堆栈返回对象而不是整数 [英] Stack returning Objects instead of Integers
问题描述
我正在尝试实现一个涉及堆栈数组的程序.每个堆栈都接受 Integer 对象,但问题是当我尝试从堆栈中获取 Integer 对象时:
I'm trying to implement a program that involves an array of stacks. Each stack takes in Integer objects, but the problem is when I try to get an Integer object from the stack:
import java.util.*;
public class Blocks
{
public static void main(String[] args)
{
System.out.println();
Scanner input = new Scanner(System.in);
Stack[] blocks = new Stack[input.nextInt()];
for (int i = 0; i < blocks.length; i++) {blocks[i] = new Stack<Integer>();} //initializing main array of stacks of blocks
for (int i = 0; i < blocks.length; i++) {blocks[i].push(i);} //add first block to each stack
Stack retainer = new Stack<Integer>(); //used for when moving stacks of blocks instead of one block.
boolean m; //move or pile
boolean on; //onto or over
int fromBlock; //block being moved
int toBlock; //block where the fromBlock is being moved
String command = input.next();
while (!command.equals("quit"))
{
m = command.equals("move");
fromBlock = input.nextInt();
on = input.next().equals("onto");
toBlock = input.nextInt();
if (m) //put back blocks on fromBlock
{
if (on) //put back blocks on toBlock
{
int holder = blocks[fromBlock].pop().intValue(); //I get a compiler error here
moveOnto(blocks, holder, toBlock);
}
else //fromBlock goes on top of stack on toBlock
{
}
}
else //bring blocks on fromBlock
{
if (on) //put back blocks on toBlock
{
}
else //fromBlock goes on top of stack on toBlock
{
}
}
command = input.next();
}
}
void moveOnto(Stack[] array, int sBlock, int rBlock)
{
}
}
错误表明无法识别 .intValue().显然,这是 Integer 的一个方法,从那时我发现它返回的是 Object 对象而不是 Integer 类型.我怎样才能让它返回整数类型?
The error says that is doesn't recognize .intValue(). Obviously that is a method of Integer, and I found out from that point that it's returning Object objects instead of Integer types. How can I make it return Integer types?
推荐答案
(哎呀 - Java 不允许泛型数组)更改您的 Stack
变量声明以使用 Stack
的通用版本:
(oops - Java doesn't allow arrays of generics)
Change your Stack
variable declaration to use the generic version of Stack
:
Stack<Integer>[] blocks = new Stack<Integer>[input.nextInt()];
否则,当您访问非通用堆栈的 .pop()
方法时,它只会返回一个对象,您需要将其转换回整数 为了访问 Integer 方法,例如intValue():
Otherwise when you access the non-generic stack's .pop()
method it just returns an Object which you would need to cast back to an Integer In order to access Integer methods like intValue():
int holder = ((Integer)blocks[fromBlock].pop()).intValue();
(但如果您修复了声明,则不需要强制转换.)
(But you won't need to cast if you fix the declarations.)
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