【java8】stream的map和filter怎么混用？

Question

 List<SoReturnPicVO> collect = picList.stream().filter(x -> x.getType() == 1).collect(Collectors.toList());
            List<String> collect2 = collect.stream().map(x -> x.getPicUrl()).collect(Collectors.toList());

我要将实体里的一个字段取出来List-String,但是要根据另一个字段进行判断，我写成了两句，请问怎么能把这两句合并一下，写成一句

Answer 1

 picList.stream().filter(x -> x.getType() == 1).map(x -> x.getPicUrl()).collect(Collectors.toList());

Answer 2

 public class UserModel {

    private String name;

    public UserModel(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "UserModel{" +
                "name='" + name + '\'' +
                '}';
    }

}

         UserModel userModel1 = new UserModel("1");
        UserModel userModel2 = new UserModel("2");
        UserModel userModel3 = new UserModel("3");

        List<UserModel> userModelList = new ArrayList<>();
        userModelList.add(userModel1);
        userModelList.add(userModel2);
        userModelList.add(userModel3);

        List<String> names = userModelList.stream().filter((item) -> {
            String name = item.getName();
            return Integer.valueOf(name) > 1;
        }).map(UserModel::getName).collect(Collectors.toList());
        System.out.println(names);

Answer 3

这个是先filter在map的

 List<String> collect2 = collect.stream().filter(x -> x.getType() == 1).map(x -> x.getPicUrl()).collect(Collectors.toList());

先map在filter

 List<SoReturnPicVO> collect2 = collect.stream().map(x -> {
                                                                                                                    SoReturnPicVO so = new  SoReturnPicVO();
                                                                                                                    so.setPicUrl( x.getPicUrl());
                                                                                                                        so.setType( x.getType());
                                                                                                                    return so;
                                                                                                            })
                                                                                                .filter(x -> x.getType() == 1).collect(Collectors.toList());

这个时候集合里面是SoReturnPicVO，SoReturnPicVO对象里面只设置图片和类型两个字段的值。