Java Reference Material | Java Access Qualifiers

Java Access Qualifiers

Java Access Qualifiers, in Least-Restrictive to Most-Restrictive Order
Access Type	Accessible from same class?	Accessible from any class in same package?	Accessible from any subclass anywhere?	Accessible from any class anywhere?
`public`	yes	yes	yes	yes
`protected`	yes	yes	yes	no
package (default)	yes	yes	no	no
`private`	yes	no	no	no

Access Rules Just Related to Inheritance
Access Type	Accessible from any subclass in same package?	Accessible from any subclass anywhere?
`public`	yes	yes
`protected`	yes	yes
package (default)	yes	no
`private`	no	no

The following character-based diagrams,showing the access qualifier information in pictorial form, are based on those in "On to Java" by Patrick Winston:

public

*------------------------------------------------------------*
| Everywhere else                                            |
*------------------------ | ---------------------------------*
                          |
                          |
                          |
*------------------------ | ---------------------------------*
| *---------------------- | -------*   *-------------------* |
| |                *----- v -----* |   |                   | |
| |                |    Same     | |   |                   | |
| |                |    class    | |   |                   | |
| |                |      |      | |   |                   | |
| | Rest of the    |      v      | |   | Other compilation | |
| | compilation -----> public  <-------- unit, same package| |
| | unit           |      ^      | |   |                   | |
| |                |      |      | |   |                   | |
| |                *----- | -----* |   |                   | |
| *---------------------- | -------*   *-------------------* |
*------------------------ | ---------------------------------*
                          |
                          |
                          |
*------------------------ | ---------------------------------*
| *---------------------- | -------------------------------* |
| |          *----------- | -------*                       | |
| |          | Subclass in another |                       | |
| |          | compilation unit in |                       | |
| |          | another package     |                       | |
| |          *---------------------*                       | |
| *--------------------------------------------------------* |
*------------------------------------------------------------*


protected

*------------------------------------------------------------*
| Everywhere else                                            |
*------------------------ | ---------------------------------*
                          |
                          |
                          | ^
                          *-*
*------------------------------------------------------------*
| *--------------------------------*   *-------------------* |
| |                *-------------* |   |                   | |
| |                |    Same     | |   |                   | |
| |                |    class    | |   |                   | |
| |                |      |      | |   |                   | |
| | Rest of the    |      v      | |   | Other compilation | |
| | compilation ----> protected <------- unit, same package| |
| | unit           |      ^      | |   |                   | |
| |                |      |      | |   |                   | |
| |                *----- | -----* |   |                   | |
| *---------------------- | -------*   *-------------------* |
*------------------------ | ---------------------------------*
                          |
                          |
                          |
*------------------------ | ---------------------------------*
| *---------------------- | -------------------------------* |
| |          *----------- | -------*                       | |
| |          | Subclass in another |                       | |
| |          | compilation unit in |                       | |
| |          | another package     |                       | |
| |          *---------------------*                       | |
| *--------------------------------------------------------* |
*------------------------------------------------------------*


package (default)

*------------------------------------------------------------*
| Everywhere else                                            |
*------------------------ | ---------------------------------*
                          |
                          |
                          | ^
                          *-*
*------------------------------------------------------------*
| *--------------------------------*   *-------------------* |
| |                *-------------* |   |                   | |
| |                |    Same     | |   |                   | |
| |                |    class    | |   |                   | |
| |                |      |      | |   |                   | |
| | Rest of the    |      v      | |   | Other compilation | |
| | compilation -----> default <-------- unit, same package| |
| | unit           |             | |   |                   | |
| |                *-------------* |   |                   | |
| *--------------------------------*   *-------------------* |
*------------------------------------------------------------*
                          *-*
                          | v
                          |
                          |
*------------------------ | ---------------------------------*
| *---------------------- | -------------------------------* |
| |          *----------- | -------*                       | |
| |          | Subclass in another |                       | |
| |          | compilation unit in |                       | |
| |          | another package     |                       | |
| |          *---------------------*                       | |
| *--------------------------------------------------------* |
*------------------------------------------------------------*


private

*------------------------------------------------------------*
| Everywhere else                                            |
*------------------------ | ---------------------------------*
                          | ^
                          *-*
*------------------------------------------------------------*
| *--------------------------------*   *-------------------* |
| |                *-------------* |   |                   | |
| |                |    Same     | |   |                   | |
| |                |    class    | |   |                   | |
| |                |      |      | |   |                   | |
| | Rest of the    |      v      | |   | Other compilation | |
| | compilation --*|   private   | |*--- unit, same package| |
| | unit          ||             | ||  |                   | |
| |             <-*|             | |*->|                   | |
| |                *-------------* |   |                   | |
| *--------------------------------*   *-------------------* |
*------------------------------------------------------------*
                          *-*
                          | v
*------------------------ | ---------------------------------*
| *---------------------- | -------------------------------* |
| |          *----------- | -------*                       | |
| |          | Subclass in another |                       | |
| |          | compilation unit in |                       | |
| |          | another package     |                       | |
| |          *---------------------*                       | |
| *--------------------------------------------------------* |
*------------------------------------------------------------*

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