我究竟做错了什么？Java IllegalFormatConversionException
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What am I doing wrong? Java IllegalFormatConversionException
提问by user2734475
I have some code for calculating properties of a circle:
我有一些用于计算圆属性的代码：
package circleinfo;
import java.util.Scanner;
public class Circleinfo {
public static void main(String[] args) {
Scanner input=new Scanner(System.in);
int r;
System.out.print("Enter the radius of the circle to find circumference, diameter, and area\n");
r = input.nextInt();
System.out.printf("The circumference is %f\n",(2*r*Math.PI));
System.out.printf("The diameter is %f\n",(r*2));
System.out.printf("The area is %f\n",(r*r*Math.PI));
}
}
It calculates circumference, but not the rest.
它计算周长，但不计算其余部分。
Enter the radius of the circle to find circumference, diameter, and area
10
The circumference is 62.831853
Exception in thread "main" java.util.IllegalFormatConversionException: f != java.lang.Integer
at java.util.Formatter$FormatSpecifier.failConversion(Formatter.java:4045)
at java.util.Formatter$FormatSpecifier.printFloat(Formatter.java:2761)
at java.util.Formatter$FormatSpecifier.print(Formatter.java:2708)
at java.util.Formatter.format(Formatter.java:2488)
at java.io.PrintStream.format(PrintStream.java:970)
at java.io.PrintStream.printf(PrintStream.java:871)
at circleinfo.Circleinfo.main(Circleinfo.java:30)
The diameter is Java Result: 1
采纳答案by arshajii
ris an int, so r*2is also an int, meaning that in your second print statement %fcannot be used. Try %dthere instead.
r是int，所以r*2也是int，这意味着在您的第二个打印语句%f中不能使用。去%d那里试试。
Recall that %fis for floating point numbers while %dis for integers. This is outlined in the documentation of Formatter(see Format String Syntax).
回答by Narendra Pathai
(r*2)will be an intand not a floatas ris intand 2is int. Use %dinstead
(r*2)will be anint和 not a floatas risint和2is int。使用%d替代
%c char Character
%d int Signed decimal integer.
%e, %E float Real number, scientific notation (lowercase or uppercase exponent marker)
%f float Real number, standard notation.
回答by Victor Fernández
This is because you had to put %dformat instead of %fin the result of the diameter
这是因为你必须把%d格式而不是%f直径的结果
import java.util.Scanner;
public class CircleInfo{
public static void main(String[] args){
Scanner input = new Scanner(System.in);
int radio;
System.out.print("Input radio: ");
radio = input.nextInt();
System.out.printf("%s%d%n","Diameter= ",(2*radio));
System.out.printf("%s%f%n","Area= ",(Math.PI*radio*radio));
System.out.printf("%s%f%n","Circumference = ",(2*Math.PI*radio));
}
}
