KONE Junior Engineer - Maintenance Interview Questions and Answers

There were 4 sections and first one was quant, second one was logical, third was English and finally 3 coding questions in last section

4 codes and 5 technical questions

Q1. Explain multi threading
Ans. 
Multi threading is the ability of a CPU to execute multiple threads concurrently.
• Allows for parallel execution of tasks, improving performance

• Each thread has its own stack and runs independently

• Threads can communicate and synchronize using shared memory

• Examples: running multiple tasks simultaneously in a web server, processing data in parallel
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Q2. What is polymorphism
Ans. 
Polymorphism is the ability of a single function or method to operate on different types of data.
• Polymorphism allows objects of different classes to be treated as objects of a common superclass.

• It enables a single interface to be used for different data types.

• Examples include method overloading and method overriding in object-oriented programming.
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Q3. Diff b/w inner and outer joins
Ans. 
Inner join returns only the rows that have matching values in both tables, while outer join returns all rows from both tables.
• Inner join: returns rows with matching values in both tables

• Outer join: returns all rows from both tables, with NULL values where there is no match

• Example: Inner join - SELECT * FROM table1 INNER JOIN table2 ON table1.id = table2.id

• Example: Outer join - SELECT * FROM table1 LEFT OUTER JOIN table
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