Java 来自System.in的BufferedReader输入尝试引发异常
我正在尝试使用BufferedReader从输入中读取a。它第一次工作,但第二次运行时,我得到一个异常Java 来自System.in的BufferedReader输入尝试引发异常,java,input,bufferedreader,inputstreamreader,Java,Input,Bufferedreader,Inputstreamreader,我正在尝试使用BufferedReader从输入中读取a。它第一次工作,但第二次运行时,我得到一个异常 john@fekete:~/devel/java/pricecalc$ java frontend.CUI > gsdfgd Invalid command! > I/O Error getting string: java.io.IOException: Stream closed I/O Error: java.io.IOException: java.io.IOExcep
john@fekete:~/devel/java/pricecalc$ java frontend.CUI
> gsdfgd
Invalid command!
> I/O Error getting string: java.io.IOException: Stream closed
I/O Error: java.io.IOException: java.io.IOException: Stream closed
> I/O Error getting string: java.io.IOException: Stream closed
I/O Error: java.io.IOException: java.io.IOException: Stream closed
> I/O Error getting string: java.io.IOException: Stream closed
它只是在循环中继续运行。我一定错过了什么
public static void main(String args[]) {
if (args.length == 0) {
while (!exit) {
try {
exit = processLine(commandLine());
} catch (IOException e) {
System.out.println("I/O Error: " + e);
}
}
System.out.println("Bye!");
} else if (args.length == 1) {
String line = new String(args[0]);
processLine(line);
} else {
String line = new String(args[0]);
for (String np : args) {
line = new String(line + " " + np);
}
processLine(line);
}
}
static private String commandLine() throws IOException {
String str = new String();
try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
System.out.print("> ");
str = new String(br.readLine());
str = str.trim();
} catch (IOException e) {
System.out.println("I/O Error getting string: "+ str + " " + e);
throw new IOException(e);
}
return str;
}
这一切似乎都与commandLine()不起作用有关,因此我仅将其和main包含在内。是的,您正在关闭此流:
try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in)))
try with resources语句将关闭块末尾的BufferedReader
,这将关闭InputStreamReader
,这将关闭系统
在这种情况下,您不想这样做,所以只需使用:
// Deliberately not closing System.in!
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
try {
...
}
尽管如此,这仍有可能不会像您所希望的那样运行,因为BufferedReader
可能会消耗(和缓冲)更多的数据。最好创建一次BufferedReader
(在调用代码中)并将其传递给方法
哦,我建议你扔掉这个:
String str = new String();
根本没有必要。这样会更好:
String str = "";
但即便如此,这也是一项毫无意义的任务。同样,您不需要从readLine()
返回的字符串中创建新字符串。只需使用:
return br.readLine().trim();
。。。在块中尝试。另外,在catch
块中记录str
没有意义,因为它将是空的-只有在读取行时才会抛出IOException
。退出定义在哪里?请发布一个可编译程序。@RohitJain其Java7@sanbhat. 它不可编译(在Java 7上)