CODEWITHSUNDEEP
javareflection
bespectacled
bespectacled

Reputation: 2901

Check if class member is a class object

I have a class whose member is another class object among other members. I would like to know how to determine whether the this field is a java class (user defined). That is, I have something like this: The user passes the name of a java class. If the package contains a class by this name, then I get all the declared fields of this class and do a DFS kind of operation on those data members that are class objects. 

class A {
  private String c;
  private B b;
}

class B {
  private int d;
  private String f;
}

So now in A, I only have to select B and visit B's members. How to do this ?

Thanks.

Upvotes: 1

Views: 1707

Answers (3)

zacheusz
zacheusz

Reputation: 8842

There is one more trick. But results strictly depends on a classloader. It may help you checking if a class is custom user class. Try running this code to determine location of jar:

    ProtectionDomain domain = allDeclaredFields[i].getClass().getProtectionDomain();
    System.out.println("domain: " + domain);
    CodeSource codeSource = domain.getCodeSource();
    if(codeSource != null) {
       System.out.println("location: " + codeSource.getLocation());
    } else {
        System.out.println("null location, probably JRE class");
    }

Upvotes: 1

Rasel
Rasel

Reputation: 15477

If i got your qusestion correctly you are trying to find whether a object belongs to a class or not.There is a java operator called instanceof to check it

if(b instanceof B){
//b is an object of B
}

Upvotes: 0

user852502
user852502

Reputation: 89

You'll want to use Java reflection. See http://download.oracle.com/javase/tutorial/reflect/index.html for more information (click on members, should be what you need)

Upvotes: 0

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