[英]How to get Java to wait for user Input
I am trying to make an IRC bot for my channel. 我正在尝试为我的频道制作一个IRC机器人。 I would like the bot to be able to take commands from the console.
我希望机器人能够从控制台获取命令。 In an attempt to make the main loop wait for the user to input something I added the loop:
为了使主循环等待用户输入我添加循环的东西:
while(!userInput.hasNext());
this did not seem to work. 这似乎不起作用。 I have heard of BufferedReader but I have never used it and am not sure if this would be able to solve my problem.
我听说过BufferedReader,但我从未使用它,也不确定这是否能够解决我的问题。
while(true) {
System.out.println("Ready for a new command sir.");
Scanner userInput = new Scanner(System.in);
while(!userInput.hasNext());
String input = "";
if (userInput.hasNext()) input = userInput.nextLine();
System.out.println("input is '" + input + "'");
if (!input.equals("")) {
//main code
}
userInput.close();
Thread.sleep(1000);
}
There is no need for you to check for available input waiting and sleeping until there is since Scanner.nextLine()
will block until a line is available. 您无需检查可用的输入等待和休眠,直到
Scanner.nextLine()
将阻塞,直到有一条线可用。
Have a look at this example I wrote to demonstrate it: 看看我写的这个例子来演示它:
public class ScannerTest {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
try {
while (true) {
System.out.println("Please input a line");
long then = System.currentTimeMillis();
String line = scanner.nextLine();
long now = System.currentTimeMillis();
System.out.printf("Waited %.3fs for user input%n", (now - then) / 1000d);
System.out.printf("User input was: %s%n", line);
}
} catch(IllegalStateException | NoSuchElementException e) {
// System.in has been closed
System.out.println("System.in was closed; exiting");
}
}
}
Please input a line
请输入一行
hello你好
Waited 1.892s for user input用户输入等待1.892秒
User input was: hello用户输入是:你好
Please input a line请输入一行
^D^ d
System.in was closed;System.in已关闭; exiting
退出
So all you have to do is to use Scanner.nextLine()
and your app will wait until the user has entered a newline. 因此,您所要做的就是使用
Scanner.nextLine()
,您的应用将等到用户输入换行符。 You also don't want to define your Scanner inside the loop and close it since you're going to use it again in the next iteration: 你也不想在循环中定义你的扫描仪并关闭它,因为你将在下一次迭代中再次使用它:
Scanner userInput = new Scanner(System.in);
while(true) {
System.out.println("Ready for a new command sir.");
String input = userInput.nextLine();
System.out.println("input is '" + input + "'");
if (!input.isEmpty()) {
// Handle input
}
}
}
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