why kotlin lambda decompiled to java code is (Function0)null.INSTANCE

Question

when I declare a property in a class as following:

class xx{
    var b:()->Boolean={false}
}

and then decompiled as following:

......

public xxx() {
    this.b = (Function0)null.INSTANCE;
}

......

what does the (Function0)null.INSTANCE stand for? I think it will be :

this.b= new Function0() {
        public final Object invoke() {
                 return false;
         }
};

but it doesn't ,why?

Thanks!

Which decompiler did you use? Can you also post the imports. — guenhter
– guenhter, Commented Jul 3, 2017 at 5:26
AndroidStudio built in:Tools->Kotlin->Show Kotlin Bytecode->Decompile — xzw happy
– xzw happy, Commented Jul 3, 2017 at 9:32

guenhter · Accepted Answer · 2017-07-03 05:50:01Z

6

Decompiler not showing the correct result: e.g. when doing it with JD-GUI, you get:

final class xx$b$1 extends Lambda implements kotlin.jvm.functions.Function0<Boolean> { 
  public final boolean invoke() { return false; }

  public static final 1 INSTANCE = new 1();
  xx$b$1()
  {
    super(0);
  }
}


public final class xx { 
  // ... getter and setter
  private Function0<Boolean> b = (Function0)xx.b.1.INSTANCE;
}

answered Jul 3, 2017 at 5:50

guenhter

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1 Comment

guenhter Over a year ago

Hi @xzwhappy, if this is the solution, please just mark this answer as such. thx

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