Java Essentials - Priority queue in java

In this video we are discussing priority Q in Java

So this priority Q, like the previous video we have discussed Q, this priority Q does not support

that first in first out or last in last out data structure

It arranges our data according to the priority, based on the priority

So now let me discuss more on this priority queue in our discussion

So the priority Q in Java collection, the priority Q does not follow the FIFO rule

unlike the normal queue with whatever we have discussed in the earlier video

So it arranges the elements based on their priorities. So depending upon the priorities, the elements will be arranged

Priority queue can store comparable objects to arrange them in the correct priorities

It has the method like add, remove, etc. And also it has pole method that is used to retrieve and remove the element from the head of the queue

So these are the different methods we have discussed. I think to clear our conception in a better way, let us go for one practical demonstration

where it will be discussing more on this priority queue. The demonstration is coming next

When you define one class which is implementing comparable interface, you can write a

sample code for you. So class, say ST implements. comparable so here I putting this one as ST then you can find that as it is one interface it is having some unimplemented methods if you go on adding this unimplemented method we getting the method that is a compared to so compared to will take the class object

ST class object as input and it returns one integer so we are supposed to write

the rewrite the code or the body for this compared to method so we have applied

the same here so let me go for my coding so class student implements comparable

student so private I nt rank and private string name so these two are instance

variable one is a rank another one is the name of the type I and string class

objects so this is our student is the constructor which will take this name and

rank as input parameters and they will get input arguments and they will

instantiate this instance variable that is that this dot rank and this dot name

now this is a comparative which is there unimplemented this interface that is a comparable so comparable is nothing but one

interface you can find it here and it is defined under the package is java

dot lang so these are compared to we have written so this is about a input

argument will be one student class object so let it be ST so it will compare

the rank of the student with another student so if rank is less than

ST dot rank then return minus one else if rank is greater than

st.d rank then return one otherwise return zero so depending upon the value of this this dot rank and ST dot rank

the either minus 1 or 1 or 0 will be returned as I have shown here also we are overriding the method that is a two string so there is a string result is equal to student name concatenation name concordination rank and concordination

rank here and return results so string will be returned as the output

argument for this two string method so now here we have defined one class that is

a priority queue under this class we have defined the main function so priority

Q class object there is a student Q the and which will hold the student class

objects as its elements so student class we have defined here so it is nothing but

implementing the comparable interface and we also have overridden and the respective method compared to so priority Q is not nothing but the name of the

class and then student is the the respective objects which will be which will be

deciding in this priority Q object that is a student Q as items and is equal to

new priority queue we are calling the constructor here so student Q volte add so using this ad method we can go on adding or inserting new students into this priority Q so here we are having this Ashish there is a name and five is the respective role a rank rather you can say so here you see this this is my rank will be there and the name is there at first I'm passing this name as input parameter and rank as the second parameter here so name is Ashish rank is five name is borun rank is three you can

easily call that this student is actually implementing this comparable interface so

what will happen when they will get inserted so they will remain short it

accordingly depending upon the rank of the student so here you see we are here we have added five such student items here so insert students into the priority queue and part when we shall go for the

the printing of its content will be finding them in the short-ed order so we

shall come that point later so at first we are going to print the size of this

student queue as we have inserted five items so the size of the queue will be

five here now we are creating one iterator to iterate through this queue so iterator IT is equal to student q

iterator now we know that we are having the method that is a has next which is

returning a bullion so IT dot has next so when they it is true then we are

printing this student q.poll dot two strings so in this way you are just

printing this one so student q.poll so we are retrieving each and every

element from here for each and every iteration and then we are just calling this method two string which we have over-readed here which will

print the name and the ranked accordingly remember we entered and inserted and this

new elements got added to this student queue in the order that is a sish 5 then

boron 3 then Monish 1 then show week 4 and Rahul 2 so in the execution you

are finding that they're coming like the Monish 1 with the rank 1 has come at the

first then Rahul with the rank 2 then boron with the rank 2 then borun with the 3 then show week with the rank 4 and Ashish with the respective rank 5 here in this

way we have given you the idea that how to deal with the priority Q class

objects in our Java code thanks for watching this video