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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 &

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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, … Read...

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

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01: Tree flattening example in Java with Generics

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

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.


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

Scenarios based Java OO concepts & GoF design patterns

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 Unit Tests A. … Read more ›...

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...

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. …...

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)? … Read more...

03: Tree traversal algorithms in Java

Q1. What are the different binary tree traversal mechanisms? A1. Traversing a tree means visiting all the nodes of a tree in order. … Read more ›...

03: Understanding Big O notations with Java

Q1.  Have  you seen job advertisements requiring Java candidates to work in real-time or high volume transaction processing systems? A1.  If you are applying for such jobs, … Read more ›...

03: What is wrong with this code? Data types & equals( ) Vs, hashCode( ) contract

Q6. What is wring with this code?

A6. Infinite loop at due to sum != 1.0. Using floating point variables like float or double in loops to compare for equality can lead to infinite loops.

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