Spring framework provides the facility to inject collection values via constructor or setter method. We can use the following inside the constructor or property element.
1. List.
2. Set.
3. Map.
Syntax (constructor based dependency injection):
value1 value2 value3
Syntax (setter based dependency injection):
value1 value2 value3
Example Explanation:
We have created two beans “Student” and “Address”. Student class requires an Address class object. In spring configuration file we define Address bean objects and pass these objects as a list in constructor-arg.
Example:
Student.java
package com.w3schools360.business;
import java.util.List;
/**
* This class will be used as a bean class.
* @author W3schools360
*/
public class Student {
private String name;
private String rollNo;
private String className;
private List address;
public Student(List address){
this.address = (List) address;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getRollNo() {
return rollNo;
}
public void setRollNo(String rollNo) {
this.rollNo = rollNo;
}
public String getClassName() {
return className;
}
public void setClassName(String className) {
this.className = className;
}
public List getAddress() {
return address;
}
}
Address.java
package com.w3schools360.business;
/**
* This class will be used as a bean class.
* @author W3schools360
*/
public class Address {
private String addLine;
private String city;
private String state;
private String country;
public String getAddLine() {
return addLine;
}
public void setAddLine(String addLine) {
this.addLine = addLine;
}
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
public String getState() {
return state;
}
public void setState(String state) {
this.state = state;
}
public String getCountry() {
return country;
}
public void setCountry(String country) {
this.country = country;
}
}
applicationContext.java
Test.java
package com.w3schools360.business;
import java.util.List;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Test {
public static void main(String[] args) {
//Get ApplicationContext using spring configuration file.
ApplicationContext context =
new ClassPathXmlApplicationContext("applicationContext.xml");
//Get Student bean object from ApplicationContext instance.
Student student = (Student) context.getBean("student");
//Process Student Object.
System.out.println("Student info: ");
System.out.println("Name: " + student.getName());
System.out.println("RollNo: " + student.getRollNo());
System.out.println("Class: " + student.getClassName());
//Get Address from Student Object.
List studentAddressList = student.getAddress();
//Declare program counter.
int addressCounter = 1;
//Iterate Address List.
for (Address studentAddress : studentAddressList) {
//Process Address Object.
System.out.println("Student Address " +addressCounter+ ": ");
System.out.println("Address Line: "+studentAddress.getAddLine());
System.out.println("City: " + studentAddress.getCity());
System.out.println("State: " + studentAddress.getState());
System.out.println("Country: " + studentAddress.getCountry());
addressCounter++;
}
}
}
Output:
Student info: Name: Jai RollNo: MCA/07/06 Class: MCA Student Address 1: Address Line: Test address1 City: Gurgaon State: Haryana Country: India Student Address 2: Address Line: Test address2 City: Panipat State: Haryana Country: India
