The lexical scope of a declaration determines where the named entity is
a valid identifier. Every declaration is associated with a lexical
level that corresponds to one of the following Java constructs:
The names at this level include all of the non-nested, outer-level class
and interface declarations in files that belong to the same
package as the file that is being compiled. This level also includes non-nested, outer-level
class and interface declarations that are declared public
in other packages.
- .java file
The names at this level include all of the class
and interface declarations in the file, as well as all of the classes
and interfaces that are imported by the file. The names declared
directly in a file are defined from the beginning to the end of
the file. An import statement defines simple
identifiers as synonyms for names that are only fully qualified
with the name of a package. These synonyms for fully qualified names
are defined from the import statement that defines
them to the end of the file.
- Class or interface declaration
The names at this level include the names of methods, variables,
and classes or interfaces
that are declared directly in the class or interface
declaration, as well as names inherited from superclasses or super
interfaces. The names declared in a class or interface are defined
throughout the class or interface.
- Method declaration
The names at this level include the formal parameters
of the method. The formal parameters are defined throughout the
The names at this level include the local variables, local classes,
and statement labels declared in the block. Statement labels are
defined throughout a block, while local variables and classes are defined from
their declaration to the end of the block.
- A nested block or a for statement
The names at this level include local variables declared in the
initialization of the for statement or the local
variables, classes, and statement labels declared in a nested block. Local
variables declared in the initialization of a for
statement are defined from their declaration to the end of the
for statement. Statement labels are defined
throughout a nested block, while local variables and classes are defined from
their declaration to the end of the nested block.
These lexical levels correspond to nested constructs. When
the Java compiler encounters a name in a program, it finds the declaration
for that name by first looking in the lexical level where the name
is encountered. If the compiler does not find the name in that lexical
level, it searches progressively higher lexical levels until it
finds the declaration. If all of the lexical levels are exhausted,
the compiler issues an error message.
If, however, an
identifier is qualified by a class or package name, the compiler
only searches that lexical level for a declaration.
The for Statement