Performance of algorithm using Stringbuilder vs Integer array

Question

I am trying to form a string ( of length 10,000 ) with 1's and 0's based on a certain condition 'valid'.

Although I am able to do this, I am concerned about the performance and would need some help to decide on which of the below two methods would be better performant.

Method 1 (Using Stringbuilder)

StringBuilder output = new StringBuilder(); 

    for( int i = 0; i < 10000; i++ )
        {
            if ( valid )
            {
                output.append( "1" );
            }
            else
            {
                output.append( "0" );
            }
        }

Method 2 (Using integer array)

int[] gridArray = new int[ 10000 ];

   for( int i = 0; i < 10000; i++ )
    {
        if ( valid )
        {
            gridArray[i] = 1;
        }
    }

        //Convert grid array to string output

Also, how best to convert the integer array to a String?

A slightly more efficient structure you could use would be a BitSet. — OldCurmudgeon
– OldCurmudgeon, Commented Mar 21, 2018 at 10:05
How exactly does BitSet make it more efficient to form a string with 1s and 0s? It still uses StringBuilder in toString(). — lexicore
– lexicore, Commented Mar 21, 2018 at 10:46

lexicore · Accepted Answer · 2018-03-21 10:45:42Z

2

If you really want to build a string with 1s and 0s of a known length then the most efficient would be probably to build a charater array and create a string out of it. Something along the lines:

char[] result = new char[10000];
for (int index = 0; index < result.length; index++) {
    result[index] = (index %2 == 0) ? '1' : '0';
}
String stringResult = new String(result);

StringBuilder (initialized with sufficient capacity) will probably have the same performance, so I'd actually took it. There is some minimal capacity, but it's not even worth mentioning.

Other structures suggested here (integer array or bitset) may be better to store your 1s and 0s, but they still need to be converted to a string. And that will probably require a StringBuilder anyway. BitSet, for instance, uses StringBuilder in its toString() method.

answered Mar 21, 2018 at 10:45

lexicore

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Comments

Suresh Atta · Accepted Answer · 2018-03-21 10:04:50Z

1

None of the above.

The best suitable class for you is BitSet.

This class implements a vector of bits that grows as needed. Each component of the bit set has a boolean value. The bits of a BitSet are indexed by nonnegative integers. Individual indexed bits can be examined, set, or cleared. One BitSet may be used to modify the contents of another BitSet through logical AND, logical inclusive OR, and logical exclusive OR operations.

By default, all bits in the set initially have the value false.

answered Mar 21, 2018 at 10:04

Suresh Atta

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1 Comment

lexicore Over a year ago

How exactly does BitSet make it more efficient to form a string with 1s and 0s?

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