我正在尝试创建一个程序（美国总统）。我想创建一个数组列表（总统编号，总统姓名，开始年份，去年）。
出于某种原因，我的构造函数无法正常工作，我不得不构建另一个方法，但是第二个方法导致StackOverFlowError（这是我第一次认为我是在使用此网站来提问，我认为我是来给定网站名称的正确位置）
这是我的代码：
import copy
def instantiate_mdl(dim_maxes, base=0):
""" Instantiate multi-dimensional list, that is a list of list of list ...
Arguments:
dim_maxes (list[int]): a list of dimension sizes, for example
[2, 4] represents a matrix (represented by lists) of 2 rows and
4 columns.
base (object): an optional argument indicating the object copies
of which will reside at the lowest level in the datastructure.
Returns:
base (list[base]): a multi-dimensional list of lists structure,
which is filled with clones of the base parameter.
"""
for dim_max in reversed(dim_maxes):
base = [copy.deepcopy(base) for i in range(dim_max)]
return base
data = instantiate_mdl([3, 5])
data[0][0] = 99999
data[1][1] = 88888
data[2][4] = 77777
for r in data:
print(r)
>>> # Output
>>> [99999, 0, 0, 0, 0]
>>> [0, 88888, 0, 0, 0]
>>> [0, 0, 0, 0, 77777]
答案 0 :(得分：4)
您在这里有一种方法：
public Presidents [] PresidentList ()
{
Presidents [] president = new Presidents [45];
president [0] = Presidents(1, "George Washington", 1789, 1797);
president [1] = Presidents(2, "John Adams", 1797, 1801);
president [2] = Presidents(3, "Thomas Jefferson", 1801, 1809);
president [3] = Presidents(4, "James Madison", 1809, 1817);
president [4] = Presidents(5, "James Monroe", 1817, 1825);
//...
return president;
}
但是每次致电：
president [...] = Presidents(...);
会打电话给
private Presidents Presidents(int i, String string, int j, int k) {
return Presidents (i, string, j, k);
}
哪个调用具有相同参数的相同方法，该方法将永远递归，从而导致堆栈溢出错误。
没有与该类称为同一个东西并返回某些东西的方法。这是为构造函数保留的。您已经有一个使用适当参数的构造函数，因此只需删除该方法即可：
private Presidents Presidents(int i, String string, int j, int k) {
return Presidents (i, string, j, k);
}
然后在您的方法中，需要添加new关键字：
president [0] = new Presidents(1, "George Washington", 1789, 1797);
^--- Here
答案 1 :(得分：1)
要在列表中的特定位置进行分配时，需要实例化新的President对象。
这里是您的方法：-
.includes-此处未实例化类private Presidents Presidents(int i, String string, int j, int k) {
//does not Instantiate a new object
return Presidents (i, string, j, k);
}
的新对象。它调用相同的Presidents方法，然后进行递归调用。
因此，这里您需要使用Presidents关键字实例化您的方法。
new它指向该类，构造函数将被调用。
答案 2 :(得分：1)
初始化数组时，应该创建Presidents类的新对象，因为该数组应该存储Presidents类型的对象。相反，您仅调用了该类的构造函数。而不是这样做：
if __name__ == "__main__":
try:
threads = [threading.Thread(name='daemon', target=daemon)
for _ in range(8)]
for th in threads:
th.daemon = True
th.start()
for th in threads:
while th.isAlive():
th.join(1)
except KeyboardInterrupt:
print('ctrl-c')
您应该这样做：
[Route("api/[controller]")]
[ApiController]
public class FilesController : Controller
{
private IFilesService _filesService { get; set; }
public FilesController(IFilesService filesService)
{
_filesService = filesService;
}
[HttpPost]
public async Task<IActionResult> UploadFile(IFormFile file)
{
var model = await _filesService.UploadFile(file);
return Ok();
}
}
对其余的数组索引也执行此操作。而这种方法：
president [0] = Presidents(1, "George Washington", 1789, 1797);
这是定义方法的错误方法。该方法不应与该类具有相同的名称。只有构造函数应该具有它。另外，如果您希望此方法返回Presidents类的对象，则return语句应如下所示：
president [0] = new Presidents(1, "George Washington", 1789, 1797);
但是该方法没有意义，因为您已经有 PresidentList（）方法返回数组。话虽这么说，最好将类内部的变量设为私有并定义getter方法来访问它们。无论如何，我已经对您的代码进行了一些修改，这应该可行：
private Presidents Presidents(int i, String string, int j, int k) {
return Presidents (i, string, j, k);
}
主要类别：
return Presidents (i, string, j, k);
我认为您正在尝试按所输入的数字打印所有总裁。如果没有，您可以在main方法中删除for循环。
答案 3 :(得分：0)
public class Presidents {
public int presidentNumber;
public String presidentName;
public int startingYear;
public int endingYear;
public Presidents(int PresidentNumber, String NameOfPresident, int StartingYear, int EndingYear)
{
this.presidentNumber = PresidentNumber;
this.presidentName = NameOfPresident;
this.startingYear = StartingYear;
this.endingYear = EndingYear;
}
public Presidents() {}
}
import java.util.Scanner;
import java.util.Random;
public class PresidentsQuiz {
public static void main (String [] args)
{
System.out.println("Do you know the 45 presidents of the United States? Enter a number between 1 and 45");
Scanner kb = new Scanner (System.in);
int input = kb.nextInt();
while (input < 1 || input > 45)
{
System.out.println("Enter a number between 1 and 45");
input = kb.nextInt();
}
Presidents [] president = new Presidents [45];
president [0] = new Presidents(1, "George Washington", 1789, 1797);
president [1] = new Presidents(2, "John Adams", 1797, 1801);
president [2] = new Presidents(3, "Thomas Jefferson", 1801, 1809);
president [3] = new Presidents(4, "James Madison", 1809, 1817);
president [4] = new Presidents(5, "James Monroe", 1817, 1825);
president [5] = new Presidents(6, "John Quincy Adams", 1825, 1829);
president [6] = new Presidents(7, "Andrew Jackson", 1829, 1837);
president [7] = new Presidents(8, "Martin Van Buren", 1837, 1841);
president [8] = new Presidents(9, "William Henry Harrison", 1841, 1841);
president [9] = new Presidents(10, "John Tyler", 1841, 1845);
president [10] = new Presidents(11, "James K. Polk", 1845, 1849);
president [11] = new Presidents(12, "Zachary Taylor", 1849, 1850);
president [12] = new Presidents(13, "Millard Fillmore", 1850, 1853);
president [13] = new Presidents(14, "Franklin Pierce", 1853, 1857);
president [14] = new Presidents(15, "James Buchanan", 1857, 1861);
president [15] = new Presidents(16, "Abraham Lincoln", 1861, 1865);
president [16] = new Presidents(17, "Andrew Johnson", 1865, 1869);
president [17] = new Presidents(18, "Ulysses S. Grant", 1869, 1877);
president [18] = new Presidents(19, "Rutherford B. Hayes", 1877, 1881);
president [19] = new Presidents(20, "James A. Garfield", 1881, 1881);
president [20] = new Presidents(21, "Chester A. Arthur", 1881, 1885);
president [21] = new Presidents(22, "Grover Cleveland", 1885, 1889);
president [22] = new Presidents(23, "Benjamin Harrison", 1889, 1893);
president [23] = new Presidents(24, "Grover Cleveland", 1893, 1897);
president [24] = new Presidents(25, "William McKinley", 1897, 1901);
president [25] = new Presidents(26, "Theodore Roosevelt", 1901, 1909);
president [26] = new Presidents(27, "William Howard Taft", 1909, 1913);
president [27] = new Presidents(28, "Woodrow Wilson", 1913, 1921);
president [28] = new Presidents(29, "Warren G. Harding", 1921, 1923);
president [29] = new Presidents(30, "Calvin Coolidge", 1923, 1929);
president [30] = new Presidents(31, "Herbert Hoover", 1929, 1933);
president [31] = new Presidents(32, "Franklin D. Roosevelt", 1933, 1945);
president [32] = new Presidents(33, "Harry S. Truman", 1945, 1953);
president [33] = new Presidents(34, "Dwight D. Eisenhower", 1953, 1961);
president [34] = new Presidents(35, "John F. Kennedy", 1961, 1963);
president [35] = new Presidents(36, "Lyndon B. Johnson", 1963, 1969);
president [36] = new Presidents(37, "Richard Nixon", 1969, 1974);
president [37] = new Presidents(38, "Gerald Ford", 1974, 1977);
president [38] = new Presidents(39, "Jimmy Carter", 1977, 1981);
president [39] = new Presidents(40, "Ronald Reagan", 1981, 1989);
president [40] = new Presidents(41, "George H. W. Bush", 1989, 1993);
president [41] = new Presidents(42, "Bill Clinton", 1993, 2001);
president [42] = new Presidents(43, "George W. Bush", 2001, 2009);
president [43] = new Presidents(44, "Barack Obama", 2009, 2017);
president [44] = new Presidents(45, "Donald Trump", 2017, 2018);
System.out.println(presidentList [0]);
kb.close();
}
}