baload : retrieve byte/boolean from array : index : visitInsn()

Description

Retrieves a byte from a byte array, expands it to an integer and places it on the operand stack. arrayref is a reference to an array of bytes. index is an int. The arrayref and index are removed from the stack, and the 8-bit signed byte at the given index in the array is retrieved, sign-extended to a 32-bit int, and pushed onto the stack.

baload is also used to retrieve values from boolean arrays. In this case, arrayref is a reference to an array of booleans (see the newarray instruction) . If the entry at the given index is true, then the int 1 is pushed onto the stack, otherwise the int 0 is pushed onto the stack. In Sun's implementation, boolean arrays are actually stored as byte arrays, using one byte per boolean value. Other implementations might use packed arrays - or even int arrays - this is invisible to programs running on the JVM, which always use baload and bastore to access and store values in boolean arrays.

Example

; This is like the Java code:
;     byte x = arr[0];
; where x is local variable 2 and arr is a byte array in local variable 1
aload_1       ; load local variable 1 onto the stack
iconst_0      ; push the integer 0 onto the stack
baload        ; retrieve the entry
istore_2      ; store the entry in local variable 2

Exceptions

NullPointerException - arrayref is null

ArrayIndexOutOfBoundsException - index is < 0 or >= arrayref.length

See also

iaload laload faload daload aaload caload saload iastore lastore fastore dastore aastore bastore castore sastore newarray

Stack

Before	After
index	value
arrayref	...
...	...

Bytecode

Type	Description
u1	baload opcode = 0x33 (51)