Desarrollador Java Interview Questions

Desarrollador Java Interview Questions

En una entrevista para un puesto de desarrollador Java, prepárate para responder preguntas técnicas destinadas a evaluar tus conocimientos básicos de Java. El posible que también te formulen preguntas abiertas para evaluar tus habilidades de programación y de resolución de problemas. Prepárate para afrontar preguntas no técnicas centradas en tus habilidades de comunicación interpersonal, de organización del tiempo y de ética en el trabajo.

Preguntas de entrevista más frecuentes para desarrollador/a Java y cómo responderlas

Question 1

Pregunta n.º 1: ¿Cuál es la diferencia entre HashTable y HashMap en Java?

How to answer
Respuesta recomendada: Los entrevistadores usarán preguntas técnicas para evaluar tu cualificación formal y tus conocimientos del lenguaje de programación Java. Aprovecha tu respuesta para exponer tus habilidades de comunicación. Aunque lleves años programando, quizás te convenga repasar tus nociones básicas de Java antes de la entrevista.
Question 2

Pregunta n.º 2: Escribe un programa para determinar si 243 es un número Armstrong.

How to answer
Respuesta recomendada: Usarán preguntas abiertas para poner a prueba tus habilidades de programación. Esta pregunta permite evaluar tu capacidad para resolver un problema utilizando un algoritmo de Java. Explica tu planteamiento mientras utilizas un editor de código o pizarra.
Question 3

Pregunta n.º 3: ¿Cómo lograrías elaborar código de calidad si tuvieras que simultanear varios proyectos Java?

How to answer
Respuesta recomendada: Los desarrolladores Java a menudo tienen que trabajar en varios proyectos a la vez. Las personas que realizan la entrevista utilizan preguntas como esta para poner a prueba tus habilidades organizativas y de gestión. Las empresas también intentan evaluar tu compromiso de calidad con tu trabajo. Si tienes experiencia como desarrollador, incluye ejemplos de tu experiencia profesional que demuestren tu capacidad para producir trabajo de calidad y para gestionar el tiempo de manera eficiente.

710,987 desarrollador java interview questions shared by candidates

u have 10 red socks and 10 blue in ur cupboard .you have to take 1 pair of socks but ur room is completely dark.how many minimum no. of socks required to take so that u ll be sure to get atleast a pair of same coloured socks?
avatar

Software Engineer

Interviewed at e-con Systems

3.8
Mar 4, 2017

u have 10 red socks and 10 blue in ur cupboard .you have to take 1 pair of socks but ur room is completely dark.how many minimum no. of socks required to take so that u ll be sure to get atleast a pair of same coloured socks?

Coding challenge: 1. You are given a matrix of Ys and Ns where a Y at (i,j) denotes that persons i and j are friends. Friendships are transitive, so if A is a friend of B is a friend of C, then A is in the same a friend circle as C even if A doesn't know C directly. How many friend circles are there? It's really a disjoint sets problem. 2. You are given a list of strings. Removing a letter from any string yields a different string that may or may not exist in the list as an independent entity. This is one link of a "string chain". Find the longest chain in the array. Solved with a hashtable. Interview day: 1. Code a function that matches regular expressions with targets. There is a DP and a recursive solution. 2. Test it extensively in a main. Write a function to autogenerate test cases. 3. Code a postfix notation calculator. Doable with a stack. Now, what if you wanted to support arbitrary operations on some variable number of preceding numbers? How does the code change? 4. You are given a tree in the form of a list of (value, parentndx, intree) tuples, where intree is a boolean denoting whether the node is in the tree, and parentndx is the location in the list of the parent node of this node. The root's parent is -1. Write a function remove(ndx) that removes the node at that ndx and all its children in O(n). It requires caching which nodes have been visited and a recursive function that checks whether a node in the list should be removed (terminates on parentndx==-1 || ndx or when it finds a cached node that was already removed and visited). 5. You are given two infinite streams of data, where each datum has fields (timestamp, value). The streams have a single function take() that pops the oldest thing off and returns it or "blocks" until something arrives in the queue for it to return. Data might arrive much later than its timestamp. You are given a function output(a,b), which takes two values, one from each stream, and computes something. You want to call output() on all (a,b) pairs that have timestamps less than some given interval apart, and you want to do this as soon as any data that completes such a pair arrives. Construct pseudocode that will do this. The answer involves two threads that each manage a list of numbers pulled off their stream, pull a number from the other thread's list, try to match it against everything, and then carefully discard data when appropriate. 6. You are managing a webservice and get a complaint about the page loading slowly. What is a possible cause of the problem? How would you check that? Okay, say that's not the problem. What else could it be?
avatar

Software Engineer

Interviewed at Two Sigma

3.9
Feb 23, 2017

Coding challenge: 1. You are given a matrix of Ys and Ns where a Y at (i,j) denotes that persons i and j are friends. Friendships are transitive, so if A is a friend of B is a friend of C, then A is in the same a friend circle as C even if A doesn't know C directly. How many friend circles are there? It's really a disjoint sets problem. 2. You are given a list of strings. Removing a letter from any string yields a different string that may or may not exist in the list as an independent entity. This is one link of a "string chain". Find the longest chain in the array. Solved with a hashtable. Interview day: 1. Code a function that matches regular expressions with targets. There is a DP and a recursive solution. 2. Test it extensively in a main. Write a function to autogenerate test cases. 3. Code a postfix notation calculator. Doable with a stack. Now, what if you wanted to support arbitrary operations on some variable number of preceding numbers? How does the code change? 4. You are given a tree in the form of a list of (value, parentndx, intree) tuples, where intree is a boolean denoting whether the node is in the tree, and parentndx is the location in the list of the parent node of this node. The root's parent is -1. Write a function remove(ndx) that removes the node at that ndx and all its children in O(n). It requires caching which nodes have been visited and a recursive function that checks whether a node in the list should be removed (terminates on parentndx==-1 || ndx or when it finds a cached node that was already removed and visited). 5. You are given two infinite streams of data, where each datum has fields (timestamp, value). The streams have a single function take() that pops the oldest thing off and returns it or "blocks" until something arrives in the queue for it to return. Data might arrive much later than its timestamp. You are given a function output(a,b), which takes two values, one from each stream, and computes something. You want to call output() on all (a,b) pairs that have timestamps less than some given interval apart, and you want to do this as soon as any data that completes such a pair arrives. Construct pseudocode that will do this. The answer involves two threads that each manage a list of numbers pulled off their stream, pull a number from the other thread's list, try to match it against everything, and then carefully discard data when appropriate. 6. You are managing a webservice and get a complaint about the page loading slowly. What is a possible cause of the problem? How would you check that? Okay, say that's not the problem. What else could it be?

It's the first OA coding sample of Google. The coding question is: Given a zero-indexed array A of N integers, return any of the indexes P of the element, which left sums of its left elements and right elements are equal. Sum of zero element is assumed to be equal to 0. This can happen if P = 0 or if P = N-1.For example, A = {-1, 3, -4, 5, 1, -6, 2, 1}, indexes 1, 3, and 7 are valid outputs.
avatar

Software Engineer

Interviewed at Google

4.4
Jun 23, 2016

It's the first OA coding sample of Google. The coding question is: Given a zero-indexed array A of N integers, return any of the indexes P of the element, which left sums of its left elements and right elements are equal. Sum of zero element is assumed to be equal to 0. This can happen if P = 0 or if P = N-1.For example, A = {-1, 3, -4, 5, 1, -6, 2, 1}, indexes 1, 3, and 7 are valid outputs.

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