gson and references

Question

I've a small app in Android which have to comunicate with a server through a socket. The question is: can I use Gson to serialize the references of the object? I make an example: if I have a B class like this: ``` public class B{ int n; public B(int n){ this.n=n; } public int getN() { return n; } public void setN(int n) { this.n = n; } public B() { super(); } } ``` and an A class like this ``` public class A{ B b1; B b2; B b3; public B getB1() { return b1; } public void setB1(B b1) { this.b1 = b1; } public B getB2() { return b2; } public void setB2(B b2) { this.b2 = b2; } public B getB3() { return b3; } public void setB3(B b3) { this.b3 = b3; } public A(B b1, B b2, B b3) { super(); this.b1 = b1; this.b2 = b2; this.b3 = b3; } public A() { super(); } } ``` and than I call ``` B b1 = new B(1); B b2 = new B(2) A a = new A(b1,b1,b2); ``` if I serialize (with `(new Gson()).toJson(a,A.class)` the a object I obtain `{"b1":{"n":1},"b2":{"n":1},"b3":{"n":2}}` but I'd prefer have something link…

Accepted Answer

Take a look at GraphAdapterBuilder, which can do this. You'll need to copy that file into your application because it isn't included in Gson.

```
Roshambo rock = new Roshambo("ROCK");
Roshambo scissors = new Roshambo("SCISSORS");
Roshambo paper = new Roshambo("PAPER");
rock.beats = scissors;
scissors.beats = paper;
paper.beats = rock;

GsonBuilder gsonBuilder = new GsonBuilder();
new GraphAdapterBuilder()
    .addType(Roshambo.class)
    .registerOn(gsonBuilder);
Gson gson = gsonBuilder.create();

assertEquals("{'0x1':{'name':'ROCK','beats':'0x2'}," +
    "'0x2':{'name':'SCISSORS','beats':'0x3'}," +
    "'0x3':{'name':'PAPER','beats':'0x1'}}",
    gson.toJson(rock).replace('\"', '\''));
```

https://code.google.com/p/google-gson/source/browse/trunk/extras/src/main/java/com/google/gson/graph/GraphAdapterBuilder.java

gson and references

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