Java Optional overhead

JavaOptionalOverhead.java

// Java
// Optional Type Overhead
Optional<String> strOpt = null; // Compile OK

Optional<String> strOpt = Optional.empty(); // Compile OK

strOpt = null; // Compile OK

strOpt == null; // Compile OK => true

strOpt = Optional.of("gary"); // Compile OK

strOpt = Optional.ofNullable("gary"); // Compile OK

// cannot direct assign a value
strOpt = "gary"; // Compile error: Type mismatch
  
// cannot direct compare with a value
strOpt.equal("gary"); // Compile error: Type mismatch
  
strOpt.equal(Optional.of("gary")); // Compile OK, true
  

// unwrap and compare the wrapped value
if(strOpt.isPresent()){
  final String str = strOpt.get();
  return str.equal("gary");
} 
else {
  return false
}

// do something when the wrapped value is not null
strOpt.ifPresent(str -> {
  doSth(str)
});
  
// Easy to be mis-used
// in some case,
// null is a good representation of nothing instead of empty String
String str = strOpt.orElse("");

// throw NullPointerException if the wrapped value is null
String str = strOpt.get();