Create arrayStack

docs/Stack/arrayStack.java

@@ -0,0 +1,133 @@
+package com.Fundamentals.Stack;
+
+import java.lang.*;
+
+/*define the manipulation of stack*/
+public interface arrayStack<T>
+{
+    int length();
+
+    T peek();//cat the element if the head of stack, whereas not remove it
+
+    int search(T t); //return the addr of obj in stack
+
+    boolean push(T data);
+
+    T pop();
+
+    boolean isEmpty();
+
+    void clear();
+}
+
+
+
+/*THE ARRAY OF STACK*/
+
+public class ImpArrayStac<T> implements arrayStack<T> {
+
+    private T[] t = (T[]) new Object[16]; //stack items
+    private int size = 0;//number of items
+
+    @Override
+    public int length() {
+        return size;
+    }
+
+    public void resize() {
+    //Move stack to a new array of size max.
+        T[] tmp = (T[]) new Object[t.length * 2];//can be insted of max
+        for (int i = 0; i < t.length; i++) {
+            tmp[i] = t[i];
+            t[i] = null;
+        }
+        t = tmp;
+        tmp = null;//便于gc处理，提高程序效率
+    }
+
+
+	/*查看栈顶元素，但是并不删除*/
+    @Override
+    public T peek() {
+        if (size == 0)
+            return null;
+        else {
+            return t[size - 1];
+        }
+    }
+
+    @Override
+    public int search(T t) {
+        for (int i = 0; i < size; i++)
+            if (t.equals(this.t[i]))
+                return i + 1;
+        return 0;
+    }
+
+    @Override
+    public void clear() {
+        for (int i = 0; i < t.length; i++)
+            t[i] = null;
+        size = 0;
+        //将其引用只为null，方便gc进行回收
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return size == 0;
+    }
+
+    @Override
+    public boolean push(T data) {
+        if (size >= t.length) {
+            resize();
+        }
+        //Add item to top of stack.
+        t[size++] = data;
+        return true;
+    }
+
+    @Override
+    //if (N > 0 && N == a.length/4) resize(a.length/2);
+    public T pop() {
+        if (size == 0)
+            return null;
+            // Avoid loitering
+        else
+            {
+                T tmp = t[size-1];
+                t[size-1] = null;
+                size--;
+                //Remove item from top of stack.
+                return tmp;
+            }
+
+    }
+
+    @Override
+    public String toString() {
+        StringBuilder sb = new StringBuilder();
+        sb.append("ArrayStack:\n[\n");
+        for (int i = size - 1; i >= 0; i--) {
+            sb.append(" " + t[i].toString());
+            if (i != size + 1) {
+                sb.append("\n");
+            }
+        }
+        sb.append("]");
+        return sb.toString();
+    }
+
+    public static void main(String[] args) {
+        com.Fundamentals.Stack.ImpArrayStac<String> arrayStack = new com.Fundamentals.Stack.ImpArrayStac<>();
+        arrayStack.push("Hello");
+        arrayStack.push("World");
+        arrayStack.push("00001");
+        arrayStack.push("00002");
+        arrayStack.pop();
+        arrayStack.peek();
+        arrayStack.pop();
+        System.out.println(arrayStack.toString());
+
+    }
+}