package com.demo;
 
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;
 
public class Test6 {
 
  public static void main(String[] args) {
    List<Student> stuList = new ArrayList<Student>();
    Student st1 = new Student("123","aaa");
    Student st2 = new Student("234","bbb");
    Student st3 = new Student("345","ccc");
    Student st4 = new Student("345","ccc");
    stuList.add(st1);
    stuList.add(st2);
    stuList.add(st3);
    stuList.add(st4);
    //1.提取出list对象中的一个属性
    List<String> stIdList1 = stuList.stream()
        .map(Student::getId)
        .collect(Collectors.toList());
    stIdList1.forEach(s -> System.out.print(s+" "));
    System.out.println();
    System.out.println("----------");
    
    //2.提取出list对象中的一个属性并去重
    List<String> stIdList2 = stuList.stream()
        .map(Student::getId).distinct()
        .collect(Collectors.toList());
    stIdList2.forEach(s -> System.out.print(s+" "));
    /*	结果：
      123 234 345 345  
      ----------
      123 234 345 
    */
  }
}