Java版 - 刚刚开始学习java，麻烦帮我看一下我哪里错了行吗？谢谢 |
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s*******9
发帖数: 1 | 1 public class GetInputFromKeyboard1 {
public static void main(String[] args){
BufferedReader dataIn = new BufferedReader(new InputStreamReader(
System.in));
BufferedReader is = new BufferedReader(new InputStreamReader(System.
in));
int number ;
System.out.println("How Many Names You Wish To Enter:");
String name = "";
String strIn = "";
try{
strIn = is.readLine();
}catch(IOException e){
System.out.println( | Z****e
发帖数: 2999 | 2 when you define "number", no initial value is assigned
then you wrap the assignment to "number" by parseInt in a try block, but in
the catch block, you just printed an error message without ending the
program
so when a NumberFormatException happens, the control flow will still
continue to the for loop, but at this point, no value has been assigned to "
number" yet
the compiler sees this potential problem, would not let it pass compilation
solution: assign initial value 0, or return at the end of
【在 s*******9 的大作中提到】
: public class GetInputFromKeyboard1 {
: public static void main(String[] args){
: BufferedReader dataIn = new BufferedReader(new InputStreamReader(
: System.in));
: BufferedReader is = new BufferedReader(new InputStreamReader(System.
: in));
: int number ;
: System.out.println("How Many Names You Wish To Enter:");
: String name = "";
: String strIn = "";
| c****7
发帖数: 13 | 3 In java, for local variable, you need to initialize it first before you use
it. Since you initialize it in the try{} block, it may not be initialized
because of exception is thrown out. Compiler will complain it. | m******t
发帖数: 2416 | 4 I have always hated it when the compiler does this. The JLS specifically
says
a variable is always assigned a default value when it's created. Well, if
it's
assigned a default value, then it's in a known state, and you can't say it's
not initialized, right?
I think it should've been a lint warning instead of a hard error.
in
"
compilation
,
【在 Z****e 的大作中提到】
: when you define "number", no initial value is assigned
: then you wrap the assignment to "number" by parseInt in a try block, but in
: the catch block, you just printed an error message without ending the
: program
: so when a NumberFormatException happens, the control flow will still
: continue to the for loop, but at this point, no value has been assigned to "
: number" yet
: the compiler sees this potential problem, would not let it pass compilation
: solution: assign initial value 0, or return at the end of
| c*****t
发帖数: 1879 | 5 It doesn't matter that much in most cases though, since good code should
have 0 warning and 0 errors anyways.
's
【在 m******t 的大作中提到】
: I have always hated it when the compiler does this. The JLS specifically
: says
: a variable is always assigned a default value when it's created. Well, if
: it's
: assigned a default value, then it's in a known state, and you can't say it's
: not initialized, right?
: I think it should've been a lint warning instead of a hard error.
:
: in
: "
| m******t
发帖数: 2416 | 6
Well just because a good driver should have no tickets on record
doesn't mean a cop can put me in jail for a night just for not wearing
the safety belt! ;-)
【在 c*****t 的大作中提到】
: It doesn't matter that much in most cases though, since good code should
: have 0 warning and 0 errors anyways.
:
: 's
| s******e
发帖数: 493 | 7 Last time(a couple of years ago) I checked, no local primitive variable
should be assigned a default value by compiler. Did this change since then? |
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