system.console NullPointerException [英] system.console NullPointerException

问题描述

我知道这是一个noobish错误，但我不知道如何解决它。

I know that this is a noobish error but I don't know how to fix it.

public static void main (String args[]){
Console kitty = System.console();
String username = kitty.readLine("Username: ");
}

String username = kitty.readLine ：）;

String username = kitty.readLine("Username: ");

会产生错误。有人可以告诉我我做错了什么，谢谢。

produces the error. Can someone please tell me what I am doing wrong, Thank you.

推荐答案

如果你想从标准输入读取用户名，您可以使用此代码：

If you want to read the username from the standard input, you could use this code:

try {
    System.out.print("Username: ");
    InputStreamReader streamReader = new InputStreamReader(System.in);
    BufferedReader bufferedReader = new BufferedReader(streamReader);
    String username = bufferedReader.readLine();
} catch (IOException e) {
    e.printStackTrace();
}

System.console（）返回的控制台不一定存在，为什么你得到一个NullPointerException。

The Console returned by System.console() does not necessarily exist, that is why you get a NullPointerException.

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