invokeinterface

Otherwise, if the selected method is abstract, invokeinterface throws an AbstractMethodError.

Otherwise, if the selected method is native and the code that implements the method cannot be loaded or linked, invokeinterface throws an UnsatisfiedLinkError.

Runtime Exception
Otherwise, if objectref is null, the invokeinterface instruction throws a NullPointerException.

Notes
Unlike invokevirtual, invokestatic, and invokespecial, the number of arguments words (nargs) for the method invocation is made available as an operand of the invokeinterface instruction. As with the other instructions, that value can also be derived from the descriptor of the selected method. The derived value must be identical to the value of the nargs operand. This redundancy is historical, but the nargs operand also reserves space in the instruction for an operand used by the invokeinterface_quick pseudo-instruction which may replace invokeinterface at run time. See Chapter 9, "An Optimization," for information on invokeinterface_quick.

The fourth operand byte of the invokeinterface instruction is unused by the instruction itself and must be zero. It exists only to reserve space for an additional operand added if the invokeinterface instruction is replaced by the invokeinterface_quick pseudo-instruction at run time.

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Java Virtual Machine Specification (HTML generated by dkramer on February 25, 1997)
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