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12: Complete the trades matching logic

Q. Given the following code


import java.io.BufferedWriter;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class TradeMatcher {

    private final Scanner in;
    private final BufferedWriter out;

    public TradeMatcher(Scanner in, BufferedWriter out) {
        this.in = in;
        this.out = out;
    }

    /*
     * store state
     */
   
   //********** TO BE COMPLETED *************
   
   
    /**
     * Matching Trade
     * @param trade
     * @return
     */
    public List<Long> match(Trade trade) {
        //********** TO BE COMPLETED *************
         
        return new ArrayList<Long>();
    }

    private void processTrades() throws IOException {
        while (in.hasNext()) {
            Trade order = readTrade();
            List<Long> matchingIds = match(order);
            outputMatches(matchingIds);
        }
        out.close();
    }

    private Trade readTrade() {
        final long tradeId = in.nextLong();
        final String securitySymbol = in.next();
        final Side customerSide = Side.valueOf(in.next());
        final long size = in.nextLong();
        return new Trade(tradeId, securitySymbol, customerSide, size);
    }

    private void outputMatches(List<Long> matchingIds) throws IOException {
        int length = matchingIds.size();
        out.write(matchingIds.size() + " matches found. Matching ids are: [");
        for (int i = 0; i < length; i++) {
            out.write(String.valueOf(matchingIds.get(i)));
            if (i < length - 1) {
                out.write(',');
            }
        }
        out.write("]");
        out.newLine();
    }

    public static void main(String[] args) throws IOException {
        Scanner in = new Scanner(System.in);
        BufferedWriter out = new BufferedWriter(new OutputStreamWriter(System.out));

        TradeMatcher m = new TradeMatcher(in, out);
        m.processTrades();
    }

    //inner class
    private static class Trade {
        final long tradeId;  // Unique id
        final String securitySymbol; //if symbol matches & side differs then trade matches
        final Side side; //BUY or SELL
        long size;  //trade QTY

        public Trade(long orderId, String securitySymbol, Side customerSide, long size) {
            this.tradeId = orderId;
            this.securitySymbol = securitySymbol;
            this.side = customerSide;
            this.size = size;
        }
    }

    private enum Side {
        BUY, SELL
    }
}

import java.io.BufferedWriter;

import java.io.IOException;

import java.io.OutputStreamWriter;

import java.util.ArrayList;

import java.util.List;

import java.util.Scanner;

public class TradeMatcher {

private final Scanner in;

private final BufferedWriter out;

public TradeMatcher(Scanner in, BufferedWriter out) {

this.in = in;

this.out = out;

}

* store state

//********** TO BE COMPLETED *************

/**

* Matching Trade

* @param trade

* @return

public List<Long> match(Trade trade) {

//********** TO BE COMPLETED *************

return new ArrayList<Long>();

}

private void processTrades() throws IOException {

while (in.hasNext()) {

Trade order = readTrade();

List<Long> matchingIds = match(order);

outputMatches(matchingIds);

}

out.close();

}

private Trade readTrade() {

final long tradeId = in.nextLong();

final String securitySymbol = in.next();

final Side customerSide = Side.valueOf(in.next());

final long size = in.nextLong();

return new Trade(tradeId, securitySymbol, customerSide, size);

}

private void outputMatches(List<Long> matchingIds) throws IOException {

int length = matchingIds.size();

out.write(matchingIds.size() + " matches found. Matching ids are: [");

for (int i = 0; i < length; i++) {

out.write(String.valueOf(matchingIds.get(i)));

if (i < length - 1) {

out.write(',');

}

out.write("]");

out.newLine();

}

public static void main(String[] args) throws IOException {

Scanner in = new Scanner(System.in);

BufferedWriter out = new BufferedWriter(new OutputStreamWriter(System.out));

TradeMatcher m = new TradeMatcher(in, out);

m.processTrades();

}

//inner class

private static class Trade {

final long tradeId; // Unique id

final String securitySymbol; //if symbol matches & side differs then trade matches

final Side side; //BUY or SELL

long size; //trade QTY

public Trade(long orderId, String securitySymbol, Side customerSide, long size) {

this.tradeId = orderId;

this.securitySymbol = securitySymbol;

this.side = customerSide;

this.size = size;

}

private enum Side {

BUY, SELL

}

Fill in required code in the “//********** TO BE COMPLETED *************” section within the “match(Trade trade)” method and in the variables declaration section at the top. Assume that this object is only accessed by a single thread. … Read more ›...

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12: Hibernate custom data type : Blob type example

There are times you want to define a custom data type in Hibernate. Here is an example of using a custom ImageType defined as a Blob databse type to store images, excel files, etc.

Step 1: Define the custom Hibernate data type “ImageTpe”

…

12: JMockit interview Q&As & examples on matching with(Delegate)

JMockit offers a set of utility fields & methods for making argument matching more generic. 1) anyX fields like anyInt, anyBoolean, anyString, etc. There is one for each primitive type, and the corresponding wrapper class, … Read more ›...

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13: Atomicity, Visibility, & synchronization in Java

Q. Given the following code, Client


package com.homeassignment.task5;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.locks.LockSupport;

public class Client {

    private AtomicInteger requestCount = new AtomicInteger(0);
    private AtomicInteger processedCount = new AtomicInteger(0);

    private Service service = null;

    public static void main(String[] args) {
        new Client().execute();
    }

    private void execute() {

        service = new ServiceImpl();
        int concurrentUsers = 25;
        int requestsPerUser = 10;

        final ExecutorService executorService = Executors.newFixedThreadPool(concurrentUsers, new ThreadFactory() {
            private AtomicInteger threadCnt = new AtomicInteger(0);

            @Override
            public Thread newThread(Runnable r) {
                final Thread thread = new Thread(r, "Thread " + threadCnt.incrementAndGet());
                thread.setDaemon(true);
                return thread;
            }
        });

        for (int i = 1; i <= concurrentUsers; i++) {
            executorService.submit(new Runnable() {
                @Override
                public void run() {
                    for (int j = 1; j <= requestsPerUser; j++) {
                        service.process("Request-no-" + requestCount.incrementAndGet()); //invoking a service
                        processedCount.incrementAndGet(); 
                    }
                }
            });
        }

        while (processedCount.get() < requestCount.get()) {
            LockSupport.parkNanos(TimeUnit.MILLISECONDS.toNanos(20));
        }

        executorService.shutdown();
    }
}

package com.homeassignment.task5;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

import java.util.concurrent.ThreadFactory;

import java.util.concurrent.TimeUnit;

import java.util.concurrent.atomic.AtomicInteger;

import java.util.concurrent.locks.LockSupport;

public class Client {

private AtomicInteger requestCount = new AtomicInteger(0);

private AtomicInteger processedCount = new AtomicInteger(0);

private Service service = null;

public static void main(String[] args) {

new Client().execute();

}

private void execute() {

service = new ServiceImpl();

int concurrentUsers = 25;

int requestsPerUser = 10;

final ExecutorService executorService = Executors.newFixedThreadPool(concurrentUsers, new ThreadFactory() {

private AtomicInteger threadCnt = new AtomicInteger(0);

@Override

public Thread newThread(Runnable r) {

final Thread thread = new Thread(r, "Thread " + threadCnt.incrementAndGet());

thread.setDaemon(true);

return thread;

}

});

for (int i = 1; i <= concurrentUsers; i++) {

executorService.submit(new Runnable() {

@Override

public void run() {

for (int j = 1; j <= requestsPerUser; j++) {

service.process("Request-no-" + requestCount.incrementAndGet()); //invoking a service

processedCount.incrementAndGet();

}

});

}

while (processedCount.get() < requestCount.get()) {

LockSupport.parkNanos(TimeUnit.MILLISECONDS.toNanos(20));

}

executorService.shutdown();

}

Service interface & implementation


package com.homeassignment.task5;

public interface Service {
    void process(String requestId);
}

package com.homeassignment.task5;

public interface Service {

void process(String requestId);

}


package com.homeassignment.task5;

import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.LockSupport;

public class ServiceImpl implements Service {

    @Override
    public void process(final String requestId) {
        System.out.println("Started processing = " + requestId);
        // emulating actual processing
        LockSupport.parkNanos(TimeUnit.MILLISECONDS.toNanos(2000)); //XXX expensive call to a legacy system                                          
        System.out.println("Finished processing = " + requestId);
    }
}

package com.homeassignment.task5;

import java.util.concurrent.TimeUnit;

import java.util.concurrent.locks.LockSupport;

public class ServiceImpl implements Service {

@Override

public void process(final String requestId) {

System.out.println("Started processing = " + requestId);

// emulating actual processing

LockSupport.parkNanos(TimeUnit.MILLISECONDS.toNanos(2000)); //XXX expensive call to a legacy system

System.out.println("Finished processing = " + requestId);

}

the line “XXX expensive call to a legacy system” in the “ServiceImpl” is an external call to a legacy system, which breaks when more than 5 concurrent calls are made. … Read more ›...

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13: JMockit interview Q&As & examples on Deencapsulation utility class

This extends JMockit interview Q&As & examples on Partial Mocking with MockUp. What is Deencapsulation utility class used for? Mocking and testing of private methods or inner classes is often not considered good practice. Earlier we had looked at the Faking API with MockUp<T> to mock private methods. … Read...

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14: JMockit interview Q&As & examples on Mocking a super class

There are times you want to Mock the superclass & test only the subclass. Superclass that should not be invoked The BaseService.java:

package com.myapp;

public class BaseService {

    public BaseService(){
        throw new IllegalArgumentException("Should not reach here");
    }
}

package com.myapp;

public class BaseService {

public BaseService(){

throw new IllegalArgumentException("Should not reach here");

}

Subclass to be tested The MyService.java:

package com.myapp;

public class MyService extends  BaseService {

    private int num1;
    private int num2;

    public MyService(int num1, int num2) {
       super();
       this.num1 = num1;
       this.num2 = num2;
    }

    public int eval() {
        return num1 + num2;
    }
}

package com.myapp;

public class MyService extends BaseService {

private int num1;

private int num2;

public MyService(int num1, int num2) {

super();

this.num1 = num1;

this.num2 = num2;

}

public int eval() {

return num1 + num2;

}

JUnit test class The BaseService.java will be mocked as shown below. … Read more ›...

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15 Database design interview Q&As

Q1. What is normalization? When to denormalize? A1. Normalization is a design technique that is widely used as a guide in designing relational databases. Normalization is essentially a two step process that puts data into tabular form by removing repeating groups and then removes duplicated data from the relational tables....

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15 Ice breaker interview Q&As asked 90% of the time

Most interviews start with these 15 open-ended questions. These are ice breaker interview questions with no right or wrong answers to ease nervousness, but the quality of the answers can make a good first impression. Your answer can reveal a lot about your experience &

…

15 Security key area interview Q&A for Java developers

Q1. Can you provide a high level overview of the “access control security” in a recent application you had worked? A1. As shown below, SiteMinder is configured to intercept the calls to authenticate the user. Once the user is authenticated, a HTTP header “SM_USER” is added with the authenticated user...

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15: JMockit interview Q&As & examples on Mocking a Singleton

We often write code that depends on Singletons. Writing unit tests in this case could be tricky. Here is an example demonstrating how to solve the problem with JMockit. Is Singleton pattern an anti-pattern? The Singleton pattern is a design pattern that restricts the instantiation of a class to one...

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15+ Amazon EC2 instances interview Q&As

Q01. What is an Amazon EC2 Service? A01. EC2 stands for Elastic Cloud Computing that provides resizable (i.e. scalable) computing capacity in the cloud. You can use Amazon EC2 to launch as many virtual servers as you need. In EC2 you can configure security and networking as well as manage...

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15+ AWS Services overview interview Q&As

Below questions are based on the above diagram, and extends AWS Q&As on VPC, Subnets, Availability Zones, VPN, Route tables, NACLs & Security Groups: Q1. What is the difference between CloudWatch & CloudTrail? A1. Both provide logging capabilities. … Read more ›...

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15+ SQL optimisation interview questions & answers with scenarios

1) Select fields instead of using SELECT *. The “*” is used as a short hand to query all available data from a table. If a table has many fields and rows, this takes database resources by querying a lot of unnecessary data. … Read more ›...

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Categories

Blog Archives

12: Complete the trades matching logic

12: Hibernate custom data type : Blob type example

12: JMockit interview Q&As & examples on matching with(Delegate)

13: Atomicity, Visibility, & synchronization in Java

13: JMockit interview Q&As & examples on Deencapsulation utility class

14: JMockit interview Q&As & examples on Mocking a super class

15 Database design interview Q&As

15 Ice breaker interview Q&As asked 90% of the time

15 Security key area interview Q&A for Java developers

15: JMockit interview Q&As & examples on Mocking a Singleton

15+ Amazon EC2 instances interview Q&As

15+ AWS Services overview interview Q&As

15+ SQL optimisation interview questions & answers with scenarios

300+ Java Interview FAQs

300 + Big Data Interview FAQs

16+ Java Tech Key Areas

10+ Companion Techs Q&As

300+ Java Interview Q&As

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