The Java Language Specification, Third Edition

EXPRESSIONS Runtime Evaluation of Method Invocation 15.12.4
15.12.4.6 Example: Target Reference and Static Methods
When a target reference is computed and then discarded because the invocation
mode is static, the reference is not examined to see whether it is null:
class Test {
static void mountain() {
System.out.println("Monadnock");
}
static Test favorite(){
System.out.print("Mount ");
return null;
}
public static void main(String[] args) {
favorite().mountain();
}
}
which prints:
Mount Monadnock
Here favorite returns null, yet no NullPointerException is thrown.
15.12.4.7 Example: Evaluation Order
As part of an instance method invocation (§15.12), there is an expression that
denotes the object to be invoked. This expression appears to be fully evaluated
before any part of any argument expression to the method invocation is evaluated.
So, for example, in:
class Test {
public static void main(String[] args) {
String s = "one";
if (s.startsWith(s = "two"))
System.out.println("oops");
}
}
the occurrence of s before “.startsWith” is evaluated first, before the argument
expression s="two". Therefore, a reference to the string "one" is remembered as
the target reference before the local variable s is changed to refer to the string
"two". As a result, the startsWith method is invoked for target object "one"
with argument "two", so the result of the invocation is false, as the string "one"
does not start with "two". It follows that the test program does not print “oops”.
DRAFT
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