Oracle HR reached out based on job portal details.

Initial impression was that the focus would be more on DSA, but surprisingly, it was more on Java.

In-depth Java knowledge was expected.

Total of 4 rounds.

What is synchronization?

How is memory management done in Java? Why are only the heap and stack used in Java?

String immutability: why is it called that? What happens when you store a variable?

What is System.out.print?

What are static variables and why are they used? static vs. non-static.

Object class functions like toString(): give examples and explain how they are implemented.

What are HashCode and equals?

What is the Singleton design pattern? Write code for it. How would you scale if more instances needed to be added?

DSA: Given (a,b) and (c,d), you can add b to a and a to b, such that a=c, b=d. If this pair is possible, return true using recursion.