java - Netbeans 抛出 NumberFormatException

Question

Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: For input string: "1.0" at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48) at java.lang.Integer.parseInt(Integer.java:458) at java.lang.Integer.parseInt(Integer.java:499) at newform.fivth.(fivth.java:150) at newform.fivth$3.run(fivth.java:623) at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209) at java.awt.EventQueue.dispatchEvent(EventQueue.java:597) at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269) at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184) at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161) at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

这是错误所指的代码部分:

while (results4.next())
{
for(int i=1;i<=12;i++)
            {
         x.add(Integer.parseInt(results4.getString(i))+0.5);       

            }  

}
}
catch(SQLException sqlEx){
System.out.println(
"* Error retrieving data! *");
sqlEx.printStackTrace();
System.exit(1);
} 

Answer 1

根据Java，字符串“1.0”不能表示为int，但可以表示为double。 Integer.parseInt 的解析逻辑期望不有小数点，即使小数点后面只有一个零。

引用Javadoc for Integer.parseInt

Parses the string argument as a signed decimal integer. The characters in the string must all be decimal digits, except that the first character may be an ASCII minus sign '-' ('\u002D') to indicate a negative value or an ASCII plus sign '+' ('\u002B') to indicate a positive value.

它不需要小数点。

如果您必须接受 String 例如 "1.0" 并存储结果 int，那么我会将其解析为 Double 然后调用 intValue。而不是以下内容:

Integer.parseInt(results4.getString(i))

我会用这个:

Double.valueOf(results4.getString(i)).intValue()

当然，您必须使该值确实是一个整数。请参阅this SO question了解这些详细信息。