Sorting Element of list using Comparable interface

  Here is an Example to sort list of added objects to an array list using Comparable  interface.
  import java.util.ArrayList;
    import java.util.Collections;

    public class Sort1 implements Comparable<Object>
    {
    int age;
    String name;
    Sort1(int age,String name)
    {
        this.age=age;
        this.name=name;
    }
    public String toString()
    {
        return "age:" +age+" "+ "name:" +name;
    }
    public int compareTo(Object o)
    {
        return ((Sort1)o).age-age;
    }
    public static void main(String[] args)
    {
        ArrayList<Sort1> list=new ArrayList<Sort1>();
        list.add(new Sort1(60,"byz"));
        list.add(new Sort1(10,"xbc"));
        list.add(new Sort1(20,"ahaitu"));
        Collections.sort(list);
        System.out.println(list);
      
      
    }
    }

Comparing Objects Added to list

Hi Friends



Here we are comparing added objects to list using  Comparator Interface.For this First declare the Employee class as shown below:



import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class Employee1 {
    private int id;
    private String name;
    private int age;
 
    public Employee1(int id,String name,int age) {
        //super();
        this.age = age;
        this.id = id;
        this.name = name;
    }
    public int getId() {
        return id;
    }
    /*public void setId(int id) {
        this.id = id;
    }*/
    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;
    }*/
    @Override
    public String toString() {
        // TODO Auto-generated method stub
        return id+" "+name+" "+age;
    }
    public static void main(String[] args) {
        // TODO Auto-generated method stub
List<Employee1> li=new ArrayList<Employee1>();
Employee1 e=new Employee1(9,"chaitu",26);
Employee1 e1=new Employee1(2,"mahesh",22);
Employee1 e2=new Employee1(8,"vinay",28);
Employee1 e3=new Employee1(6,"ravi",16);
li.add(e);
li.add(e1);
li.add(e2);
li.add(e3);
Collections.sort(li, new MyComparator1());
System.out.println(li);

    }
 
}

Then write the MyComparator1 Class  as shown below

import java.util.Comparator;


public class MyComparator1 implements Comparator<Employee1> {

    @Override
    public int compare(Employee1 o1, Employee1 o2) {
        // TODO Auto-generated method stub
        if(o1.getAge()>o2.getAge())
        return -1;
        else if(o1.getAge()<o2.getAge())
         
            return 1;
        else
        return 0;
        /*if(o1.getId()>o2.getId())
            return 1;
            else if(o1.getId()<o2.getId())
                return -1;
            else
            return 0;*/
    }

}

Now see this results your requirement.

Here it return results based on age in ascending order.

Singleton Example in java

public class Singleton {

    /**
     * @param args
     */
    private  static Singleton instance;
    private Singleton()
    {
       
    }
    public static Singleton createInstance()
    {
        if(instance==null)
        {
            instance=new Singleton();
        }
        return instance;
    }
    public static void main(String[] args) {
       
// TODO Auto-generated method stub
Singleton s1=Singleton.createInstance();
Singleton s2=Singleton.createInstance();
Singleton s3=Singleton.createInstance();
System.out.println(s1+ " "+s2+" "+s3);
    }

}