Java thread - combiner collector

Why the following code:   

StringBuilder sb22 = IntStream
     .range(1, 101)
     .filter(x -> x > 50)
     .boxed()
     .parallel()
     .collect(// object that is used in accumulator to do accumulating on
              StringBuilder::new, 
              // use object from above and call append on it with each stream element as argument
              (sb, a) -> sb.append(":" + a),  
              // (executes only when using parallel!)
              (sb1, sb2) -> { 
                     System.out.println(Thread.currentThread().getId() + "  " + "sb1=" + sb1 + " AND " + "sb2=" + sb2); 
                     sb1.append("-"+sb2);
              });

produces this result:

------------------:51:52:53-:54:55:56-:57:58:59-:60:61:62-:63:64:65-:66:67:68-:69:70:71-:72:73-:74:75-:76:77:78-:79:80:81-:82:83:84-:85:86:87-:88:89:90-:91:92:93-:94:95:96-:97:98-:99:100

shouldn't you separate ( ------------------) from the output first?

In addition, I realized that the assembler in the assembly could potentially be disabled, so you can use :76:77:78-:79:80:81, for example , instead . :63:64:65-:79:80:81?

UPDATE (after @Holger's answer)

This is a tree generated using the code associated for this case:

                                                                                                                                                    [51..100]                                                                                                                                                     
                                                                        _________________________________________________________________________________/\______________________________________________________________________                                                                                 
                                                                       |                                                                                                                                                         |                                                                                
                                                                    (empty)                                                                                                                                                 [51..100]                                                                             
                                    ___________________________________/\__________________________________                                                                              ________________________________________/\______________________________________                                         
                                   |                                                                       |                                                                            |                                                                                |                                        
                                (empty)                                                                 (empty)                                                                     [51..75]                                                                         [76..100]                                    
                ___________________/\______________                                     ___________________/\______________                                       ______________________/\________________                                         ______________________/\________________                       
               |                                   |                                   |                                   |                                     |                                        |                                       |                                        |                      
            (empty)                             (empty)                             (empty)                             (empty)                              [51..62]                                 [63..75]                                [76..87]                                 [88..100]                  
        _______/\______                 ___________/\______                     _______/\______                 ___________/\______                      ________/\_______                   _____________/\_______                       ________/\_______                   _____________/\_______              
       |               |               |                   |                   |               |               |                   |                    |                 |                 |                      |                     |                 |                 |                      |             
    (empty)         (empty)         (empty)             (empty)             (empty)         (empty)         (empty)             (empty)             [51..56]          [57..62]          [63..68]               [69..75]              [76..81]          [82..87]          [88..93]               [94..100]         
    ___/\__         ___/\__         ___/\__         _______/\__             ___/\__         ___/\__         ___/\__         _______/\__              ___/\___          ___/\___          ___/\___          ________/\__               ___/\___          ___/\___          ___/\___          ________/\___         
   |       |       |       |       |       |       |           |           |       |       |       |       |       |       |           |            |        |        |        |        |        |        |            |             |        |        |        |        |        |        |             |        
(empty) (empty) (empty) (empty) (empty) (empty) (empty)     (empty)     (empty) (empty) (empty) (empty) (empty) (empty) (empty)     (empty)     [51..53] [54..56] [57..59] [60..62] [63..65] [66..68] [69..71]     [72..75]      [76..78] [79..81] [82..84] [85..87] [88..90] [91..93] [94..96]     [97..100]     
                                                            ___/\__                                                                 ___/\__                                                                         ___/\___                                                                         ____/\__     
                                                           |       |                                                               |       |                                                                       |        |                                                                       |        |    
                                                        (empty) (empty)                                                         (empty) (empty)                                                                [72..73] [74..75]                                                                [97..98] [99..100]
+6
source share
3 answers

, - , Stream [1, 101] , . , , , , , , .

, , , . , , , , . , - , , , (, List StringBuilder) , .

, , , . (sb1, sb2) -> sb1.append(sb2) (sb1, sb2) -> sb1.length()==0? sb2: sb1.append(sb2)

Q & A, " Java" .

+3

StringBuilders x < 51. - , , , . , .

, , sb2.append(sb1), , , .

+2

sb1.append("-"+sb2), . , , , /.

combiner , , StringBuilder::append lambda:

(left, right) -> left.append(right)

, ( , ). , HashSet ( ), . , java-9 Set.of, run to run.

+2

All Articles