iconst_n : push the integer constant 0, 1, 2, 3, 4 or 5 : index :

Description

iconst_n represents the series of opcodes iconst_0, iconst_1, iconst_2, iconst_3, iconst_4 and iconst_5. These are used to push the constant ints 0 through 5 onto the stack. For example, to push the int zero onto the stack, use:

iconst_0 ; push 0 onto the stack.

Note that you could also use:

bipush 0 ; push 0 onto the stack

or

sipush 0 ; push 0 onto the stack

or

ldc 0 ; push 0 onto the stack

although these instructions are typically less efficient than the equivalent iconst_n and also take up more bytes in the class file.

Example

iconst_0  ; push 0 onto the stack
iconst_1  ; push 1 onto the stack
iconst_2  ; push 2 onto the stack
iconst_3  ; push 3 onto the stack
iconst_4  ; push 4 onto the stack
iconst_5  ; push 5 onto the stack

See also

bipush sipush ldc ldc_w ldc2_w aconst_null iconst_m1 lconst_l fconst_f dconst_d

Stack

Before	After
...	<n>
	...

Bytecode

Type	Description
u1	iconst_0 opcode = 0x03 (3)
u1	iconst_1 opcode = 0x04 (4)
u1	iconst_2 opcode = 0x05 (5)
u1	iconst_3 opcode = 0x06 (6)
u1	iconst_4 opcode = 0x07 (7)
u1	iconst_5 opcode = 0x08 (8)