Ascending Priority Queue implementation in java

import java.io.*;
class Node
{
 int data;
 int priority;
 Node link;
  Node(int priority,int data)
  {
   this.data=data;
   this.priority=priority;
  }
}
class PriorityQueue
{
 Node front;
        
  BufferedReader br;

  void creation()
  {
   int a,b;
   boolean ch=true;
   Node newnode;
                   do
            {  
    try
    {

     System.out.print("enter the data for newnode : ");
     a=Integer.parseInt(br.readLine());
     System.out.println();
     System.out.print("enter the priority for new node : ");
     b= Integer.parseInt(br.readLine());
     System.out.println();
     newnode=new Node(b,a);
    if(front==null||newnode.priority<front.priority)
    {
     newnode.link=front;
     front=newnode;
    }
    else
    {
     Node temp=front;
     while(temp.link!=null&&newnode.priority>=temp.link.priority)
      temp=temp.link;
     newnode.link=temp.link;
     temp.link=newnode;
    }
     System.out.println("do u want to add one mode node [true/false] : ");

                          ch=Boolean.parseBoolean(br.readLine());
    }
               
    catch(Exception e)
    {
     System.out.println(e);
    }
  }
                    while(ch);
  }
             
   void display()
   {
   Node temp=front;
   if(temp==null)
    System.out.println("list is empty");
   else
   {

    while(temp!=null)
    {
     System.out.println(temp.priority+"--->"+temp.data);
     temp=temp.link;
    }
   }
  }

  void delete()
  {
   Node temp=front;

   if(temp==null)
    System.out.println("list is empty");
   else
   {
    System.out.println("deleted element is:" + front.data+" having a priority:"+front.priority);
    front=front.link;
    temp=null; /*whenever you are assining null to a reference of a class ,then the object associated  with  that reference is immediately deleted by the garbage collector due to automatic memory management */
    display();
   }
  }
  public static void main(String [] args)
  {
   int ch;
   PriorityQueue pq=new PriorityQueue();
   pq.br=new BufferedReader(new InputStreamReader(System.in));
  try
  {
   while(true)
   {
    System.out.println("1.creation");
    System.out.println("2.display");
    System.out.println("3.delete");
    System.out.println("4.exit");
    System.out.print("Enter your choice : ");
    ch=Integer.parseInt(pq.br.readLine());
    System.out.println();
    switch(ch)
    {
     case 1:
      pq.creation();
       break;
     case 2:
      pq.display();
       break;
     case 3:
      pq.delete();
       break;
     case 4:
      return;
     default:
      System.out.println("invalid choice...try again ");
    }
   }
  }
   catch(Exception e)
   {
    System.out.println(e);
   }
  }
}


2.Stack implementation using single linked list in c language

program:

#include<stdio.h>
#include<conio.h>
#include<alloc.h>
void display();
typedef struct stack
{
int ele;
stack *link;
} node;
node *top=NULL;
void push(int x)
{
node *current=NULL;
current=(node *)malloc(sizeof(node));
if(current==NULL)
{
printf("\nmemory is not allocated properly");
return;
}
current->ele=x;
current->link=top;
top=current;
}
void length()
{
node *temp;
int len=0;
temp=top;
while(temp!=NULL)
{
++len;
temp=temp->link;
}
printf("\n the length of the stack is : %d",len);
}
void pop()
{
node *temp;
if(top==NULL)
printf("\n stack is empty ");
else
{
temp=top;
top=top->link;
printf("\n the deleted element is :%d\n",temp->ele);
free(temp);
}
}
void topmost()
{
if(top==NULL)
printf("\nstack is empty");
else
printf("top most element is : %d",top->ele);
}
void display()
{
if(top==NULL)
printf("\n stack is empty ");
else
{
node *temp;
temp=top;
printf("\n the stack elements are:");
while(temp!=NULL)
{
printf("%d<---",temp->ele);
temp=temp->link;
}
}
}
void main()
{
int i,ch;
clrscr();
ab:
printf("\n1.push\n2.pop\n3.topmost\n4.display\n5.length of stack\n6.exit\nenter your choice:");
scanf("%d",&i);
switch(i)
{
case 1:
printf("\n enter the element that you want to insert into d stack :");
scanf("%d",&ch);
push(ch);
break;
case 2:
pop();
break;
case 3:
topmost();
break;
case 4:
display();
break;
case 5:
length();
break;
case 6:
return;
default:
printf("\n invalid choice...try again..");
}
goto ab;
}