java - Java 8 - 流 - 收集时的值更新

Question

在扩展上一个问题Java 8 - Calling a multi argument method from Collection.stream.map()中，我们如何在处理collect()后收集时更新值stream().map()？

String designation = "Engineer";
String preFix = "PRE_FIX";
List<String> names = new ArrayList<>();
names.add("ABC");
names.add("DEF");
names.add("GHI");
System.out.println(
    names.stream()
         .map(name -> 
              MyClass.createReport(name, designation))
         .collect(ArrayList::new, ArrayList::add, ArrayList::addAll));

---

public static String createReport(String name, String designation) {
   return ("Name:" + name + " - Designation:" + designation);
}

输出：

[Name:ABC - Designation:Engineer, Name:DEF - Designation:Engineer, 
 Name:GHI - Designation:Engineer]

预期的：

[PRE_FIX->Name:ABC - Designation:Engineer, PRE_FIX->Name:DEF - 
 Designation:Engineer, PRE_FIX->Name:GHI - Designation:Engineer]

标签： javajava-8java-stream

Answer 1

使用另一个map()

System.out.println(
      names.stream()
           .map(name -> FolderDiffGenerator.createReport(name, 
                        designation))**
           .map(result -> preFix + "->" +result)**
           .collect(ArrayList::new, ArrayList::add, ArrayList::addAll));