Merge pull request #832 from nuduja/master

Stack data Structure in Java Language added

Program's_Contributed_By_Contributors/Java_Programs/Misc/stackArray.java

@@ -0,0 +1,68 @@
+class stackjava {
+	public static void main(String[] args) {
+		StackX theStack = new StackX(10);  // create a stack with max size 10
+
+		theStack.push(30);  // insert given items
+		theStack.push(80);
+		theStack.push(100);
+		theStack.push(25);
+
+        //To peak the the last element pushed
+        System.out.println(theStack.peek());
+
+		while(!theStack.isEmpty()) {    // until it is empty, delete item from stack
+
+			double val = theStack.pop();
+			System.out.print(val);
+			System.out.print(" ");
+		}
+	}
+}
+
+//Implementation of Stack Class
+class StackX {
+
+   private int maxSize;    // size of stack array
+   private double[] stackArray;
+   private int top;           //top of the stack
+
+   public StackX(int s) {   // constructor
+
+    maxSize = s;       // set array size
+    stackArray = new double[maxSize];
+    top = -1;             // no items
+   }
+
+   public void push(double j) {
+
+	// check whether stack is full
+	    if (top == maxSize - 1)
+	      System.out.println("Stack is full");
+	    else
+	      stackArray[++top] = j;
+    }
+
+    public double pop() {
+        if (top == -1)
+            return -99;
+        else
+            return stackArray[top--];
+    }
+
+    public double peek() {
+        if (top == -1)
+            return -99;
+        else
+            return stackArray[top];
+    }
+
+    //Stack isEmpty method
+    public boolean isEmpty(){
+        return(top == -1);
+    }
+
+    //Stack isEmpty method
+    public boolean isFull(){
+        return (top == (maxSize -1));
+    }
+}