Blog Archives
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00: Tree from a list & flattening it back to a list in Java

Hierarchical data with parent & child relationships are very common, and Java collection does not have a Tree data structure, hence it is a popular interview question. Further questions include tree data structure processing using recursiion & iteration. A Tree data structure can be represented as shown below.

Step 1:



01: Can you design classes & interfaces using OO?

Q1. How would you go about designing a “farm animals” application where animals like cow, pig, horse, etc move from a barn to pasture, a stable to paddock, etc? The solution should also cater for extension into other types of animals like circus animals, wild animals, etc in the future…. …



01: String parsing & date formatting – complete the given code

Q. Complete the method “changeDateFormat(String paragraph)” which takes a string input containing dates in mm/dd/yyyy format and converts them to “dd/mm/yyyy” format. For example, “My birthday is on 04/25/1980” becomes “My birthday is on 25/04/1980



01: Tree flattening example in Java

Q. Traverse the tree in depth and return a list of all passed nodes. It should handle different data types as Double, String, etc. The4 interface for the tree node is



01: What is wrong with following Java code snippets? Auto-unboxing, switch, short circuit & exception

Auto-unboxing, switch, short circuit logical operators & exception handling are core Java basics that sometimes lead to obscure errors if not understood well & often tested in coding tests.

Q1. What is wrong with this code?



02: Scenarios based Java OO concepts & GoF design patterns – naive Template Method pattern

Extends Can you design classes & interfaces using OO?. Only experience, and asking the right questions can teach you what design pattern to use, in which scenario.

Scenario: A company named XYZ Retail is in the business of selling Books, CDs and Cosmetics. Books are sales tax exempt and …



02: Tree structure – calculate average recursively & iteratively in Java

Q. Complete the following “TreeProcessingImpl” class ….. so that the unit tests shown below pass? Skeleton Code



02: Working with Java Collections – Complete the given code

Q. Complete the method “canAttendAll(Collection seminars)” which takes a collection of seminar objects with start and end timestamps, and the method should determine if there is an overlap in seminars events. In other words, if you can attend all the seminars.



03: Scenarios based Java OO concepts & GoF design patterns – Strategy Pattern

The following post improves on the design flaws listed in the previous post entitled 02: Scenarios based Java OO design & GoF design patterns – naive Template Method pattern. Scenario: A company named XYZ Retail is in the business of selling Books, CDs and Cosmetics. Books are sales tax exempt… …



03: Tree navigation – is a BST Tree?

Q. Complete the method “isValidBST(Node root)” which takes a “Tree node” as an input to evaluate if the input is a valid BST (i.e. Binary Search Tree)?



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Java developer & architect Q&As

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