check-cast

Purpose

Throw if the reference in the given register cannot be cast to the indicated type. The type must be a reference type (not a primitive type).

Details

Constraints

• A must be a valid register index in the current stack frame.
• Register vA must contain a reference value.
• B must be a valid index into the type pool.
• Type pool entry B must contain a valid type descriptor for a reference type.

Behavior

• An attempt is made to get a reference to the class C the name of which is contained in type pool entry B.
• If C has not been loaded and resolved before, it is being loaded and resolved. All exceptions that are possible during class loading can occur at this point.
• The run-time type of the object reference vA is compared against C.
  • If vA is null, the instruction succeeds (without further effects).
  • If vA is assignment compatible with C according to the usual rules of the Java programming language, the instruction succeeds (without further effects).

Exceptions

• ClassCastException is thrown if vA is either not null or not assignment compatible with C.