使用自己的方法将字符串从args数组转换为单个变量int

Question

我正在尝试一种方法，可以按照标题所述进行操作。 我想我已经完成了，但是由于某种原因，每次我尝试调用此方法时，都会收到错误消息。 我总是越界越好。 有人可以指出我的错误吗？ 我总是将数字发送到java ClassName之后的第二位。例如，如果我输入java ClassName 2568，则将args [1]发送到该方法。

public static int shiftHarder ( String commandLineInput )
{
    ArrayList <Character> commandLineString = new ArrayList <Character>();
    int counter;
    int number = 0;
    int ascii [] = new int [commandLineString.size()];
    int digits [] = new int [commandLineString.size()];

    for ( counter = 0; counter < commandLineInput.length(); counter++ )
    {
        commandLineString.add ( commandLineInput.charAt( counter ) ); 
    }

    for ( counter = 0; counter < commandLineString.size(); counter++ )
    {
        ascii [counter] = (int) commandLineString.get (counter);
    }

    if ( ascii [0] == 45 || ascii [0] == 43 )
    {
        for ( counter = 0; counter < ascii.length - 1; counter++ )
        {
            digits [counter] = ascii [counter + 1] -48;
        }

        if ( ascii [0] == 45)
        {
            for ( counter = 0; counter < digits.length; counter++ )
            {
                number = number*10;
                number = number + digits [counter];
            }
            number = - number; 
        }
        else
        {
            for ( counter = 0; counter < digits.length; counter++ )
            {
                number = number*10;
                number = number + digits [counter];
            }
        }           
    }

    else
    {
        for ( counter = 0; counter < ascii.length; counter++ )
        {
            digits [counter] = ascii [counter] -48;
        }

            for ( counter = 0; counter < digits.length; counter++ )
            {
                number = number*10;
                number = number + digits [counter];
            }
    }

    return number;
}

}

Answer 1

您正在初始化数组以使其大小为零，因为此时commandLineString为空：

int ascii [] = new int [commandLineString.size()];
int digits [] = new int [commandLineString.size()];

你可能是说

int ascii[] = new int[commandLineInput.length()];
int digits[] = new int[commandLineInput.length()];

否则，在填充commandLineString列表之后，将ascii[]和digits[]的声明移到