线性表（数组）实现栈Java

线性表（数组）实现栈-Java

package MyStack;

/**
 * 线性表实现
 * @param <AnyType>
 */
public class MyStackArray<AnyType> {
    
    
    public static final int DEFAULT_CAPACITY = 10;

    private int theSize;
    private AnyType[] theItem;

    public MyStackArray() {
    
    
        doClear();
    }

    public int size() {
    
    
        return theSize+1;
    }

    private void doClear() {
    
    
        theSize = -1;
        ensureCapacity(DEFAULT_CAPACITY);
    }

    public boolean isEmpty() {
    
    
        return size() == 0;
    }

    public void ensureCapacity(int newCapacity) {
    
    
        if (newCapacity < size()) return;

        AnyType[] old = theItem;
        theItem = (AnyType[]) new Object[newCapacity];
        for (int i = 0; i < size(); i++) {
    
    
            theItem[i] = old[i];
        }
    }

    public void push(AnyType newVal) {
    
    
        if (theItem.length == size()) {
    
    
            ensureCapacity(size()*2+1);
        }
        theSize++;
        theItem[theSize] = newVal;
    }

    public AnyType pop() {
    
    
        if (isEmpty()) {
    
    
            throw new IndexOutOfBoundsException("Empty");
        }
        AnyType item = theItem[theSize];
        theSize--;
        return item;
    }

    public AnyType top() {
    
    
        if (isEmpty()) {
    
    
            throw new IndexOutOfBoundsException("Empty");
        }
        return theItem[theSize];
    }

}

测试

package MyStack;

public class MyStackArrayTest {
    
    
    public static void main(String[] args) {
    
    
        MyStackArray<String> myStack = new MyStackArray<>();

        myStack.push("a");
        myStack.push("b");
        myStack.push("c");

        System.out.println(myStack.size());
        System.out.println(myStack.top());
        System.out.println(myStack.pop());
        System.out.println(myStack.top());
        System.out.println(myStack.pop());
        System.out.println(myStack.top());
        System.out.println(myStack.pop());
        System.out.println(myStack.top());
    }
}