个人算法小题小结

//两个栈实现队列功能
public class TestALL {
    public Stack<Integer> firstStack;
    public Stack<Integer> secondStack;
    public TestALL(){
        firstStack=new Stack<Integer>();
        secondStack=new Stack<Integer>();

    }
    public void add(int scannerInt){
        firstStack.push(scannerInt);
    }
    public int poll(){
        if(firstStack.isEmpty()&&secondStack.isEmpty()){
            throw new RuntimeException("栈为空");
        }else if(secondStack.isEmpty()){
            while(!firstStack.isEmpty()){
                secondStack.push(firstStack.pop());
            }
        }
        return secondStack.pop();
    }
    public int peek(){
        if(firstStack.isEmpty()&&secondStack.isEmpty()){
            throw new RuntimeException("栈为空");
        }else if(secondStack.isEmpty()){
            while(!firstStack.isEmpty()){
                secondStack.push(firstStack.pop());
            }
        }
        return secondStack.peek();
    }
}