Adapter Pattern

• aka Wrapper
• Convert the interface of a class into another interface the clients expect
• Java Examples:
  • Stream classes
    • InputStreamReader converts InputStream to Reader interface
  • Arrays.asList()
    • Convert (Wraps) array to List interface
    • ArrayList class behaves as adapter of array to List interface
    • The adapter class implements output type interface and behaves like the interface

Implementation

interface Student {
	public String getName();
	public String getSurName();
}
 
class CollegeStudent implements Student {
	private String name;
	private String surName;
	@Override
	public String getName() { return this.name; }
	@Override
	public String getSurName() { return this.surName; }
}
 
class SchoolStudent {
	private String firstName;
	private String lastName;
	public String getFirstName() { return this.firstName; }
	public String getLastName() { return this.lastName; }
}
 
// Create an Adapter of type Student
class SchoolStudentAdapter implements Student {
	private SchoolStudent schoolStudent;
	public SchoolStudentAdapter(SchoolStudent student) {
		this.schoolStudent = schoolStudent;
	}
	@Override
	public String getName() { return this.schoolStudent.getFirstName(); }
	@Override
	public String getSurName() { return this.schoolStudent.getLastName(); }
}

• Driver

public class Demo {
    public static void main(String[] args) {
	    SchoolStudent schoolStudent = new SchoolStudent("Rohan", "Roy");
	    // convert "SchoolStudent" to "Student" type
        Student s = new SchoolAdapter(schoolStudent)
    }
}