Spring SpEL - List

SpEL expression supports accessing list and using their indexes of an list of an object.

• We can access nested lists as well within an SpEL expression.

Following example shows the various use cases.

Example - Usage of lists in SpEL

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

• Employee.java − Employee class.

• Dept.java − Department class.

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

Employee.java

Here is the content of Employee.java file −

package com.tutorialspoint;

import java.util.List;

public class Employee {
   private List<String> awards;
   public List<String> getAwards() {
      return awards;
   }
   public void setAwards(List<String> awards) {
      this.awards = awards;
   }
}

Dept.java

Here is the content of Dept.java file −

package com.tutorialspoint;

import java.util.List;

public class Dept {
   private List<Employee> employees;
   public List<Employee> getEmployees() {
      return employees;
   }
   public void setEmployees(List<Employee> employees) {
      this.employees = employees;
   }
}

MainApp.java

Here is the content of MainApp.java file −

package com.tutorialspoint;

import java.text.ParseException;
import java.util.Arrays;
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();
      employee.setAwards(Arrays.asList("Star of the Month", "Champion", "Accelerator"));

      Dept dept = new Dept();
      dept.setEmployees(Arrays.asList(employee));
      EvaluationContext employeeContext = new StandardEvaluationContext(employee);

      // evaluates to "Accelerator"
      String award = parser.parseExpression("awards.get(2)").getValue(employeeContext, String.class);
      System.out.println(award);

      EvaluationContext deptContext = new StandardEvaluationContext(dept);

      // evaluates to "Champion"
      award = parser.parseExpression("employees.get(0).awards.get(1)").getValue(deptContext, String.class);
      System.out.println(award);
   }
}

Output

Once you are done creating the source and bean configuration files, let us run the application. If everything is fine with your application, it will print the following message −

Accelerator
Champion