Question

i am trying to use Console class in java. with this code

import java.io.Console;
public class ConsoleClass {
public static void main(String[] args){
    Console c=System.console();
    char[] pw;
    pw=c.readPassword("%s","pw :");
    for(char ch:pw){
        c.format("%c",ch);
    }
    c.format("\n");
    MyUtility mu =new MyUtility();
    while(true){
        String name=c.readLine("%s", "input?: ");
        c.format("output: %s \n",mu.doStuff(name));

    }

  } 
}
class MyUtility{
String doStuff(String arg1){
    return "result is " +arg1;
}
}

here i am getting NullPointerException when i tried to run in netbeans but i am not getting any Exception when tried to run in cmd with out netbeans IDE.Why?

Answer 1

Consoles are typically associated with processes that run independently of frameworks. They are a means of interfacing a process’s standard input and output with a shell. If your classes are running as a component of a larger framework, the framework may own the console, and your program might not have a console at all.

There are other conditions and techniques to launch a program without a console. They are typically used when the destruction of the console is guaranteed to occur, but you want the program detached in such a manner that the console’s destruction doesn’t signal the program’s termination.

As such, you cannot guarantee the existence of a console; but, if you are going to run your program in an environment where the console is likely to be present, you should take advantage of it.