new

    new <class>

Stack

Before	After
...	objectref
	...

Description

new is used to create object instances.

new takes a single parameter, <class>, the name of the class of object you want to create. <class> is resolved into a Java class (see Chapter 7 for a discussion of how classes are resolved). Then new determines the size in bytes of instances of the given class and allocates memory for the new instance from the garbage collected heap. The fields of the instance are set to the initial value 0 (for numeric and boolean fields), or null (for reference fields). Next, a reference to the new object is pushed onto the operand stack.

Note that the new object is initialize uninitialized - before the new object can be used, one of its <init> methods must be called using invokespecial, as shown in the example below.

Example

; This example creates a new StringBuffer object. This is like the Java code:
;
;    StringBuffer x = new StringBuffer();

; 1. use new to create a new object reference
new java/lang/StringBuffer

; 2. dup the object reference and call its constructor
dup
invokespecial java/lang/StringBuffer/<init>()V

; 3. assign object reference on the stack to a local variable
astore_1
; local variable 1 now contains a StringBuffer object,
; ready for use


; the following example shows how to call a non-default
; constructor. It is like the Java code:
;
;    StringBuffer x = new StringBuffer(100);
new java/lang/StringBuffer
dup
bipush 100
invokespecial java/lang/StringBuffer/<init>(I)V
astore_1