JAVA EE: Java : Collection Framework : TreeMap (Add User-Defined Object)

Wednesday 25 February 2015

Java : Collection Framework : TreeMap (Add User-Defined Object)

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Employee.java

public class Employee
{

    private String name;
    private int    age;
    private int    salary;

    public Employee( String name, int age, int salary )
    {
        super();
        this.name = name;
        this.age = age;
        this.salary = salary;
    }

    public String getName()
    {
        return name;
    }

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

    public int getAge()
    {
        return age;
    }

    public void setAge( int age )
    {
        this.age = age;
    }

    public int getSalary()
    {
        return salary;
    }

    public void setSalary( int salary )
    {
        this.salary = salary;
    }

    @Override
    public String toString()
    {
        return "Employee [name=" + name + ", age=" + age + ", salary=" + salary
                + "]";
    }

}

TreeMapExample.java

import java.util.Map;
import java.util.Set;
import java.util.TreeMap;

/*
 * Example of adding User defined Object.
 */
public class TreeMapExample
{
    public static void main( String[] args )
    {

        TreeMap<Integer, Employee> treeMap = new TreeMap<Integer, Employee>();

        Employee john = new Employee("John", 32, 40000);
        Employee david = new Employee("David", 42, 80000);
        Employee peter = new Employee("Peter", 52, 150000);

        /*
         * Key is EmpId - Value is Employee Object
         */
        treeMap.put(20, john);
        treeMap.put(10, david);
        treeMap.put(40, peter);

        System.out.println("treeMap : " + treeMap + "\n");

        Set<Map.Entry<Integer, Employee>> set = treeMap.entrySet();

        System.out.println("set : " + set + "\n");

        System.out.println("-----------------------");
        System.out.println("Key" + " | " + "value");
        System.out.println("-----------------------");

        for( Map.Entry<Integer, Employee> entry : set )
        {
            int empId = entry.getKey();
            Employee employee = entry.getValue();
            System.out.println(empId + "   | " + employee);
        }

    }
}

Output

treeMap : {10=Employee [name=David, age=42, salary=80000], 20=Employee [name=John, age=32, salary=40000], 40=Employee [name=Peter, age=52, salary=150000]}

set : [10=Employee [name=David, age=42, salary=80000], 20=Employee [name=John, age=32, salary=40000], 40=Employee [name=Peter, age=52, salary=150000]]

-----------------------
Key | value
-----------------------
10   | Employee [name=David, age=42, salary=80000]
20   | Employee [name=John, age=32, salary=40000]
40   | Employee [name=Peter, age=52, salary=150000]