1Z0-808: Java SE 8 Programmer IDemo

m1() is public, so it is accessible through a Tree reference. m2() is private, and m4() has package-private access, so neither is accessible from Plant in the different branch package. m3() is protected, but outside Tree’s package a subclass may access it only through a reference whose type is the subclass or one of its subclasses; t is declared as Tree, so t.m3() is invalid. Oracle’s Java Language Specification §6.6.2.1 defines this protected-access restriction.