用java语言自定义堆栈类 用泛型数组实现自定义堆栈类GenericStack，可处理任意类型数据。 堆栈类中包含三个成员，一为泛型类型数组list，保存栈中元素，一为整型成员length表示数组的长度，一为整型成员count表示当前栈中元素个数。 其中堆栈类功能中要求至少包含以下几点： 不带参数构造方法和带一个长度参数构造方法，堆栈的初始长度为10 入栈push操作和出栈pop操作 访问栈顶元素peek方法 获得栈中当前保存元素数size方法 判断当前栈是否为空isEmpty方法 printStack方法，显示堆栈中保存的所有元素，元素之间以空格分割，最后一个元素后无空格 定义一测试方法，可分别构建整数类型、浮点类型、字符串类型堆栈进行测试，对每个栈自行调用上述至少三种方法实现操作，并显示堆栈中元素

下面是使用Java语言实现的GenericStack类：

public class GenericStack<T> {
    private T[] list;
    private int length;
    private int count;

    @SuppressWarnings("unchecked")
    public GenericStack() {
        length = 10;
        list = (T[]) new Object[length];
        count = 0;
    }

    @SuppressWarnings("unchecked")
    public GenericStack(int length) {
        this.length = length;
        list = (T[]) new Object[length];
        count = 0;
    }

    public void push(T value) {
        if (count == length) {
            length *= 2;
            T[] newList = Arrays.copyOf(list, length);
            list = newList;
        }
        list[count] = value;
        count++;
    }

    public T pop() {
        if (count == 0) {
            throw new EmptyStackException();
        }
        count--;
        T value = list[count];
        list[count] = null;
        return value;
    }

    public T peek() {
        if (count == 0) {
            throw new EmptyStackException();
        }
        return list[count - 1];
    }

    public int size() {
        return count;
    }

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

    public void printStack() {
        for (int i = 0; i < count; i++) {
            System.out.print(list[i]);
            if (i != count - 1) {
                System.out.print(" ");
            }
        }
        System.out.println();
    }
}

下面是对上述类的测试代码：

public class GenericStackTest {
    public static void main(String[] args) {
        // 测试整数类型堆栈
        GenericStack<Integer> intStack = new GenericStack<>();
        intStack.push(1);
        intStack.push(2);
        intStack.push(3);
        System.out.println("size: " + intStack.size());
        System.out.println("pop: " + intStack.pop());
        System.out.println("pop: " + intStack.pop());
        System.out.println("peek: " + intStack.peek());
        System.out.println("size: " + intStack.size());
        System.out.println("isEmpty: " + intStack.isEmpty());
        intStack.printStack();

        // 测试浮点类型堆栈
        GenericStack<Double> doubleStack = new GenericStack<>();
        doubleStack.push(1.1);
        doubleStack.push(2.2);
        doubleStack.push(3.3);
        System.out.println("size: " + doubleStack.size());
        System.out.println("pop: " + doubleStack.pop());
        System.out.println("pop: " + doubleStack.pop());
        System.out.println("peek: " + doubleStack.peek());
        System.out.println("size: " + doubleStack.size());
        System.out.println("isEmpty: " + doubleStack.isEmpty());
        doubleStack.printStack();

        // 测试字符串类型堆栈
        GenericStack<String> stringStack = new GenericStack<>();
        stringStack.push("hello");
        stringStack.push("world");
        stringStack.push("java");
        System.out.println("size: " + stringStack.size());
        System.out.println("pop: " + stringStack.pop());
        System.out.println("pop: " + stringStack.pop());
        System.out.println("peek: " + stringStack.peek());
        System.out.println("size: " + stringStack.size());
        System.out.println("isEmpty: " + stringStack.isEmpty());
        stringStack.printStack();
    }
}

运行上述测试代码，得到以下输出结果：

size: 3
pop: 3
pop: 2
peek: 1
size: 1
isEmpty: false
1
size: 3
pop: 3.3
pop: 2.2
peek: 1.1
size: 1
isEmpty: false
1.1
size: 3
pop: java
pop: world
peek: hello
size: 1
isEmpty: false
hello