200+ Java Fullstack developer questions

1. Write Fibonacci series programming and explain logic
2. how auto wiring works in spring
3. write a program for dependency injection
4. how security is implemented in your project.
5. difference between filter and map in java streams.
6. Explain about your current project.
7. How to read the file and display total count of each word.
8. How angular Makes calls to spring boot
9. What is spring profile
10. There is a list with emp objects with duplicate name, age attributes. How to retrieve uniques names.
11. What Technologies used in last project.
12. Abstract class and encapsulation.
13. What is HashMap? how it works.
14. what is inter thread communication
15. what ArrayList ? extends object and ArrayList? super object means
16. what is splice and slice
17. difference between == and ===
18. Write a Java 8 program to get the sum of all numbers present in a list?
19. what FlatMap?
20. write a prog ..how to sort emp obj in java8
21. Given the list of employees, find the employee with name “R”.
22. Angular Routing process
23. Difference Between constructor vs ngOnInit in Angular
24. how to find which datatype is created in JavaScript
25. what is id in CSS
26. how to create a singleton object
27. what is static method, static block and static class
28. what will happen if we add final to a method
29. what is @path and path param, path variable
30. what is multi catch block
31. what is subquery and when we use it
32. how to use service in angular
33. difference between @Input and @Output in angular
34. what is event emitter
35. what is @beanpropertyrowmapper
36. Handle cross horizon resource sharing-angular, how can u candle hash code, equal
37. sql query, highest salary- department wise
38. Routing in Angular
39. import and export in ngModule
40. what is ngModule
41. directives and use of them in angular
42. routes in angular
43. what is children attribute in routes in angular
44. Hibernate OneToMany and ManyToOneMapping example
45. How to return a single user if userId passed or list of users if userId not passed in JPA
46. Micro services communication
47. Autorization and authentication process in current project
48. String reverse program
49. Spring JPA Example
50. Factory design pattern
51. Singleton Design pattern and real time usage and implementation
52. How to prevent singleton object from clone?
53. Synchronous and asynchronous requests, how to consume angular http request and services
54. Springcloud config
55. publishing a service in spring cloud
56. diff b\w rest and soap
57. what is the new in the current java version compared with previous versions?
58. What is the lambda expression?
59. What is a functional interface and it’s example?
60. How many ways to create a thread and it’s life cycle?
61. What are streams in java?
62. What is the difference between a hashset and concurrenthashset?
63. Difference between hashmap and concurrenthashmap
64. What is LinkedHashMap
65. What is a static method in java?
66. How the static class locking works?
67. what is a singleton design pattern and how do you create it?
68. What are directives in angular?
69. What are pipes in angular?
70. How do components communicate with each other and data transfer among them?
71. What is DDL and DML??
72. What is the difference between Truncate and Delete?
73. What is the difference between function and procedure?
74. What is immutable class
75. Method to find missing number in a Array list with value from 0-100. (number 7 and are missing)
76. find the number of integer appear in a array list having duplicates
77. Explain Quick sort
78. Serialization
79. what is executer framework and cachethreadpool
80. How hashMap works internally
81. Spring & Microservice
82. What is microservice and its architecture
83. How to handle situation if one of microservice fails
84. What is API gateway
85. What is client side load balancing
86. Spring life cycle
87. What is dependency Injection
88. Annotation used in circuit breaker implementation
89. Microservice design patterns
90. fast iterate and safe iterate
91. How you read file from angular
92. difference between get and load in hibernate
93. Spring JPA CRUD Repository
94. jdbcTemplate methods
95. difference between Observer and subscribe in angular
96. Spring boot and hibernate integration steps
97. How you read properties file from springboot
98. sql query for one to many mapping.
99. Functional interface.
100. Design patterns used Realtime in your application.
101. Java Multithreading – wait & notify, Obtaining lock.
102. Static and Dynamic Overloading.
103. Spring security its annotations.
104. Java 1.8 features.
105. Angular Observable subscribe and unsubscribe.
106. what happens when we call a void method in a system.out.println()?
107. What is Resource(Request) and Response in Restful services?
108. how can I return custom data instead of JSON or XML content for a Rest response?
109. what are stream(s) in java and few operations on them like comparison
110. difference between comparable and comparator
111. why Clonable is not implemented by Collection interface, reason?
112. Components in angular
113. What is the life cycle of components in angular
114. Sharing data between components in Angular
115. Type Script compilation process
116. Angular life cycle
117. what are gate in angular
118. in how many ways I can sort my employee object with the given set of columns, explain?
119. How to create schedulers in java
120. How we implement batch import and export functionality in spring.
121. How to maintain session in server side.
122. Lifecycle process of angular
123. How to reload header and footer menu based on particular left menu routing
124. Box model in CSS
125. Pseudo selector in CSS
126. Difference between display block & display inline-block
127. Difference between position absolute and position relative
128. What is the internal implementation of HashMap?
129. What is the algorithm/datastructure used to get an emlement from HashMap?
130. How to make HashMap synchronized
131. Difference between HashMap & concurrent hash map
132. Authenticate client side in angular
133. Time difference calculation in angular
134. How to create Generic class in angular
135. Difference between Post and PUT
136. Stored Procedures
137. Monolithic architecture and Microservice Architecture
138. java 8 new features
139. List of collections used
140. How exceptions are handled
141. Throw and Throws
142. Final, Finally, Finalize
143. Spring IOC
144. Spring boot advantages
145. JPA repository
146. First level second level cache in hibernate
147. Union vs Union all
148. Spring security
149. Spring transactions
150. Custom directives
151. Get and post in angular
152. employee has id, name, salary. Find the list of employees where the employee name starts with “n” using java8?
153. can you the same in ArrayList and array?
154. Vulnerability checking process in the front end
155. Have you worked on Cross Site Scripting?
156. What are the challenged faced in Cross Site Scripting?
157. Have you worked in Custom annotation creation in Java?
158. if yes? Could you explain the implementation of custom annotation?
159. Where thread class variables will get store in Memory?
160. What are the different databases you worked?
161. Did you face any query performance issues? how did you increase the performance of the query?
162. What is index and query of it?
163. What is the data structure used to create an index?
164. How can you handle the errors in Spring Boot?
165. Can you explain what are the dependencies required to create REST application in Spring Boot? what other classes needs to be created to perform CURD operations and it’s flow?
166. How you worked on application security?
167. angular life cycle hooks
168. Explain insertion sort logic
169. Write query to get 3rd highest salary of employee
170. How to get the average value of integers using streams
171. What are method references
172. What are for lambda expressions introduced and what is the advantage
173. explain proxy pattern
174. how to find duplicate user object user {name, age}
175. What is observable
176. What is cluster index
177. What is the deployment procedure of Micro services
178. Explain service discovery pattern
179. What is containerization
180. how to import module and service in Angular
181. Difference between monolithic and microservices architecture.
182. Difference between Spring and Spring boot
183. Explain about Spring boot starter
184. Spring security
185. @Springboot application
186. Gates in angular
187. Life cycle of angular hooks
188. How to pass the data between components.
189. Structural and behavioral directives
190. Multi threading concepts
191. Architecture of the current project where you are working
192. Architecture of angular application
193. Difference between soap and Rest
194. Questions on GIT code checkout process
195. Questions on Front end security concepts
196. Code deployment procedure
197. Load balancing concepts related to services
198. REST and SOAP justification for usage
199. Questions based on resume and projects explanation Why ? What ?
200. How we used if we mention any technology

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Java : Lambda Expression

What is Lambda expression?

As per Wikipedia, lambda expression also called as anonymous function. It’s a function without name and does not belong to any class. Lambda expression is introduced as part of Java 8 features.

A traditional method or function in java has these main parts.

• Name
• Parameter list
• Body
• Return type

A lambda expression in java has these main parts.

• No Name: as this is anonymous function there is no name needed
• Parameter list
• Body: this is the main part of the function
• No return type: you don’t need to mention the return type in lambda’s expression. The java 8+ compiler is able to infer the return type by checking the code.

Program of using lambda expression without any parameters:

@FunctionalInterface
interface NoParamInterface{
    String printHelloWorld();
}

public class NoParamLambdaTest{
    public static void main(String[] args) {
        NoParamInterface noParamInterface= () -> "Hello World";
        System.out.println(noParamInterface.printHelloWorld());
    }
}

Program of using Lambda expression with single parameter:

@FunctionalInterface
interface SingleParam{
    int incrementBy10(int x);
}

public class SingleParamLambdaTest {
    public static void main(String[] args) {
        SingleParam singleParam = (x) -> x+10;
        System.out.println(singleParam.incrementBy10(5));
    }
}

Program of using Lambda expression with multiple parameters:

@FunctionalInterface
interface MultiParam{
    String concat(String x, String y);
}

public class MultiParamLambdaTest {
    public static void main(String[] args) {
        MultiParam multiParam = (x, y) -> x+" "+y;
        System.out.println(multiParam.concat("Hello", "World"));
    }
}

Program of using Lambda expression with Runnable interface:

public class RunnableExample {

    public static void main(String[] args) {
        //Traditional way of implementation
        Runnable runnable = new Runnable() {
            @Override
            public void run() {
                int sum=0;
                for(int i=0;i<10;i++)
                    sum +=i;
                System.out.println("Traditional : "+sum);
            }
        };
        new Thread(runnable).start();

        //Implementing using lambda
        Runnable runnable1 = () -> {
            int sum=0;
            for(int i=0;i<10;i++)
                sum +=i;
            System.out.println("Lambda : "+sum);
        };
        new Thread(runnable1).start();

        //Implementing Thread with Lambda
        new Thread(()->{
            int sum=0;
            for(int i=0;i<10;i++)
                sum +=i;
            System.out.println("Thread with Lambda : "+sum);
        }).start();
    }
}

Program of using Lambda expression with Callable interface:

import java.util.Arrays;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.stream.IntStream;

public class CallableExample {
    public static int[] array = IntStream.range(0,5000).toArray();
    public static int count = IntStream.range(0,5000).sum();

    public static void main(String[] args) throws InterruptedException, ExecutionException {
        Callable<Integer> callable1 = () -> {
            int sumOfEven=0;
            for(int i=0;i<array.length;i++){
                if(i%2 == 0)
                    sumOfEven = sumOfEven + i;
            }
            return sumOfEven;
        };

        Callable<Integer> callable2 = () -> {
            int sumOfOdd=0;
            for(int i=0;i<array.length;i++){
                if(i%2 == 1)
                    sumOfOdd = sumOfOdd + i;
            }
            return sumOfOdd;
        };

        ExecutorService executorService = Executors.newFixedThreadPool(2);
        System.out.println("Sum of Even of given range: "+executorService.invokeAny(Arrays.asList(callable1)));
        System.out.println("Sum of Odd of given range: "+executorService.invokeAny(Arrays.asList(callable2)));
        executorService.shutdown();

        System.out.println("Count of the given range is : "+count);
        System.out.println("Sum of Odd and Even is equals to count");
    }
}

How InOut parameter will work in java?

Objective:
Objective of this article is to explain How references will work in java or How InOut parameter will work in Java?

Explanation:
We studied in C language the importance of  pointers similarly we need to know how references are working in java. Without knowing how object references are working in java, we cant understand application flow properly.

Lets take one example in java related to references as well as InOut parameter in java.

class Student{ 
     private Integer id; 
     private String name; 
     //setter and getter 
 } 
 class Main{ 
     public static void main(String arg…){ 
         Student s1=new Student(); 
         System.out.println(s1.getId()); 
         System.out.println(s1.getName()); 
         m1(s1); 
         System.out.println(s1.getId()); 
         System.out.println(s1.getName()); 
     } 
     public static void m1(Student s3){ 
         s3.setId(10); 
         s3.setName("ranga"); 
         s3=null;
     } 
 }

In the above program we used new keyword only one time so entire program will have only one student object created.

Once we create object s1 is pointing to that object and its id,name values initialize with null values like the below screenshot.

When we execute the below code, it will return with null value.

System.out.println(s1.getId());//null 
System.out.println(s1.getName());//null

When we call m1(s1); then Student s3=s1; then s3 reference also pointing to same object which is already referred by s1 reference. Look at the below image,

When we execute s3.setId(10); and s3.setName(“Ranga”); then s3 reference id value(null) override with 10 and name value(null) override with “Ranga”. Look at the below diagram,

When we do s3=null then it will lost the connection with that reference and m1 method execution is over because it doesn’t return anything because of it’s return type is void. Look at the below diagram,

The below diagram illustrates, that the previously setting s3 values are pointing to s1 because s3 lost connection with them.

Now it we print id and name of s1 reference, it will print id as 10 and name is “Ranga” because s1 is pointing to Student object which has the values of 10 and “Ranga”.

I hope this helped you to understand about references in Java. Let us know your thoughts. Happy Learning 🙂