writing a function that needs Class.class as a parameter in java

Question

I want to write a function that needs a Class.class as a parameter

example:

class MyObject{


  public whatTypeGoesHer MyFunction(something1, something2){
//do something with parameters
}

}

class MyObject1{
      MyObject object = new MyObject();

       MyObject1 object2 = object.MyFunction(MyObject1.class,something else);

}

this type of invokation is what i want to achieve, how do i define "MyFunction" to accept this type of parameter?

what should be instead of "whatTypeGoesHere"?

EDIT:

Let me rephrase the question

i want to deserialize classes from JSON using GSON however, i find myself writing the exact same methods in every class i want to deserialize with the difference of the class name

this is my code:

public static User fromJSON(String json, Class<?> className) {
    GsonBuilder builder = new GsonBuilder();
    builder.serializeNulls();
    User g1 = builder.create();
    User user = g1.fromJson(json, className.getClass());
    return user;
}

and its invokation in the used class

User user =   User.fromJSON(json,User.class);

I want to put the "fromJSON" method to some utils class, because in every class it is EXACTLY the same,with the difference of the class name that it returns

how do i do that?

Note that according to Java Coding style methods should start using lower letter. — Damian Leszczyński - Vash, Aug 01 '13 at 13:50

Rohit Jain · Answer 1 · 2013-08-01T13:50:55.600

10

You need a parameter of type Class<?>:

public void myFunction(Class<?> something1, SomeOtherType something2)

You should go through Reflection Tutorial

edited Aug 01 '13 at 13:50

answered Aug 01 '13 at 13:44

Rohit Jain

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Parameter, not argument. The argument is `MyObject1.class`. – Jon Skeet Aug 01 '13 at 13:46
1

PS. This will not compile. – Damian Leszczyński - Vash Aug 01 '13 at 13:46
@JonSkeet. OOPs. Fixed. Thanks :) – Rohit Jain Aug 01 '13 at 13:47
1

@Vash: Well we don't know what the OP wants for `something2`, which is hardly Rohit's fault... – Jon Skeet Aug 01 '13 at 13:47
1

@Vash. Well, that part is not relevant at all. OP is intrested in how to pass `.class` as argument. I guess he be knowing what type to give for 2nd parameter. And `Object` is not always a good guess. – Rohit Jain Aug 01 '13 at 13:50
@Vash: There is *no* evidence of that at all. All we know about the argument is "something else", which could be anything. Basically, it's irrelevant to the question, as far as I can see. – Jon Skeet Aug 01 '13 at 13:51
this type crashes the application – Lena Bru Aug 01 '13 at 13:59
@LenaBru. Which Java version are you using? And what do you mean by crashes. Please elaborate. Do you get some exception? error? – Rohit Jain Aug 01 '13 at 14:00
Do you get any exception or error? How are you using that parameter? – Rohit Jain Aug 01 '13 at 14:11
this is the answer i was looking for: http://stackoverflow.com/a/5370998/2136812 thanks all for helping out! – Lena Bru Aug 01 '13 at 14:50
@LenaBru. Ah! Good that you found a solution. I haven't used GSon. So, no idea about that. :) – Rohit Jain Aug 01 '13 at 14:55

score 2 · Accepted Answer · answered Aug 01 '13 at 13:55

2

Do you mean something like this:

  public <T> void MyFunction(Class<T> something1, SomeOtherType  something2){
  // T= type parameter inside method
  }

answered Aug 01 '13 at 13:55

Shamim Ahmmed

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Are you sure? T could be treated as a Type inside the method. Please see java Generic – Shamim Ahmmed Aug 01 '13 at 14:01
thank you! I was missing "" declaration in my method, that's why it didn't work – Lena Bru Aug 01 '13 at 14:51
2

Should I deserve +1 from you guys! :) – Shamim Ahmmed Aug 01 '13 at 15:21

writing a function that needs Class.class as a parameter in java

2 Answers2