线程“main”中的异常 java.util.IllegalFormatConversionException: d != java.lang.String
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Exception in thread "main" java.util.IllegalFormatConversionException: d != java.lang.String
提问by elleninnit
I'm new to Java and I'm not sure how to fix the error I'm getting when trying to run this code:
我是 Java 新手，我不确定如何解决我在尝试运行此代码时遇到的错误：
import java.util.Scanner;
public class P3_3
{
public static void main(String[] args)
{
Scanner in = new Scanner(System.in);
System.out.print("Please enter a number: ");
int number = in.nextInt();
if (number < 0) number *= -1;
if (number >= 10 && number < 100)
{
number = 2;
}
else if (number >= 100 && number < 1000)
{
number = 3;
}
else if (number >= 1000 && number < 10000)
{
number = 4;
}
else if (number >= 10000 && number < 100000)
{
number = 5;
}
else if (number >= 100000 && number < 1000000)
{
number = 6;
}
else if (number >= 1000000 && number < 10000000)
{
number = 7;
}
else if (number >= 10000000 && number < 100000000)
{
number = 8;
}
else if (number >= 100000000 && number < 1000000000)
{
number = 9;
}
else
{
System.out.println("Number is greater than 10 billion.");
}
System.out.printf("%d has ", number + "digits.");
}
}
I'm trying to print how many digits the number has, by checking whether the number is >= 10, >= 100and so on...
I run the code and I'm able to input an int but once I input it and press enter all I get it an error and can't seem to see what I have done wrong. Can anyone enlighten me?
我正在尝试通过检查数字是否为>= 10, >= 100等来打印数字有多少位数......我运行代码并且我能够输入一个int但是一旦我输入它并按回车我就得到它一个错误，似乎看不出我做错了什么。任何人都可以启发我吗？
回答by Stefano Sanfilippo
The problem is here:
问题在这里：
System.out.printf("%d has ", number + "digits.");
the %dformat specifier requires an integer to be passed as second parameter to printf, but by concatenating numberand "digits.", you actually passed a String.
该%d格式说明需要作为第二个参数传递一个整数printf，而是通过连接number和"digits."，你居然通过了String。
Fixed version:
固定版本：
System.out.printf("has %d digits ", number);
note that you cannot print both the original number and the number of digits, because you overwrote one with the other in the numbervariable. Maybe use two different ones.
请注意，您不能同时打印原始数字和位数，因为您在number变量中用另一个覆盖了一个。也许使用两个不同的。
回答by dan
Like others have said, the issue was in the print statement. A better approach, instead of using all the if statements you should use the log10 method:
正如其他人所说，问题出在印刷声明中。一个更好的方法，而不是使用所有的 if 语句，您应该使用 log10 方法：
public static void main(String[] args){
Scanner in = new Scanner(System.in);
System.out.print("Please enter a number: ");
int number = in.nextInt();
if (number < 0) number *= -1;
System.out.printf("%d has %d digits\n", number, (int)Math.log10(number) + 1 );
}
回答by SMA
Change your last printf to:
将您的最后一个 printf 更改为：
System.out.printf("number has %d digits ", number);
Try to append all the string together and use specifier i.e.
尝试将所有字符串附加在一起并使用说明符即
System.out.printf("blah %d blah ", value).
