When finalFinal variables containcan referencesbe used to otherconstruct trees of immutable objects. Once constructed, these objects are typicallyguaranteed requirednot to bechange anymore. To achieve this, an immutable class must only have final fields, tooand these final fields may only have immutable types themselves. Java's primitive types are immutable, as are strings and several other classes.
If thisthe above construction is notviolated by having an object in the casetree that is not immutable, the expectation does not hold that anything reachable via the final variable is constant. For example, the following code defines a coordinate system whose origin should always be at (0, 0). The origin is implemented using a <code>java.awt.Point</code> though, and this class defines its fields as public and modifiable. This means that even when reaching the <code>origin</code> object over an access path with only final variables, that object can still be modified, as the below example code demonstrates.
