Initialize field before super constructor runs?

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No, there is no way to do this.

According to the language specs, instance variables aren’t even initialized until a super() call has been made.

These are the steps performed during the constructor step of class instance creation, taken from the link:

  1. Assign the arguments for the constructor to newly created parameter
    variables for this constructor invocation.
  2. If this constructor begins with an explicit constructor invocation
    (§8.8.7.1) of another constructor in the same class (using this),
    then evaluate the arguments and process that constructor invocation
    recursively using these same five steps. If that constructor
    invocation completes abruptly, then this procedure completes
    abruptly for the same reason; otherwise, continue with step 5.
  3. This constructor does not begin with an explicit constructor
    invocation of another constructor in the same class (using this). If
    this constructor is for a class other than Object, then this
    constructor will begin with an explicit or implicit invocation of a
    superclass constructor (using super). Evaluate the arguments and
    process that superclass constructor invocation recursively using
    these same five steps. If that constructor invocation completes
    abruptly, then this procedure completes abruptly for the same
    reason. Otherwise, continue with step 4.
  4. Execute the instance initializers and instance variable initializers
    for this class, assigning the values of instance variable
    initializers to the corresponding instance variables, in the
    left-to-right order in which they appear textually in the source
    code for the class. If execution of any of these initializers
    results in an exception, then no further initializers are processed
    and this procedure completes abruptly with that same exception.
    Otherwise, continue with step 5.
  5. Execute the rest of the body of this constructor. If that execution
    completes abruptly, then this procedure completes abruptly for the
    same reason. Otherwise, this procedure completes normally.

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