1 số giới hạn các lệnh khi hack game[download=green]iconst_x takes a single byte andallows any value from -1 to 5. -1 is iconst_m1.
*. bipush x takes two bytes and allows values from -128 to 127.
*. sipush x takes three bytes and allows values from -32768 to 32767 (-2^15 to 2^15-1).
For integer contants outside this range, you must use the ldc and ldc_w instructions mentioned earlier. The instruction itself only takes 2 bytes (3 for ldc_w), but italso creates an entry in the constant pool, which takes up 5 bytes. All of the following instructions will push -1 to the stack.
*. iconst_m1
*. bipush -1
*. sipush -1
*. ldc -1
*. ldc_w -1[/download]