Java8特性之用Stream流代替For循环操作详解

public class Student {

     private String name;

     private int age;

     public String getName() {

         return name;

     }

     public void setName(String name) {

         this .name = name;

     }

     public int getAge() {

         return age;

     }

     public void setAge( int age) {

         this .age = age;

     }

}

List<Student> list= new ArrayList<>();

Student s1= new Student();

s1.setName( "张三" );

s1.setAge( 18 );

list.add(s1);

Student s2= new Student();

s2.setName( "李四" );

s2.setAge( 22 );

list.add(s2);

//for循环

for ( int i= 0 ;i< list.size();i++){

     System.out.println(list.get(i));

}

//增强for循环

for (Student student: list){

     System.out.println(student);

}

//迭代器

Iterator<Student> iterator = list.iterator();

while (iterator.hasNext()){

     System.out.println(iterator.next());

}

//遍历List集合

  list.stream().forEach(str->{

     System.out.println(str.getName()+ ":" +str.getAge());

  });

  //过滤 把名字为李四的过滤掉

  list.stream().filter(str -> ! "李四" .equals(str.getName())).forEach(str -> {

      System.out.println(str.getName()+ ":" +str.getAge());

  });

   //操作对象，拼接

//String collect=list.stream().map(student->student.getName()).collect(Collectors.joining(",","前","后"));

// System.out.println(collect);

//声明一个条件 学生年龄大于18

Predicate<Student> pred = (student) -> student.getAge() > 18 ;

//调用方法

selectStudent(list,pred);

private static void selectStudent(List<Student> list, Predicate<Student> pred) {

        System.out.println( "选出年龄大于18的学生：" );

        list.forEach(student -> {

            if (pred.test(student)){

                System.out.println(student.getName()+ ":" +student.getAge());

            }

        });

    }

//java 8 stream操作 嵌套循环

         List<Student> list = list1.stream().filter(student1 -> list2.stream()

                 .anyMatch(studnet2 -> student1.getName().equals(studnet2.getName()) ))

                 .collect(Collectors.toList());

         System.out.println( "stream操作筛选后的结果" + list.get( 0 ).getName());