Java Tutorial/Development/Console Read
Содержание
Getting Data From the Keyboard
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.StreamTokenizer;
public class MainClass {
public static void main(String[] av) throws IOException {
StreamTokenizer tf = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
String s = null;
int i;
while ((i = tf.nextToken()) != StreamTokenizer.TT_EOF) {
switch (i) {
case StreamTokenizer.TT_EOF:
System.out.println("End of file");
break;
case StreamTokenizer.TT_EOL:
System.out.println("End of line");
break;
case StreamTokenizer.TT_NUMBER:
System.out.println("Number " + tf.nval);
break;
case StreamTokenizer.TT_WORD:
System.out.println("Word, length " + tf.sval.length() + "->" + tf.sval);
break;
default:
System.out.println("What is it? i = " + i);
}
}
}
}
How to read from standard input
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
public class MainClass {
public static void main(String[] args) throws IOException {
BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
String s;
while ((s = in.readLine()) != null && s.length() != 0)
System.out.println(s);
// An empty line or Ctrl-Z terminates the program
}
}
Read from keyboard
import java.io.IOException;
public class MainClass {
public static void main(String[] args) {
try {
while (true) {
int datum = System.in.read();
if (datum == -1)
break;
System.out.println(datum);
}
} catch (IOException ex) {
System.err.println("Couldn"t read from System.in!");
}
}
}
Read password from console
/*
* Copyright (c) 1995 - 2008 Sun Microsystems, Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* - Neither the name of Sun Microsystems nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
import java.io.Console;
import java.io.IOException;
import java.util.Arrays;
public class Password {
public static void main(String args[]) throws IOException {
Console c = System.console();
if (c == null) {
System.err.println("No console.");
System.exit(1);
}
String login = c.readLine("Enter your login: ");
char[] oldPassword = c.readPassword("Enter your old password: ");
if (verify(login, oldPassword)) {
boolean noMatch;
do {
char[] newPassword1 = c.readPassword("Enter your new password: ");
char[] newPassword2 = c.readPassword("Enter new password again: ");
noMatch = !Arrays.equals(newPassword1, newPassword2);
if (noMatch) {
c.format("Passwords don"t match. Try again.%n");
} else {
change(login, newPassword1);
c.format("Password for %s changed.%n", login);
}
Arrays.fill(newPassword1, " ");
Arrays.fill(newPassword2, " ");
} while (noMatch);
}
Arrays.fill(oldPassword, " ");
}
// Dummy verify method.
static boolean verify(String login, char[] password) {
return true;
}
// Dummy change method.
static void change(String login, char[] password) {
}
}
Tokenizing a Stream from console input
A StreamTokenizer object can recognize the following kinds of tokens:
- Numbers:
- Strings:
- Words:
- Comments:
- Whitespace
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.StreamTokenizer;
public class MainClass {
public static void main(String[] av) throws IOException {
StreamTokenizer tf = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
String s = null;
int i;
while ((i = tf.nextToken()) != StreamTokenizer.TT_EOF) {
switch (i) {
case StreamTokenizer.TT_EOF:
System.out.println("End of file");
break;
case StreamTokenizer.TT_EOL:
System.out.println("End of line");
break;
case StreamTokenizer.TT_NUMBER:
System.out.println("Number " + tf.nval);
break;
case StreamTokenizer.TT_WORD:
System.out.println("Word, length " + tf.sval.length() + "->" + tf.sval);
break;
default:
System.out.println("What is it? i = " + i);
}
}
}
}