Stream Performance Comparison test

Test environment: JDK1.8.0_60, Guava-18.0.jar

Tomap

    public static void Demo1 () {int size = 50000;
        list<string> list = new arraylist<> (size);
        for (int i = 0; i < size; i++) {List.add (integer.tostring (i));
        } System.out.println ("size =" + size);
        Long Start2 = System.currenttimemillis ();
Map<integer, string> map3 = maps.newhashmapwithexpectedsize (size); for (int i = 0; i < size; i++) {//String string = List.get (i);//Map3.put (String.has
Hcode (), string);
        for (string string:list) {Map3.put (String.hashcode (), string);
        Long End2 = System.currenttimemillis ();

        System.out.println ("iterator---t =" + (END2-START2));
        Long start = System.currenttimemillis (); Map<integer, string> map = List.parallelstream (). Collect (Collectors.tomap (S-> s.hashcode (), S-
        > s));
   Long end = System.currenttimemillis ();     SYSTEM.OUT.PRINTLN ("Stream---t =" + (End-start));
        Long Start1 = System.currenttimemillis (); Map<integer, string> map1 = Maps.uniqueindex (list,//lists for value list new Com.google.common.base.Functi On<string, integer> () {@Override public Integer apply (String value) {//return value is
                    Key, the parameter is Value return Value.hashcode ();
        }
                });
        Long end1 = System.currenttimemillis ();
    SYSTEM.OUT.PRINTLN ("Guava---t =" + (END1-START1)); }

Note the map type generated by guava.
Test results:

Size = 5000
iterator---t =
---t =
guava---t =

size = 500000
iterator---t = 148< C5/>stream---t = 1533
Guava---t = 104

Filter

    public static void Demo2 () {int size = 5000;
        list<string> list = new arraylist<> (size);
        for (int i = 0; i < size; i++) {List.add (integer.tostring (i));
        } System.out.println ("Szie =" + size);
        Long Start2 = System.currenttimemillis ();
        List<string> List2 = lists.newarraylistwithcapacity (size);
            for (int i = 0; i < size; i++) {String string = List.get (i);
            if (integer.valueof (string)% 2 = 0) {list2.add (string);
        } Long End2 = System.currenttimemillis ();

        System.out.println ("iterator---t =" + (END2-START2));
        Long start = System.currenttimemillis (); List<string> List1 = List.parallelstream (). Filter (S-> integer.valueof (s)% 2 = 0). Collect (Coll
        Ectors.tolist ());
        Long end = System.currenttimemillis (); SYSTEM.OUT.PRINTLN ("Stream---t =" + (end-sTart)); }

Test results:

Szie = 5000
iterator---t =
---t =

Szie = 500000
iterator---t =
stream---t = 1 33

AnyMatch

    public static void Demo3 () {
        int size = 500000;
        list<string> list = new arraylist<> (size);
        for (int i = 0; i < size; i++) {
            List.add (integer.tostring (i));
        }

        System.out.println ("Szie =" + size);
        Long Start2 = System.currenttimemillis ();
        for (int i = 0; i < size; i++) {
            string string = List.get (i);
            if (String.endswith ("412347")) {break
                ;
            }
        }

        Long End2 = System.currenttimemillis ();
        System.out.println ("iterator---t =" + (END2-START2));

        Long start = System.currenttimemillis ();
        List.parallelstream (). AnyMatch (S-> s.endswith ("1234567"));
        Long end = System.currenttimemillis ();
        SYSTEM.OUT.PRINTLN ("Stream---t =" + (End-start));
    }

Test results:

Szie = 500000
iterator---t =
stream---t = 114