import java.util.*;
public class Queue{
int[] arr;
int top;
int begin;
public Queue(int size){
this.arr = new int[size];
this.top = -1;
this.begin = -1;
System.out.println("The Queue has created with the size:"+ size);
}
public boolean isFull(){
if(top == arr.length-1){
return true;
}else{
return false;
}
}
public boolean isEmpty(){
if (begin == -1 || begin == arr.length){
return true;
}else{
return false;
}
}
public void enq(int value){
if(isFull()){
System.out.println("The Queue is Full");
}
else if(isEmpty()){
begin = 0;
top++;
arr[top] = value;
System.out.println(value+" is successfully inserted.");
}
else{
top++;
arr[top] = value;
System.out.println(value+ " is successfully inserted");
}
}
public static void main(String[] args){
Queue q = new Queue(5);
q.enq(1);
q.enq(2);
q.enq(3);
q.enq(4);
q.enq(5);
}
}
with help arrays shape and structure create a full video of the line by line execution of the full code as per the Java developer kit
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This Java code implements a Queue data structure using an array. The Queue class has three main instance variables: arr which is the integer array to store elements, top which points to the last inserted element, and begin which points to the first element. The constructor initializes the queue with a given size, setting both top and begin to -1. The class includes helper methods isFull and isEmpty to check queue status, and an enq method to add elements. In the main method, we create a queue of size 5 and insert values 1 through 5.
Let's trace through the Queue constructor execution step by step. When we call new Queue with size 5, the constructor begins execution. First, it creates an integer array of size 5 with all elements initialized to 0. Then it sets the top pointer to -1, indicating no elements have been added yet. Next, it sets the begin pointer to -1, showing the queue is empty. Finally, it prints a confirmation message to the console. After constructor completion, we have an empty queue ready for operations.
Now let's trace the first enqueue operation. When we call enq with value 1, the method first checks if the queue is full by comparing top with array length minus 1. Since top is -1 and not equal to 4, the queue is not full. Next, it checks if the queue is empty by testing if begin equals -1 or begin equals array length. Since begin is -1, the queue is empty, so we enter the isEmpty block. First, begin is set to 0, pointing to the first position. Then top is incremented from -1 to 0. The value 1 is stored at arr[0]. Finally, a success message is printed to the console.
Let's analyze a Java Queue implementation step by step. This Queue class uses an array to store elements, with two important pointers: 'begin' which points to the first element, and 'top' which points to the last inserted element. We'll trace through the execution of enqueue operations to understand how the queue works.
First, let's examine the constructor execution. When we create a new Queue with size 5, the constructor initializes an integer array of size 5, sets both top and begin pointers to -1, and prints a creation message. The initial state shows an empty queue with all array elements initialized to 0, and both pointers set to -1 indicating the queue is empty.
Before we start enqueuing elements, let's understand the helper methods. The isFull method checks if the top pointer equals the array length minus 1, which would be 4 in our case. The isEmpty method checks if begin equals -1, meaning we never started, or if begin equals the array length, meaning all elements have been consumed. Currently, isFull returns false since top is -1, and isEmpty returns true since begin is -1.
Now let's trace the first enqueue operation step by step. When enq(1) is called, we first check if the queue is full - since top is -1, it's not full. Then we check if it's empty - since begin is -1, it is empty. We enter the isEmpty block, set begin to 0, increment top to 0, store 1 at arr[0], and print a success message. Now we have our first element in the queue!
Now let's see the remaining enqueue operations. For enq(2), since the queue is no longer empty, we skip the isEmpty block and go to the else block. We increment top to 1 and store 2 at arr[1]. Similarly for enq(3), top becomes 2 and we store 3 at arr[2]. For enq(4), top becomes 3 and we store 4 at arr[3]. Finally for enq(5), top becomes 4 and we store 5 at arr[4]. Now our queue is completely full with all five elements stored sequentially. The begin pointer remains at 0 throughout, pointing to the first element, while top has moved to 4, pointing to the last inserted element.