/*
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*
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*/
package javaapplication4;
import java.io.IOException;
/**
*
*
@author dell
*/
public class Main
{
/**
* @param args the command line arguments
*/
public static void main(String args[]) throws IOException {
System.out.println("中国足球能否进入世界杯?");
System.out.println("是(y) 否(n) 不一定(p)");
char c = (char) System.in.read();
if (c == 'y') System.out.println("Cool");
else if (c == 'n')
System.out.println("Bad");
else if (c == 'p')
System.out.println("Sorry");
else
System.out.println("Input
Error");
}
}

import java.io.IOException;引入包。
char c = (char) System.in.read(); 输入字符串

System.in

Scanner sc = new Scanner(System.in);
String str =sc.nextLine();

谢谢。我试试。

我觉得最好是这样，因为是stdin，哈！
...
BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in))
...

String Username=in.next();