Develop Reference

Java all methods work for a string except returning the string

for some reason, I can do just about any method for a string. This includes:
*Getting the length of the string
*Adding to the string
*Using substring
*And probably everythng else
Except, I cant get the value of the string except when using my drawString method to draw to the screen in lwjgl. Here is my code before i further explain the problem.
public static boolean chatOn = false;
public static String text = "";
public static float typetimer = 0;
public static int ctrltimer = 0;
public static boolean runcmd = false;
public static void chat() {
if (Keyboard.isKeyDown(Keyboard.KEY_TAB)) {
if (ctrltimer < 0) {
chatOn = !chatOn;
Keyboard.destroy();
try {Keyboard.create();} catch (LWJGLException e) {}
ctrltimer = 10;
}
}
ctrltimer -= Game.delta;
typetimer -= Game.delta;
if (chatOn) {
//try {text.replace(null, "happy");} catch(NullPointerException e) {}
System.out.println(text);//print to console, dosen't
Text.drawString(text, 0, 0);//write the text on the screen with my draw method, does work
System.out.println(text);//print to console, dosen't, yet the one drawstring worked
if (typetimer < 0) {
while (Keyboard.next()) {
try {
if (Keyboard.getEventKey() == Keyboard.KEY_BACK) {
text = text.substring(0, text.length()-1);
typetimer = 1;
System.out.println(text);//print to console, doesn't
}
else if (Keyboard.getEventKey() == Keyboard.KEY_RETURN) {
System.out.println(text);//print to console, doesn't
runCommand();
text = "";
chatOn = false;
}
else {
System.out.println(text);//print to console, doesn't
text = text + Keyboard.getEventCharacter();
}
typetimer = 10;
} catch(Exception e){
}
}
}
}
}
public static void runCommand() {
String command = text;
System.out.println(command);//print to console, doesnt
if (command.startsWith("time")) {
try {
String[] time = new String[1];
time = command.split(" ", 0);
Camera.nighttimeASecond = Integer.parseInt(time[0]);
} catch (Exception e){
System.out.println("could not set time");
}
}
}
If you read my notes inside the code you can see where I have put print methods and drawString method. The print methods print nothing and sometimes might print the first few words of the string, although the drawString method worked fine. Thanks - Tyler

If System.out.println(text); is empty before Text.drawString(text, 0, 0); is called, then text should be empty when Text.drawString() is called. You should follow mattias' suggested debugging guide and find out where your issue is occuring (or add some System.out.println()s following text through your code and tracing it if you're particularly lazy :p). Without having a look at your Text class, I'd be willing to bet that the string to be printed is never getting set, and Text is printing a static string, or that the string to be printed is getting changed by the Text class itself.
Judging by:
String command = text;
System.out.println(command);//print to console, doesnt
text is never getting set.

Java - <identifier> expecter error

I was writing a java tool that toggles wether a game mod is active (specifically, the game is Dwarf Fortress, and the mod is DFHack) and the program is nearly done. However, I cant seem to get the variables right that tell the program how to check if the mod is active or not.
I got this status file containing a single character, being 1 for active and 0 for inactive.
This is the code (By the way, if it is needed: I checked the name of the file and it matches the class declaration).
package nl.dirkkok.dfhacktoggle;
/*
* DFHacktoggle
* 28-12-2013 # 2:02 PM
*
* This program will disable DFHack if it is enabled, and enable it if it is disabled.
*
* Using this tool is at your own risk. If you send me an email complaining about this program doing anything you dont want, then I will laugh at you, and tell you that you cant read. :)
*
* Created by Dirk Kok <d.kok.2000#gmail.com>. This tool is my property, but I do not claim rights of neither Dwarf Fortress nor DFHack.
*/
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.IOException;
import java.nio.file.NoSuchFileException;
public class Dfhacktoggle {
private static Path statusfile = "dfhack-status";
private boolean dfhack = false;
private byte[] fileArray = new byte[1];
private byte[] active = new byte[1];
private byte[] inactive = new byte[1];
private file dfhacksdl = "SDLdfhack.dll";
private file vanillasdl = "SDLreal.dll";
private file sdl = "SDL.dll";
active[] <byte> = 1;
inactive[] <byte> = 0;
public static void main(String[] args) {
try {
fileArray = Files.readAllBytes(file);
if (fileArray[0] == 1) {
p("DFHack is active. Deactivating...");
try {
if (vanillasdl.exists()) throw new java.io.IOException("File exists");
sdl.renameTo(dfhacksdl);
vanillasdl.renameTo(sdl);
Files.write(statusfile, inactive, WRITE);
} catch (IOException x) {
errp("DFHack could not be deactivated. Reinstalling the program will solve this.");
errp("Detailed info:");
errp("IOException: " + x);
} catch (NoSuchFileException x) {
errp("Status file could not be found. Reinstalling the program will solve this.");
errp("Detailed info:");
errp("NoSuchFileException: " + x);
}
} else if (fileArray[0] == 0) {
p("DFHack is inactive. Activating...");
try {
if(vanillasdl.exists()) throw new java.io.IOException("File exists");
sdl.renameTo(vanillasdl);
dfhacksdl.renameTo(sdl);
Files.write(statusfile, active, WRITE);
} catch (IOException x) {
errp("Status could not be checked. Reinstalling the program will solve this.");
errp("Detailed info:");
errp("IOException: " + x);
} catch (NoSuchFileException x) {
errp("Status file could not be found. Reinstalling the program will solve this.");
errp("Detailed info:");
errp("NoSuchFileException: " + x);
}
} else {
errp("DFHack's status could not be checked. Reinstalling the program will solve this.");
}
} catch (IOException x) {
errp("Status could not be checked. Reinstalling the program will solve this.");
errp("Detailed info:");
errp(x);
}
}
public void p(String txt) {
System.out.println(txt);
}
public void errp(String txt) {
System.err.println(txt);
}
}
The compiler returns this:
F:\Dfhack-swap>javac Dfhacktoggle.java
Dfhacktoggle:29: error: <identifier> expected
active[] <byte> = 1;
^
Dfhacktoggle:30: error: <identifier> expected
inactive[] <byte> = 0;
^

Your syntax is wrong there's no active[] <byte> = 1; in Java
If you want to assign it a value You can do it in this way
active[0] = 1;
inactive[0] = 0;
But there's no need for array to use it as a boolean you can just define it as a byte
byte active= 1;
byte inactive= 0;

Java Program that runs commands with Linux Terminal

My question is this, I am running some adb commands through the terminal. I wrote a tool; that will help make things easier. So back to the question, in order to make the command run, I have to enter a "password" on the terminal. So how do I what do I do to make the "password" part appear on a JOptionPane.showInputDialog box?
Here is what I have so far:
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import java.io.IOException;
import javax.swing.JFileChooser;
import javax.swing.JOptionPane;
import javax.swing.filechooser.FileNameExtensionFilter;
public class flash implements ActionListener {
private File runfile;
#Override
public void actionPerformed(ActionEvent arg0) {
{
JFileChooser adbflashfile = new JFileChooser("/home/local/ANT/arthm/Desktop/os");
FileNameExtensionFilter filter = new FileNameExtensionFilter(".py", "py");
adbflashfile.setFileFilter(filter);
int returnVal = adbflashfile.showOpenDialog(null);
if (returnVal == JFileChooser.APPROVE_OPTION) {
runfile = adbflashfile.getSelectedFile();
try {
Runtime.getRuntime().exec("sudo python ./flashimage.py");
} catch (IOException e1) {
e1.printStackTrace();
}
//This is where a real application would open the file.
System.out.println("File: " + runfile.getName() + ".");
} else {
JOptionPane.showMessageDialog(null, "Open command cancelled by user.");
}
System.out.println(returnVal);
}
};
}

You "could" read the process input and when you "detect" the password prompt, display a JOptionPane and request that the user enter the password.
You "could" prompt the user for the password before you start the process, knowing that you are going to need to send it to the process.
You would probably still need to monitor the output of the process to determine when you need to send the password though.
Let's start with...
Runtime.getRuntime().exec("sudo python ./flashimage.py");
You are ignoring the Process completely. Neither are you processing the output, but you have no means to provide input to the process...
Generally, Runtime#exec is problematic at best. You are far better of using ProcessBuilder....
// Build the command to be executed. Note that each parameter becomes
// it's own argument, this deals with parameters that contain spaces
// much better then Runtime#exec alone...
ProcessBuilder pb = new ProcessBuilder("sudo", "python", "./flashimage.py");
pb.redirectError();
InputStream is = null;
try {
Process p = pb.start();
is = p.getInputStream();
StringBuilder output = new StringBuilder(80);
int in = -1;
while ((in = is.read()) != -1) {
if (in != '\n') {
output.append((char)in);
// You will need to define PASSWORD_PROMPT
if (PASSWORD_PROMPT.equals(output.toString())) {
String text = JOptionPane.showInputDialog("Password");
OutputStream os = p.getOutputStream();
os.write(text.getBytes());
}
} else {
System.out.println(output.toString());
output.delete(0, output.length());
}
}
} catch (IOException exp) {
exp.printStackTrace();
} finally {
try {
is.close();
} catch (Exception e) {
}
}
Now, undoubtedly, someone will point out (at least) two problems with this approach...
JOptionPane.showInputDialog("Password"); will present a normal JTextField, which won't hide the password characters and
String is not the safest way to to store a password...
Instead, we should use a JPasswordField and convert the resulting char array to a byte array...
JPasswordField password = new JPasswordField(10);
JLabel label = new JLabel("Password: ");
JPanel panel = new JPanel();
panel.add(label);
panel.add(password);
int option = JOptionPane.showConfirmDialog(null, panel, "Password", JOptionPane.OK_CANCEL_OPTION);
if (option == JOptionPane.OK_OPTION) {
char[] userPassword = password.getPassword();
byte[] bytes = new byte[userPassword.length * 2];
for (int i = 0; i < userPassword.length; i++) {
bytes[i * 2] = (byte) (userPassword[i] >> 8);
bytes[i * 2 + 1] = (byte) userPassword[i];
}
os.write(bytes);
}

Child process I/O can be redirected, using Process class. You should be able to monitor the output & provide input (the password) into the child process.
See:
http://docs.oracle.com/javase/7/docs/api/java/lang/Process.html
http://docs.oracle.com/javase/7/docs/api/java/lang/ProcessBuilder.html

Add History to Custom Shell

I am creating a custom shell in Java. I have added history to it so that when up arrow is pressed it goes to the previous command, but the up arrow seems to not be working
Here is my code:
public class MyShell {
public static class JavaStringHistory
{
private List<String> history = new ArrayList<String>();
}
public static void main(String[] args) throws java.io.IOException {
JavaStringHistory javaStringHistory = new JavaStringHistory();
javaStringHistory.history.add("");
Integer indexOfHistory = 0;
String commandLine;
BufferedReader console = new BufferedReader
(new InputStreamReader(System.in));
//Break with Ctrl+C
while (true) {
//read the command
System.out.print("Shell>");
commandLine = console.readLine();
javaStringHistory.history.add(commandLine);
//if just a return, loop
if (commandLine.equals(""))
continue;
//history
if (commandLine.equals(KeyEvent.VK_UP))
{
System.out.println("up arrow");
}
//help command
if (commandLine.equals("help"))
{
System.out.println();
System.out.println();
System.out.println("Welcome to the shell");
System.out.println("Written by: Alex Frieden");
System.out.println("--------------------");
System.out.println();
System.out.println("Commands to use:");
System.out.println("1) cat");
System.out.println("2) exit");
System.out.println("3) clear");
System.out.println();
System.out.println();
System.out.println("---------------------");
System.out.println();
}
if (commandLine.equals("clear"))
{
for(int cls = 0; cls < 10; cls++ )
{
System.out.println();
}
}
if(commandLine.startsWith("cat"))
{
System.out.println("test");
//ProcessBuilder pb = new ProcessBuilder();
//pb = new ProcessBuilder(commandLine);
}
else
{
System.out.println("Incorrect Command");
}
if (commandLine.equals("exit"))
{
System.out.println("...Terminating the Virtual Machine");
System.out.println("...Done");
System.out.println("Please Close manually with Options > Close");
System.exit(0);
}
indexOfHistory++;
}
}
}
All I am getting is
Shell>^[[A
Incorrect Command
Shell>
Any thoughts?

There are several problems with your approach:
User blackSmith has mentioned before me that system console handling is platform-dependent when it comes to cursor key handling and similar topics.
BufferedReader.readLine is not a smart choice to use for history cycling in a shell because you want the shell to immediately react to cursor keys and not force the user to press Return or Enter. Reading whole lines is only required for user commands. Thus, you need to scan the keyboard input for each single character or key code and decide by yourself if it is e.g. a cursor key (up/down for history cycling, left/right for cursor movement within the command line) or delete/backspace for command line editing and so forth.
The text strings which are created by reading control characters via readLine can depend on the OS, maybe even on the shell and the character set (UTF-8, ISO-8859-1, US ASCII etc.) on the console.
Built-in shell editing functions like command history might get in the way with readLine, e.g. on Linux I see the "^[[A" stuff for cursor up, on Windows the cursor keys are passed through to the built-in command history feature of cmd.exe. I.e. you need to put the console in raw mode (line editing bypassed and no Enter key required) as opposed to cooked mode (line editing with Enter key required).
Anyway, so as to answer your initial question about how to find out which key codes are produced by BufferedReader.readLine, it is actually quite simple. Just dump the bytes to the console like so:
commandLine = console.readLine();
System.out.println("Entered command text: " + commandLine);
System.out.print ("Entered command bytes: ");
for (byte b : commandLine.getBytes())
System.out.print(b + ", ");
System.out.println();
Under Linux cursor up might be something like "27, 91, 65" or just "91, 65", depending on the terminal. cursor down ends with "66" instead on my system. So you could do something like:
public class MyShell {
private static final String UP_ARROW_1 = new String(new byte[] {91, 65});
private static final String UP_ARROW_2 = new String(new byte[] {27, 91, 65});
private static final String DN_ARROW_1 = new String(new byte[] {91, 66});
private static final String DN_ARROW_2 = new String(new byte[] {27, 91, 66});
// (...)
public static void main(String[] args) throws IOException {
// (...)
// history
else if (commandLine.startsWith(UP_ARROW_1) || commandLine.startsWith(UP_ARROW_2)) {
System.out.println("up arrow");
}
else if (commandLine.startsWith(DN_ARROW_1) || commandLine.startsWith(DN_ARROW_2)) {
System.out.println("down arrow");
}
// (...)
}
}
But all this is just for explanation or demonstration and so as to answer your question - I do like to get the bounty. ;-)
Maybe a way to go is not to re-invent the wheel and use the work of others, e.g. a framework like JLine. It is not perfect either from what I have heard, but goes way further than anything you can develop by yourself in a short time. Someone has written a short introductory blog post about JLine. The library seems to do just what you need. Enjoy!
Update: I gave JLine 2.11 a little try with this code sample (basically the one from the blog post plus tab filename completion:
import java.io.IOException;
import jline.TerminalFactory;
import jline.console.ConsoleReader;
import jline.console.completer.FileNameCompleter;
public class MyJLineShell {
public static void main(String[] args) {
try {
ConsoleReader console = new ConsoleReader();
console.addCompleter(new FileNameCompleter());
console.setPrompt("prompt> ");
String line = null;
while ((line = console.readLine()) != null) {
console.println(line);
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
TerminalFactory.get().restore();
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
It works nicely on Windows and Linux, but for me tab completion only works on Linux, not on Windows. Anyway, command history works well on both platforms.

VK_UP is an integer constant, while in.readLine() is a string.
They won't equal each other. Why don't you try to test for the code that appears in console usually when you click up arrow? So like:
if (in.readLine().equals("^[[A"))
and then you could clear the line, and write the command in the arraylist with the highest index.
Also, I tested this and found a bug. Change your if statements besides the first to else if; after any command it will eventually get to the else and display "Incorrect Command"

is it possible to get key presses from the console in java? [duplicate]

This question already has answers here:
Closed 11 years ago.
Possible Duplicate:
How to read a single char from the console in Java (as the user types it)?
Im making a rogu like for the console, but is it possible to get keystrokes as they are typed?
*edit i found JLine, can it do the job? and if so how?

No, you can't get keypresses from the console. Because the console is dependent on the system and changes from environment to environment and from run to run, you might have one console written in Java, one written in Perl, and one written in C++, depending on where you open the program. You might also have an invisible console (you double click the JAR file).
Fortunately, you can write your own console. Doing so is fairly simple.
Here's a sample one I wrote recently:
import java.awt.BorderLayout;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.util.ArrayList;
import javax.swing.JFrame;
import javax.swing.JTextArea;
import javax.swing.JTextField;
public class Input extends JFrame implements KeyListener{
private JTextArea out;
private JTextField in;
public Input(){
out = new JTextArea();
in = new JTextField();
this.add(out, BorderLayout.CENTER);
this.add(in, BorderLayout.SOUTH);
in.addKeyListener(this);
}
public void keyPressed(KeyEvent e) {
}
public void keyReleased(KeyEvent e) {
}
public void keyTyped(KeyEvent e) {
if(e.getKeyChar() == (int)'\n'){
e.consume();
process(in.getText());
in.setText("");
}
}
public void process(String s){
String text = out.getText();
out.setText(text + ((text.length() == 0) ? "" : "\n") + s);
String query = s.substring(0, s.indexOf(' '));
String param = s.substring(s.indexOf(' ') + 1);
ArrayList<String> args = new ArrayList<String>();
int i = 0;
boolean inQuotes = false;
StringBuffer activeString = new StringBuffer();
while(i < param.length()){
if(param.charAt(i) == ' ' && !inQuotes){
args.add(activeString.toString());
System.out.println(activeString.toString());
activeString.setLength(0); //FIXME:works???
} else if(param.charAt(i) == '"'){
inQuotes = !inQuotes;
} else {
activeString.append(param.charAt(i));
}
i++;
}
args.add(activeString.toString());
System.out.println(activeString.toString());
activeString.setLength(0); //FIXME:works???
for (String string : args) {
activeString.append(string + ", ");
}
out.setText(out.getText() + "\n\t" + "Query: " + query + "; args: " + activeString.toString());
}
public static void main(String[] args){
Input x = new Input();
x.setVisible(true);
x.setDefaultCloseOperation(EXIT_ON_CLOSE);
}
}
Basically, make a text field at BorderLayout.SOUTH, a text area at BorderLayout.CENTER and add a KeyListener to the text field. Then you will be able to read keypresses from the console. You'll also be able to launch the application without a console (e.g. put it in a JAR file and open it by clicking it)
TL;DR: No, but you can make your own and use that :D
Good luck!