Curly brackets are used to indicate scope in Apex (and other C-like languages). It could be the scope of your class, method, or a separate scope that you've defined within one of those.
You can access variables that have been declared in your current scope and parent scope(s), but not those defined in child scopes or parallel scopes.
In addition to this you cannot access instance variables from a static scope without an object reference.
In your case you are trying to access a variable a that has been defined in a parallel scope (the createAcct method) to your current scope (the createContact method).
This can be resolved be passing a reference to your Account object to you createContact method:
private static Contact createContact(Account a)
{
Contact c = new Contact
(
FirstName = 'Jane',
LastName = 'Smith',
Account = a.ID
);
insert c;
return c;
}
Scope Examples
Instance Variables
public class Examples
{ // Begin class scope
Integer classVariable;
private void instanceMethod()
{ // Begin method scope
Integer methodVariable;
// We can access classVariable because it is defined in a parent scope
classVariable = 0; // OK!
// We can access methodVariable because it's defined in the current scope
methodVariable = 0; // OK!
{ // Begin method inner scope
Integer methodInnerVariable;
// We can access classVariable because it is defined in a parent scope
classVariable = 0; // OK!
// We can access methodVariable because it's defined in a parent scope
methodVariable = 0; // OK!
// We can access methodInnerVariable because it's defined in the current scope
methodInnerVariable = 0; // OK!
} // End method inner scope
// We cannot access methodInnerVariable here because it is in a child scope
methodInnerVariable = 0; // ERROR!
if(true)
{ // Begin 'if' scope
Integer methodIfVariable;
} // End 'if' scope
// We cannot access methodIfVariable here because it is in a child scope
methodIfVariable = 0; // ERROR!
} // End method scope
} // End class scope
Static Variables
public class StaticExamples
{ // Begin class scope
static Integer staticClassVariable;
private static void staticMethod()
{ // Begin method scope
Integer staticMethodVariable;
// We can access classVariable because it is defined in a parent scope
staticClassVariable = 0; // OK!
// We can access methodVariable because it's defined in the current scope
staticMethodVariable = 0; // OK!
{ // Begin method inner scope
Integer staticMethodInnerVariable;
// We can access classVariable because it is defined in a parent scope
staticClassVariable = 0; // OK!
// We can access methodVariable because it's defined in a parent scope
staticMethodVariable = 0; // OK!
// We can access methodInnerVariable because it's defined in the current scope
staticMethodInnerVariable = 0; // OK!
} // End method inner scope
// We cannot access methodInnerVariable here because it is in a child scope
staticMethodInnerVariable = 0; // ERROR!
if(true)
{ // Begin 'if' scope
Integer staticMethodIfVariable;
} // End 'if' scope
// We cannot access methodIfVariable here because it is in a child scope
staticMethodIfVariable = 0; // ERROR!
} // End method scope
} // End class scope
Parallel Scopes
public class ParallelExamples
{ // Begin class scope
private void instanceMethod1()
{ // Begin method1 scope
Integer method1Variable;
// We can access method1Variable because it's defined in the current scope
method1Variable = 0; // OK!
} // End method1 scope
private void instanceMethod2()
{ // Begin method2 scope
Integer method2Variable;
// We can access method2Variable because it's defined in the current scope
method2Variable = 0; // OK!
// We cannot access method1Variable because it's defined in a parallel scope
method1Variable = 0; // ERROR!
} // End method2 scope
private void instanceMethod()
{ // Begin method scope
{ // Begin inner scope 1
Integer innerScope1Variable;
// We can access innerScope1Variable because it's defined in the current scope
innerScope1Variable = 0; // OK!
} // End inner scope 1
{ // Begin inner scope 2
// We cannot access innerScope1Variable because it's defined in a parallel scope
innerScope1Variable = 0; // ERROR!
} // End inner scope 2
} // End method scope
} // End class scope
Mixing Instance & Static Variables
public class MixedExamples
{
Integer instanceClassVariable;
static Integer staticClassVariable;
private void AnInstanceMethod()
{ // Begin instance method scope
// We can access instanceClassVariable because it's defined in a parent scope
instanceClassVariable = 0; // OK!
// We can access staticClassVariable because it's defined in a parent scope
staticClassVariable = 0; // OK!
} // End instance method scope
private static void staticMethod(MixedExamples examples)
{ // Begin static method scope
// We cannot access instanceClassVariable because it's an instance variable and we are in a static scope
instanceClassVariable = 0; // ERROR!
// We can however access it if we have an object reference (passed into the function)
examples.instanceClassVariable = 0; // OK!
// We can access staticClassVariable because it's defined in a parent scope
staticClassVariable = 0; // OK!
} // End static method scope
}
