fork download
copy 
  1. import java.util.ArrayList;
  2. import java.util.Date;
  3. import java.util.List;
  4. import java.util.Map;
  5. import java.util.stream.Collectors;
  6. import java.util.function.*;
  7. import java.util.stream.*;
  8. import static java.util.stream.Collectors.*;
  9.  
  10. class LambdaTest {
  11.     public static void main(String[] args) {
  12.         List<Emp> list = new ArrayList<>();
  13.  
  14.         Dept dept1 = new Dept(1);
  15.         Dept dept2 = new Dept(2);
  16.         Dept dept3 = new Dept(3);
  17.  
  18.         list.add(new Emp(dept1, 500));
  19.         list.add(new Emp(dept1, 1000));
  20.         list.add(new Emp(dept1, 1500));
  21.         list.add(new Emp(dept1, 2000));
  22.  
  23.         list.add(new Emp(dept2, 1500));
  24.         list.add(new Emp(dept2, 2000));
  25.         list.add(new Emp(dept2, 2500));
  26.         list.add(new Emp(dept2, 3000));
  27.  
  28.         list.add(new Emp(dept3, 0));
  29.         list.add(new Emp(dept3, 100));
  30.         list.add(new Emp(dept3, 200));
  31.         list.add(new Emp(dept3, 500));
  32.  
  33.         new LambdaTest().rankedBySalAndFilter(list);
  34.     }
  35.  
  36.  
  37.     public static <T, A, R> Collector<T, ?, R> filtering(Predicate<? super T> predicate, Collector<? super T, A, R> collector) {
  38.         BiConsumer<A, ? super T> downstream = collector.accumulator();
  39.         return Collector.<T, A, R>of(collector.supplier(),
  40.                 (a, t) -> {if (predicate.test(t)) downstream.accept(a, t);},
  41.                 collector.combiner(), collector.finisher(),
  42.                 collector.characteristics().stream().toArray(Collector.Characteristics[]::new));
  43.     }
  44.  
  45.     void rankedBySalAndFilter(List<Emp> list) {
  46.         Map<Dept, Long> map = list.stream()
  47.         	.filter(emp -> emp.sal > 1000)
  48.             .collect(groupingBy(emp -> emp.dept, counting()));
  49.  
  50.         System.out.println(map);
  51.     }
  52.  
  53.     static class Emp {
  54.         Emp(Dept dept, Integer sal) {
  55.             this.dept = dept;
  56.             this.sal = sal;
  57.         }
  58.  
  59.         Integer empno;
  60.         Dept dept;
  61.         String ename;
  62.         String job;
  63.         Integer mgr;
  64.         Date hiredate;
  65.         Integer sal;
  66.         Integer comm;
  67.     }
  68.  
  69.     static class Dept {
  70.         Dept(Integer deptno) {
  71.             this.deptno = deptno;
  72.         }
  73.  
  74.         Integer deptno;
  75.         String dname;
  76.         String loc;
  77.  
  78.         @Override
  79.         public String toString() {
  80.             return "deptno" + deptno;
  81.         }
  82.     }
  83. }
  84.  
Success #stdin #stdout 0.23s 321024KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
{deptno2=4, deptno1=2}
https://ideone.com/EmTrXE
language:
Java (HotSpot 12)
created:
8 years ago
visibility:
secret

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!