The ModifyCheckingAccountImpl class provides two command constructors.
One of them takes a command target as an argument and implicitly uses the
default target policy to locate the target. The constructor passes a null
target, so that the default target policy traverses its choices and eventually
finds the default target name, LocalTarget.
Identifying a target with CommandTarget
If you use this default implementation, the command determines
the target by looking through an ordered sequence of four options:
- The CommandTarget value
- The CommandTargetName value
- A registered mapping of a target for a specific command
- A defined default target
If the command finds no target, it returns null.
This example uses
the same constructor to set the target explicitly. This example differs from
the example in
Using a command as follows:
- The command target is set to the checking account rather than null. The
default target policy starts to traverse its choices and finds the target
in the first place it looks.
- It does not have to call the setCheckingAccount method to indicate the
account on which the command should operate; the constructor uses the target
variable as both the target and the account.
{
...
CheckingAccount checkingAccount
....
try {
ModifyCheckingAccountCmd cmd =
new ModifyCheckingAccountCmdImpl(checkingAccount, 1000);
cmd.execute();
}
catch (Exception e) {
System.out.println(e.getMessage());
}
...
}