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How to use collections with spring expression language?


This page shows how to use collection objects along with spring expression language. Below example shows how to use list and map objects with spring expression language.

package com.java2novice.beans;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("myCompanyBean")
public class MyCompany {

	private List<Employee> empList;
	private Map<String, Integer> empIdMap;
	
	@Value("#{myCompanyBean.empList[0]}")
	private Employee firstEmployee;
	
	@Value("#{myCompanyBean.empIdMap['Nataraja Gootooru']}")
	private int starEmpId;
	
	public MyCompany(){
		//populate list
		empList = new ArrayList<Employee>();
		empList.add(new Employee(1016, "Nataraja Gootooru"));
		empList.add(new Employee(1015, "Nagesh Yenamala"));
		empList.add(new Employee(1017, "Nikesh Penumalli"));
		//populate map
		empIdMap = new HashMap<String, Integer>();
		empIdMap.put("Nataraja Gootooru", 1016);
		empIdMap.put("Nagesh Yenamala", 1015);
		empIdMap.put("Nikesh Penumalli", 1017);
	}

	public void printEmpInfo(){
		System.out.println(this.firstEmployee.toString());
		System.out.println("Star employee id: "+this.starEmpId);
	}
	
	public List<Employee> getEmpList() {
		return empList;
	}

	public void setEmpList(List<Employee> empList) {
		this.empList = empList;
	}

	public Map<String, Integer> getEmpIdMap() {
		return empIdMap;
	}

	public void setEmpIdMap(Map<String, Integer> empIdMap) {
		this.empIdMap = empIdMap;
	}

	public Employee getFirstEmployee() {
		return firstEmployee;
	}

	public void setFirstEmployee(Employee firstEmployee) {
		this.firstEmployee = firstEmployee;
	}

	public int getStarEmpId() {
		return starEmpId;
	}

	public void setStarEmpId(int starEmpId) {
		this.starEmpId = starEmpId;
	}
}

package com.java2novice.beans;

public class Employee {

	private int empId;
	private String name;
	
	public Employee(int id, String name){
		this.empId = id;
		this.name = name;
	}
	
	public int getEmpId() {
		return empId;
	}
	public void setEmpId(int empId) {
		this.empId = empId;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}

	@Override
	public String toString(){
		return this.empId+" | "+this.name;
	}
	
}

Here is the xml based configuration, you must enable component scan.

<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:context="http://www.springframework.org/schema/context"
	xsi:schemaLocation="http://www.springframework.org/schema/beans
	http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
	http://www.springframework.org/schema/context
	http://www.springframework.org/schema/context/spring-context-3.0.xsd">

    <context:component-scan base-package="com.java2novice.beans" />
</beans>

Spring bean demo class:

package com.java2novice.test;

import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.java2novice.beans.MyCompany;

public class SpringDemo {

	public static void main(String a[]){
		String confFile = "applicationContext.xml";
		ConfigurableApplicationContext context 
							= new ClassPathXmlApplicationContext(confFile);
		MyCompany myCompany = (MyCompany) context.getBean("myCompanyBean");
		myCompany.printEmpInfo();
	}
}

Output:
1016 | Nataraja Gootooru
Star employee id: 1016
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Knowledge Centre
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Object oriented programming organizes a program around its data, i.e. , objects and a set of well defined interfaces to that data. An object-oriented program can be characterized as data controlling access to code.
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About Author

I'm Nataraja Gootooru, programmer by profession and passionate about technologies. All examples given here are as simple as possible to help beginners. The source code is compiled and tested in my dev environment.

If you come across any mistakes or bugs, please email me to [email protected].

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