我应该从在Java中修改'object-argument'的方法返回'object-argument'吗？

Question

以下代码示例首选哪种样式？

1

class Player
{
    Player() { this.id = UID.generate(); }
}

void fillPlayerData(Player player, PlayerRequest playerRequest)
{
    player.name = playerRequest.name;
    ...    
}

或

Player fillPlayerData(Player player, PlayerRequest playerRequest)
{
    player.name = playerRequest.name;
    ...
    return player;    
}

2

void setErrors(Object object, List<Error> errors)
{
    object.status = Status.ERROR;
    ...
    object.addAll(errors);
}

或

Object setErrors(Object object, List<Error> errors)
{
    object.status = Status.ERROR;
    ...
    object.addAll(errors);
    return object;
}

更新： 哪一个更适合在RxJava中使用：

3

Single<Object> returnObject(Object object)
{
    return loadSingle
       .doOnSuccess(objectResponse -> fillData(object, objectResponse))
       .doOnError(e -> addErrors(object, e))
       .toCompletable()
       .andThen(Single.just(object));
}

4

Single<Object> returnObject(Object object)
{
    return loadSingle
       .map(objectResponse -> fillData(object, objectResponse))
       .onErrorReturn(e -> addErrors(object, e));
}

Answer 1

您拥有的方法类型基本上是修改参数。有三种情况可能

[案例1]传递的参数是（是）原始的

public void invoker(){
    int x = 20;
    int increment = 30;
    x = getIncrementedValue(x,increment);
}
public int getIncrementedValue(int x, int inc){
     return x+inc;
}

[案例2]传递的参数是（不）可变的

public void invoker(){
    String x = "kk";
    String y = nits;
    x = getAppendedString(x,y);

}
public String getAppendedString(String a, String b){
     a = a.append(b); // as Strings are non mutable hence this is not changed on the original passed object. The assignment of a also does not make any difference as it's local variable.
  return a
}

[案例3]传递的参数是（是）可变对象引用。

 public void invoker(){
    Student s = new Student();       
    promoteStudent(s);
 }
public void promoteStudent(Student s){
     s.standard++;
     // No need to return the object reference as same object has been modified and reference of the same is present with the invoker.
}

public class Student{
    int standard = 1;
}

修改 注释中提到的另一个用例。在链接的情况下，返回相同的对象很有用。

 public class Student{
       String name;
       int roll;
       int standard;
       public Student setName(String n){ this.name =n; return this;}
       public Student setRoll(int n){ this.roll =n; return this;}
       public Student setStandard(int n){ this.standard =n; return this}
      public int getFees(){
           return standard*2;
      }
}
...
public void someMethod(Student s){

 Int fees = s.setName("KK").setRoll(30).setStandard(10).getFees();
  // Other lines of code ..
 }