Collection Examples in Java

package come;

public abstract class Connection implements Comparable<Connection> {

private int connectionId;
private int customerId;
private double balance;
public Connection(int connectionId,int customerId,double balance)
{
this.connectionId=connectionId;
this.customerId=customerId;
this.balance=balance;
}
abstract double recharge(double bal);
abstract double deduct(double bal);
public int getConnectionId() {
return connectionId;
}
public int getCustomerId() {
return customerId;
}
public double getBalance() {
return balance;
}
public void setBalance(double balance) {
this.balance = balance;
}
public String toString()
{
return connectionId+" "+customerId+" "+balance;
}
public int compareTo(Connection o) {

int code = 0;
if(o.getConnectionId()< connectionId)
{
code = 1;
}
else if(o.getConnectionId()> connectionId)
{
code = -1;
}
return code;
}
}

package come;

import java.util.*;

public class Inventory {

ArrayList<Connection> connections;

Inventory()

{

connections=new ArrayList<Connection>();

}

boolean addConnection(Connection con)

{

boolean exist=true;

for(Connection c:connections)

{

if(c.getConnectionId()==con.getConnectionId())

{

exist=false;

break;

}

}

if(exist==true)

{

connections.add(con);

}

return exist;

}

double recharge(int conId,double recAmount)

{

double total=-1;

for(Connection con:connections)

{

if(con.getConnectionId()==conId)

{

total=con.getBalance();

total=total+recAmount;

//con.recharge(recAmount);

break;

}

}

return total;

}

double deduct(int conId,double dedAmount) throws ConnectionLockedException

{

double total=-1;

for(Connection con:connections)

{

if(con.getConnectionId()==conId)

{

if(con.getBalance()<0)

{

throw new ConnectionLockedException(con.getBalance());

}

else

{

total=con.getBalance();

total=total-dedAmount;

}

}

}

return total;

}

Set<Integer> getUniqueCustomerIDs()

{

Set<Integer> set=new HashSet<Integer>();

for(Connection con:connections)

{

set.add(con.getConnectionId());

}

return set;

}

HashMap<Integer,Connection> getConnectionHashMap()

{

HashMap<Integer,Connection> hMap=new HashMap<Integer,Connection>();

for(Connection con:connections)

{

hMap.put(con.getConnectionId(), con);

}

return hMap;

}

}

package come;

public class ConnectionLockedException extends Exception {

double currentBalance;

ConnectionLockedException(double currentBalance)

{

this.currentBalance=currentBalance;

}

public String getMessage()

{

return currentBalance+" is invalid balance";

}

}

package come;

import java.util.TreeSet;

public class NewInventory {

TreeSet<Connection>  conTree=null;

public NewInventory()

{

conTree=new TreeSet<>();

}

TreeSet<Connection> getConnections()

{

return conTree;

}

int addConnection(Connection con)

{

conTree.add(con);

return conTree.size();

}

}

package com;

public class Hobby {

String hobbyDescription;

String hobbyName;

public String getHobbyDescription() {

return hobbyDescription;

}

public void setHobbyDescription(String hobbyDescription) {

this.hobbyDescription = hobbyDescription;

}

public String getHobbyName() {

return hobbyName;

}

public void setHobbyName(String hobbyName) {

this.hobbyName = hobbyName;

}

public String toString()

{

return hobbyDescription+hobbyName;

}

}

package come;

public class ConnectionDemo {

public static void main(String[] args) {

Inventory inv=new Inventory();

Prepaid con1=new Prepaid(1,1,100);

Prepaid con2=new Prepaid(2,2,-122);

Prepaid con3=new Prepaid(3,3,300);

System.out.println(inv.addConnection(con1));

System.out.println(inv.addConnection(con2));

System.out.println(inv.addConnection(con3));

System.out.println("Recharge "+inv.recharge(1, 122));

try

{

System.out.println("Deduct1 "+inv.deduct(1, 500));

System.out.println("Deduct "+inv.deduct(2, 1220));

}catch(ConnectionLockedException ce)

{

ce.getMessage();

}

System.out.println("Unique Customer IDs "+inv.getUniqueCustomerIDs());

System.out.println("Hash Map "+inv.getConnectionHashMap().toString());

Prepaid con4=new Prepaid(3,3,300);

System.out.println(inv.addConnection(con4));

NewInventory ni=new NewInventory();

System.out.println("Tree "+ni.addConnection(con1));

System.out.println("Tree "+ni.addConnection(con2));

System.out.println("Tree "+ni.addConnection(con3));

System.out.println("Tree "+ni.addConnection(con4));

System.out.println("Tree output "+ni.getConnections());

}

}