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标题: 聚合操作例子(oracle甲骨文官网示例) [打印本页]

作者: GuiTarvvm2098 时间: 2018-1-4 09:34
标题: 聚合操作例子(oracle甲骨文官网示例)
import java.lang.Iterable;
import java.lang.Number;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.function.BinaryOperator;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.function.Predicate;

public class BulkDataOperationsExamples {

public static void main(String... args) {

      // Create sample data

      List<Person> roster = Person.createRoster();

      // 1. Print names of members, for-each loop

      System.out.println("Members of the collection (for-each loop):");
      for (Person p : roster) {
         System.out.println(p.getName());
      }

      // 2. Print names of members, forEach operation

      System.out.println("Members of the collection (bulk data operations):");
      roster
         .stream()
         .forEach(e -> System.out.println(e.getName()));

      // 3. Print names of male members, forEach operation

      System.out.println(
         "Male members of the collection (bulk data operations):");
      roster
         .stream()
         .filter(e -> e.getGender() == Person.Sex.MALE)
         .forEach(e -> System.out.println(e.getName()));

      // 4. Print names of male members, for-each loop

      System.out.println("Male members of the collection (for-each loop):");
      for (Person p : roster) {
         if (p.getGender() == Person.Sex.MALE) {
            System.out.println(p.getName());
         }
      }

      // 5. Get average age of male members of the collection:

      double average = roster
         .stream()
         .filter(p -> p.getGender() == Person.Sex.MALE)
         .mapToInt(Person::getAge)
         .average()
         .getAsDouble();

      System.out.println(
         "Average age of male members (bulk data operations): " +
         average);
}
}

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