A null pointer is a declared variable that is not assigned to any value, or explicitly assigned as null.
Consider the following:
var streetAddress;
The variable has been declared, but it does not reference any value. Like an envelope without an address, the streetAddress variable holds no value. By attempting to access a property or call a function on the null value will cause a null pointer exception.
var streetAddress;
var streetAddressParts;
try {
streetAddressParts = streetAddress.split(" ");
} catch (err) {
qie.info("Told ya, we caught an error: " + err);
}
streetAddress = "459 Dirello Street";
streetAddressParts = streetAddress.split(" "); // no null pointer exception because it has a value
Always check if the variable is null before using any property or function on it. This is a good habit when pulling from the messageCache just in case the cache was not defined (which would then return null).
var streetAddress = messasgeCache.getValue("address1");
var streetAddressParts;
if (streetAddress !== null) {
streetAddressParts = streetAddress.split(" ");
}
Better safe than sorry.
