java - Why aren't fields initialized to non-default values when a method is run from super()? -

i must have spent on hour trying figure out reason unexpected behavior. ended realizing field wasn't being set i'd expect. before shrugging , moving on, i'd understand why works this.

in running example below, i'd expect output true, it's false. other tests show whatever type default value is.

public class classone {      public classone(){         firemethod();     }      protected void firemethod(){     }  }  public class classtwo extends classone {      boolean bool = true;      public classtwo() {         super();     }      @override     protected void firemethod(){         system.out.println("bool="+bool);     }      public static void main(string[] args) {         new classtwo();     } } 

output:

bool=false 

boolean bool = true;  public classtwo() {     super(); } 

is identical to

boolean bool;  public classtwo() {     super();     bool = true; } 

the compiler automatically moves fields initializations within constructor (just after super constructor call, implicitly or explicitly).

since boolean field default value false, when super() called (and classone() , firemethod()), bool hasn't been set true yet.

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fun fact: following constructor

public classtwo() {     super();     firemethod(); } 

will understood as

public classtwo() {     super();     bool = true;     firemethod(); } 

by jvm, , output be

bool=false bool=true