Spring SpEL - Elvis Operator


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SpEL expression supports Elvis operator which is a short form of ternary operator.

// Using ternary operator
String result = name != null ? name: "unknown";

// Using Elvis Operator
result = name?:"unknown";

Following example shows the various use cases.

Example

Let's update the project created in Spring SpEL - Create Project chapter. We're adding/updating following files −

  • Employee.java − Employee class.

  • MainApp.java − Main application to run and test.

Here is the content of Employee.java file −

package com.tutorialspoint;

public class Employee {
   private String name;

   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
}

Here is the content of MainApp.java file −

package com.tutorialspoint;

import java.text.ParseException;
import org.springframework.expression.EvaluationContext;
import org.springframework.expression.ExpressionParser;
import org.springframework.expression.spel.standard.SpelExpressionParser;
import org.springframework.expression.spel.support.StandardEvaluationContext;

public class MainApp {
   public static void main(String[] args) throws ParseException {
      ExpressionParser parser = new SpelExpressionParser();
      Employee employee = new Employee();   
      EvaluationContext employeeContext = new StandardEvaluationContext(employee);

      // Evaluates to "unknown"
      String result = parser.parseExpression("name?:'unknown'").getValue(employeeContext, String.class);
      System.out.println(result);

      employee.setName("Mahesh");

      // Evaluates to "Mahesh"
      result = parser.parseExpression("name?:'unknown'").getValue(employeeContext, String.class);
      System.out.println(result);
   }
}

Output

unknown
Mahesh
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