Representation and efficiency of Switch statements in bytecode?

Question

Though a switch statement can be represented as a series of if statements, it appears that when a Java switch statement is compiled into bytecode, a different approach is used.

• What is the representation used by bytecode?
• I assume this alternate representation is for efficiency reasons, so how does the efficiency compare to that of just an if statement representation?
• Are there any other considerations that have led to using this representation?

Answer 1

Read the spec . In Java, if you code a switch statement, then depending on various things the switch is converted into a tableswitch instruction in bytecode. Essentially a jump table. What the bytecode looks like may be irrelavent though, if the JIT can optimize it into something more efficient. This is of course, platform dependent.