What is the difference between a Set and a Map in Java?

Main differences between a Set and a Map in Java are:

Duplicate Elements: A Set does not allow inserting duplicate elements. A Map does not allow using duplicate keys, but it allows inserting duplicate values for unique keys.
Null values: A Set allows inserting maximum one null value. In a Map we can have single null key at most and any number of null values.
Ordering: A Set does not maintain any order of elements. Some of sub-classes of a Set can sort the elements in an order like LinkedHashSet. A Map does not maintain any order of its elements. Some of its sub-classes like TreeMap store elements of the map in ascending order of keys.

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AirBnB Infographic Journey to IPO

Full Post at https://techpomelo.com/2020/10/infographics-airbnb-milestone-journey-to-ipo/

C Program to find factorial of a number using functions.

#include<stdio.h> #include<conio.h> void main() { int a,f; int fact(int); clrscr(); printf(“enter a no: ”); scanf(“%d”,&a); f=fact(a); printf(“factorial= %d”,f); getch(); } int fact(int x) { int fac=1,i; for(i=x;i>=1;i--) fac=fac*i; return(fac); }

8 common methods for server performance optimization

1. Use an in-memory database In-memory database is actually a database that puts data in memory and operates directly. Compared with the disk, the data read and write speed of the memory is several orders of magnitude higher. Saving the data in the memory can greatly improve the performance of the application compared to accessing it from the disk. The memory database abandoned the traditional way of disk data management, redesigned the architecture based on all data in memory, and made corresponding improvements in data caching, fast algorithms, and parallel operations, so the data processing speed is faster than that of traditional databases. Data processing speed is much faster. But the problem of security can be said to be the biggest flaw in the memory database. Because the memory itself has the natural defect of power loss, when we use the memory database, we usually need to take some protection mechanisms for the data on the memory in advance, such...

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