Groovy: Safe Navigation Operator

Safe Navigation Operator (?.) is used to get rid off NullPointerException.

For example, below script defines an Employee class and a function that prints employee details.

HelloWorld.groovy

class Employee{
 String firstName
 String lastName
}

Employee emp = new Employee()
printEmployeeDetails(emp)

void printEmployeeDetails(Employee employee){
 String firstName, lastName
 
 if(employee.firstName == null){
  firstName = null
 }else{
  firstName = employee.firstName
 }
 
 if(employee.lastName == null){
  lastName = null
 }else{
  lastName = employee.lastName
 }
 
 println "[${firstName}, ${lastName}]"
}

Output

[null, null]

if(employee.firstName == null){

         firstName = null

}else{

         firstName = employee.firstName

}

We can rewrite the above snippet using elvis opeator like below. If firstName of the employee is null, then elvis operator return null, else it return the actual value.

        

String firstName = employee?.firstName

Find the below working application.

HelloWorld.groovy

class Employee{
 String firstName
 String lastName
}

Employee emp = new Employee()
printEmployeeDetails(emp)

void printEmployeeDetails(Employee employee){

 String firstName = employee?.firstName
 String lastName = employee ?.lastName
 
 println "[${firstName}, ${lastName}]"
}

Output

[null, null]

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