new

Operation

Create new object

Format

new
indexbyte1
indexbyte2

Forms

new = 187 (0xbb)

Operand Stack

... ..., objectref

Description

The unsigned indexbyte1 and indexbyte2 are used to construct an index into the runtime constant pool of the current class (§3.6), where the value of the index is (indexbyte1 << 8) | indexbyte2. The runtime constant pool item at the index must be a symbolic reference to a class, array, or interface type. The named class, array, or interface type is resolved (§5.4.3.1) and should result in a class type (it should not result in an array or interface type). Memory for a new instance of that class is allocated from the garbage-collected heap, and the instance variables of the new object are initialized to their default initial values (§2.5.1). The objectref, a reference to the instance, is pushed onto the operand stack.

On successful resolution of the class, it is initialized (§5.5) if it has not already been initialized.

Linking Exceptions

During resolution of the symbolic reference to the class, array, or interface type, any of the exceptions documented in Section 5.4.3.1 can be thrown.

Otherwise, if the symbolic reference to the class, array, or interface type resolves to an interface or is an abstract class, new throws an InstantiationError.

Runtime Exception

Otherwise, if execution of this new instruction causes initialization of the referenced class, new may throw an Error as detailed in Section 2.17.5.

Note

The new instruction does not completely create a new instance; instance creation is not completed until an instance initialization method has been invoked on the uninitialized instance.

newarray

Operation

Create new array

Format

newarray
atype

Forms

newarray = 188 (0xbc)

Operand Stack

..., count ..., arrayref

Description

The count must be of type int. It is popped off the operand stack. The count represents the number of elements in the array to be created.

The atype is a code that indicates the type of array to create. It must take one of the following values:

Array Type	atype
T_BOOLEAN	4
T_CHAR	5
T_FLOAT	6
T_DOUBLE	7
T_BYTE	8
T_SHORT	9
T_INT	10
T_LONG	11

A new array whose components are of type atype and of length count is allocated from the garbage-collected heap. A reference arrayref to this new array object is pushed into the operand stack. Each of the elements of the new array is initialized to the default initial value for the type of the array (§2.5.1).

Runtime Exception

If count is less than zero, newarray throws a NegativeArraySizeException.

Notes

In Sun's implementation of the Java virtual machine, arrays of type boolean (atype is T_BOOLEAN) are stored as arrays of 8-bit values and are manipulated using the baload and bastore instructions, instructions that also access arrays of type byte. Other implementations may implement packed boolean arrays; the baload and bastore instructions must still be used to access those arrays.

nop

Operation

Do nothing

Format

nop

Forms

nop = 0 (0x0)

Operand Stack

No change

Description

Do nothing.

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The Java^TM Virtual Machine Specification
Copyright © 1999 Sun Microsystems, Inc. All rights reserved
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