Load factor in collections
HashMap hashMapName = new HashMap(5, .9);
//The 5 sets the initial element capcaity.
//The .9 is the load factor.
// The default load factor is .75.
I was reading above code. I have not understood what it mean by loead factor. please advise
Any ideas, sample code, links, resources highly appreciated. thanks in advance
//The 5 sets the initial element capcaity.
//The .9 is the load factor.
// The default load factor is .75.
I was reading above code. I have not understood what it mean by loead factor. please advise
Any ideas, sample code, links, resources highly appreciated. thanks in advance
It means that if you initially specified 100 elements in HashTable, when you fill in this
HashTable to 75 (assuming loadfactor is 0.75) then virtual machine will automaticalluy incerease its capacity,
so that certain share of it is emapty and ready to be filled in when you add next element
HashTable to 75 (assuming loadfactor is 0.75) then virtual machine will automaticalluy incerease its capacity,
so that certain share of it is emapty and ready to be filled in when you add next element
ASKER
>>. Higher values decrease the space overhead but increase the lookup cost (reflected in most of the operations of the HashMap class, including get and put). The expected number of entries in the map and its load factor should be taken into account when setting its initial capacity, so as to minimize the number of rehash operations
>>virtual machine will automaticalluy incerease its capacity,
If i say .95 does not it increase as much as when i say say .75
can you please elaborate on this
>>virtual machine will automaticalluy incerease its capacity,
If i say .95 does not it increase as much as when i say say .75
can you please elaborate on this
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The load factor is a measure of how full the hash table is allowed to get before its capacity is automatically increased.
http://www.coderanch.com/t/521319/java/java/HashMap-load-factor
http://stackoverflow.com/questions/434989/hashmap-intialization-parameters-load-initialcapacity
As a general rule, the default load factor (.75) offers a good tradeoff between time and space costs. Higher values decrease the space overhead but increase the lookup cost (reflected in most of the operations of the HashMap class, including get and put). The expected number of entries in the map and its load factor should be taken into account when setting its initial capacity, so as to minimize the number of rehash operations. If the initial capacity is greater than the maximum number of entries divided by the load factor, no rehash operations will ever occur.