Consoleがnullの場合

//Sample21_01.java
import java.io.Console;

public class Sample21_01 {

   public static void main(String[] args) {
      Console cons = System.console();
      String str = null;

      if (cons != null) {
         str = cons.readLine("input: ");
      }
      System.out.println("echo : " + str);
   }
}