Read password from console without echoing characters. - Java Language Basics

Java examples for Language Basics:Console

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Description

Read password from console without echoing characters.

Demo Code

/*-// www  .  jav  a2  s.  c o m
 * Copyright (C) 2014 Erik Larsson
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
//package com.java2s;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

public class Main {
    /**
     * Read password from console without echoing characters.
     *
     * @return <code>null</code> if there is no console or end of stream is
     * reached when attempting to read password.
     */
    public static char[] readPassword() {
        try {
            final Method systemConsoleMethod = java.lang.System.class
                    .getMethod("console");
            final Object consoleObject = systemConsoleMethod.invoke(null);
            if (consoleObject == null) {
                /* No console. */
                return null;
            }

            final Class<? extends Object> consoleClass = Class
                    .forName("java.io.Console");
            final Method consoleReadPasswordMethod = consoleClass
                    .getMethod("readPassword");

            final Object passwordObject = consoleReadPasswordMethod
                    .invoke(consoleObject);
            if (passwordObject != null
                    && !(passwordObject instanceof char[])) {
                throw new RuntimeException("Unexpected type returned from "
                        + "java.io.Console.readPassword(): "
                        + passwordObject.getClass().getName());
            }

            return (char[]) passwordObject;
        } catch (ClassNotFoundException ex) {
            throw new RuntimeException(ex);
        } catch (NoSuchMethodException ex) {
            throw new RuntimeException(ex);
        } catch (IllegalAccessException ex) {
            throw new RuntimeException(ex);
        } catch (IllegalArgumentException ex) {
            throw new RuntimeException(ex);
        } catch (InvocationTargetException ex) {
            throw new RuntimeException(ex);
        }
    }
}

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