数组实现栈Java

痛定思痛。 2023-07-11 08:48 35阅读 0赞

每次入栈之前先判断栈的容量是否够用，如果不够用就用`Arrays.copyOf()`进行扩容；

public class MyStack {
        private int[] storage;//存放栈中元素的数组
        private int capacity;//栈的容量
        private int count;//栈中元素数量
        private static final int GROW_FACTOR = 2;
    
        //TODO：不带初始容量的构造方法。默认容量为8
        public MyStack() {
            this.capacity = 8;
            this.storage=new int[8];
            this.count = 0;
        }
    
        //TODO：带初始容量的构造方法
        public MyStack(int initialCapacity) {
            if (initialCapacity < 1)
                throw new IllegalArgumentException("Capacity too small.");
    
            this.capacity = initialCapacity;
            this.storage = new int[initialCapacity];
            this.count = 0;
        }
    
        //TODO：入栈
        public void push(int value) {
            if (count == capacity) {
                ensureCapacity();
            }
            storage[count++] = value;
        }
    
        //TODO：确保容量大小
        private void ensureCapacity() {
            int newCapacity = capacity * GROW_FACTOR;
            storage = Arrays.copyOf(storage, newCapacity);
            capacity = newCapacity;
        }
    
        //TODO：返回栈顶元素并出栈
        private int pop() {
            if (count == -1)
                throw new IllegalArgumentException("Stack is empty.");
            count--;
            return storage[count];
        }
    
        //TODO：返回栈顶元素不出栈
        private int peek() {
            if (count == 0){
                throw new IllegalArgumentException("Stack is empty.");
            }else {
                return storage[count-1];
            }
        }
    
        //TODO：判断栈是否为空
        private boolean isEmpty() {
            return count == 0;
        }
    
        //TODO：返回栈中元素的个数
        private int size() {
            return count;
        }
    
    }

摘自：[https://github.com/Snailclimb/JavaGuide/blob/master/docs/java/Java%E7%A8%8B%E5%BA%8F%E8%AE%BE%E8%AE%A1%E9%A2%98.md][https_github.com_Snailclimb_JavaGuide_blob_master_docs_java_Java_E7_A8_8B_E5_BA_8F_E8_AE_BE_E8_AE_A1_E9_A2_98.md]

[https_github.com_Snailclimb_JavaGuide_blob_master_docs_java_Java_E7_A8_8B_E5_BA_8F_E8_AE_BE_E8_AE_A1_E9_A2_98.md]: https://github.com/Snailclimb/JavaGuide/blob/master/docs/java/Java%E7%A8%8B%E5%BA%8F%E8%AE%BE%E8%AE%A1%E9%A2%98.md