: 1

Views: 113

Answers (4)

Thomas Padron-McCarthy
Thomas Padron-McCarthy

Reputation: 27632

The string will be much slower than the array, and also have more complicated code. (With the caveat that it is hard to be sure about performance differences until one has actually measured it.)

But if it was me, I would use the simplest solution, and use an object. Later, if the program turns out to be too slow, and measurement shows this to be a performance bottleneck, I would consider other solutions.

Upvotes: 1

Joni
Joni

Reputation: 111219

Using an array or a custom class as the value would be the preferred approach from a design perspective. If you pack two strings into one separated by a character you need to make sure that the first string won't ever contain that same character, or you must use some kind of an escape mechanism to be able to include it.

If you are only worried about performance test all options and pick the best one. It's hard make predictions because the results will depend on the data you store and on how libraries have been implemented. For example, any structure that stores references to independent strings will potentially suffer a cache miss on access; if the string split or a similar method turns out to be cheaper than a cache miss it will be faster.

Upvotes: 0

luiso1979
luiso1979

Reputation: 918

Never abuse Strings! It may be slow at times and they are not made for that purpose.

You could use a generic Pair class if you want to do it more object oriented:

public class Pair<A, B> {

  public A first;
  public B second;

  public Pair(A first, B second) {
    this.first = first;
    this.second = second;
  } 
}

Of course you can do it better, with accessors and so.

Upvotes: 5

yilmazburk
yilmazburk

Reputation: 917

i think split function runs with O(string size) complexity but reach element of an array is a constant

Upvotes: 1

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