Using arrays in Java to implement stack data structure instances _java

The stack is one of the most important data structures in the Java language, and its implementation should at least include the following methods:

1.pop () out stack operation, pop-up stack top element.
2.push (e e) stack operation
3.peek () View top of Stack element
4.isEmpty () stack is empty

In addition, to implement a stack, you should also consider several issues:

1. The initial size of the stack and how to add stack space after the stack is full
2. Update the stack needs to be synchronized

For a simple example, use an array to implement the stack with the following code:

Copy Code code as follows:

public class Stack<e> {

Java does not support generic arrays, if needed, use Java-provided containers
Private object[] Stack;

Default initial size of stack
private static final int init_size = 2;

Stack Top Index
private int index;

    public Stack () { 
        stack = new Object[init_ size]; 
        index = -1; 
   } 

   /** 
     * Construction method  
     *  
     * @param initsize 
     *      Initial size of        stack  
     */
    Public Stack (int initsize) { 
        if (initsize < 0) { 
   ;          throw new IllegalArgumentException (); 
        } 
        stack = new object[ initsize]; 
        index = -1; 
   } 

/**
* Out Stack operation
*
* @return Stack Top Object
*/
Public synchronized E Pop () {
if (!isempty ()) {
E temp = peek ();
stack[index--] = null;
return temp;
}
return null;
}

/**
* Into stack operation
*
* @param obj
* Waiting for the object to stack
*/
Public synchronized void push (E obj) {
if (Isfull ()) {
object[] temp = stack;
If the stack is full, create a stack with twice times the current stack space
stack = new object[2 * Stack.length];
System.arraycopy (temp, 0, stack, 0, temp.length);
}
Stack[++index] = obj;
}

/**
* View the top of the Stack object
*
* @return Stack Top Object
*/
Public E Peek () {
if (!isempty ()) {
Return (E) Stack[index];
}
return null;
}

/**
* See if the stack is empty
*
* @return Returns True if the stack is null or FALSE
*/
public Boolean IsEmpty () {
return index = = 1;
}

/**
* See if the stack is full
*
* @return returns False if the stack returns true if it is full
*/
public Boolean isfull () {
return index >= stack.length-1;
}
}

Finally, the Java implementation of the Stack (java.util.Stack) of the data structure, it is implemented by inheriting vector classes, in general, we use directly to the line.