Java 公共静态双方法？
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Public static double method?
提问by Azaria Gebo
import java.util.Scanner;
public class test {
private static int number1 = 100;
private static int number2 = 1;
public static double avgAge() {
return (number1 + number2) / 2;
}
public static void main(String[] args) {
System.out.println("Average number: " + test.avgAge());
}
}
Why does test.avgAge() = 50.0 instead of 50.5? Is there a way to output 50.5 instead?
为什么 test.avgAge() = 50.0 而不是 50.5？有没有办法输出 50.5 呢？
回答by CompuChip
The calculation is done as an integer calculation.
计算是作为整数计算完成的。
If you replace 2 by 2.0 you will get 50.5. I recommend adding a comment to that line to explain this to future readers. Alternatively you can explicitly cast to a double:
如果用 2.0 替换 2，您将得到 50.5。我建议在该行添加一条评论，向未来的读者解释这一点。或者，您可以显式转换为双精度：
((double) (number1 + number2)) / 2
回答by L Q
return ((double)(number1 + number2)) / 2;
回答by shankar
Just replace this function
只需更换此功能
import java.util.Scanner;
public class test {
private static int number1 = 100;
private static int number2 = 1;
public static double avgAge() {
return (number1 + number2) / 2.0;
}
public static void main(String[] args) {
System.out.println("Average number: " + test.avgAge()); //Average number: 50.5
}
}
回答by But I'm Not A Wrapper Class
It's because you're using intsthrough out the calculation before returning it as a double. Do the following:
这是因为您ints在将其作为double. 请执行下列操作：
private static double number1 = 100.0;
private static double number2 = 1.0;
Change these to double. Also, change the 2 to 2.0:
将这些更改为double. 另外，将 2 更改为 2.0：
return (number1 + number2) / 2.0;
Read more about intsand doubleshere:
了解更多关于ints与doubles在这里：
http://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html
http://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html
回答by coding_idiot
That's because of type promotion.
那是因为类型提升。
If in an operation, any of the operands is a double, then the result is promoted to double.
如果在一个操作中，任何一个操作数是双精度值，则结果被提升为双精度值。
Since here all operands are ints, the division results in an int.
由于这里所有操作数都是整数，因此除法结果为整数。
