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    <p>The third constructor is a <em>synthetic</em> constructor generated by the compiler, in order to allow access to the private constructor from the outer class. This is because inner classes (and their enclosing classes' access to their private members) only exist for the Java language and not the JVM, so the compiler has to bridge the gap behind the scenes.</p> <p>Reflection will tell you if a member is synthetic:</p> <pre><code>for (Constructor c : aClass.getDeclaredConstructors()) { System.out.println(c + " " + c.isSynthetic()); } </code></pre> <p>This prints:</p> <pre><code>a.TestNested$A(a.TestNested) false private a.TestNested$A(a.TestNested,int) false a.TestNested$A(a.TestNested,int,a.TestNested$1) true </code></pre> <p>See this post for further discussion: <a href="https://stackoverflow.com/q/921025/697449">Eclipse warning about synthetic accessor for private static nested classes in Java?</a></p> <p><strong>EDIT:</strong> interestingly, the eclipse compiler does it differently than javac. When using eclipse, it adds an argument of the type of the inner class itself:</p> <pre><code>a.TestNested$A(a.TestNested) false private a.TestNested$A(a.TestNested,int) false a.TestNested$A(a.TestNested,int,a.TestNested$A) true </code></pre> <p>I tried to trip it up by exposing that constructor ahead of time:</p> <pre><code>class A { A() { } private A(int a) { } A(int a, A another) { } } </code></pre> <p>It dealt with this by simply adding another argument to the synthetic constructor:</p> <pre><code>a.TestNested$A(a.TestNested) false private a.TestNested$A(a.TestNested,int) false a.TestNested$A(a.TestNested,int,a.TestNested$A) false a.TestNested$A(a.TestNested,int,a.TestNested$A,a.TestNested$A) true </code></pre>
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    1. POIssue with constructors of nested class
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    1. USPaul Bellora
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    1. COThank you for your reply! It is clear, that this method is synthetic. All my question is about this fact, that Java produces such method. The questions are: why it needs special InnerClass for this purposes, why it could use existing inner class for this purposes, and where in specification this things are described?
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      1. USAndremoniy
    2. COVery good answer. Compiler add some synthetically created class and uses it. In decompiled code it just write null to that parameter: `new A(123, null)`. In that way compiler is shore that you will not have any methods with that signature. I just don't know why they didn't throw compiler error here. We are calling private method of inner class here!?
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    3. CO@partlov, great! It is really just `null`. Ok! But may be there is some way for invoke this constructor direct from source code, not through reflection?
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