Start Minecraft On Mac With Java

Question

I am trying to make a java program that will launch minecraft in offline mode with whatever username i want so i can have usernames like Notch and deadmau5 and i am using this code to launch it on mac and windows (Currently Testing on mac):

public void startMacMinecraft(String username) throws IOException,
        InterruptedException {
    System.out.println(defaultDirectory());

    String sysUser = System.getProperty("user.name");
    String commandString = "java -cp "
            + defaultDirectory()
            + "/minecraft/bin/minecraft.jar:"
            + defaultDirectory()
            + "/minecraft/bin/lwjgl.jar:"
            + defaultDirectory()
            + "/minecraft/bin/lwjgl_util.jar:"
            + defaultDirectory()
            + "/minecraft/bin/jinput.jar: -Djava.library.path="
            + defaultDirectory()
            + "/minecraft/bin/natives -Xmx1024M -Xms512M net.minecraft.client.Minecraft '"
            + username + "'";
    CommandLine command = CommandLine.parse(commandString);
    DefaultExecutor executor = new DefaultExecutor();
    int exitValue = executor.execute(command);
    System.out.println(exitValue);

    System.out.println("\nTry Two:\n");
    String javaExe = System.getProperty("java.home") + "/bin/java";

}

public void startWinMinecraft(String username) throws IOException,
        InterruptedException {
    String sysUser = System.getProperty("user.name");
    String commandString = "Java -Xms512m -Xmx1024m -cp \"%APPDATA%\\.minecraft\\bin\\*\" -Djava.library.path=\"%APPDATA%\\.minecraft\\bin\\natives net.minecraft.client.Minecraft \""
            + username + "\"";
    CommandLine command = CommandLine.parse(commandString);
    DefaultExecutor executor = new DefaultExecutor();
    int exitValue = executor.execute(command);
    System.out.println(exitValue);

}

private static String defaultDirectory() {
    String OS = System.getProperty("os.name").toUpperCase();
    if (OS.contains("WIN"))
        return System.getenv("APPDATA");
    else if (OS.contains("MAC"))
        return System.getProperty("user.home") + "/Library/Application "
                + "Support";
    else if (OS.contains("NUX"))
        return System.getProperty("user.home");
    return System.getProperty("user.dir");
}

Which i am trying to adapt from this applescript which i have run before and got from https://gaming.stackexchange.com/questions/46608/how-can-i-run-minecraft-in-offline-mode-on-os-x-and-still-have-my-name that i will paste right here:

property user_name : "Player"

display dialog "Enter A User Name" default answer "" buttons {"Cancel", "Continue"} default button 2
set the user_name to text returned of the result

set UsrApp to (path to current user folder)
set UsrApp_unx to POSIX path of UsrApp

set MineScript to "java -cp " & UsrApp_unx & "Library/Application\\ Support/minecraft/bin/minecraft.jar:" & UsrApp_unx & "Library/Application\\ Support/minecraft/bin/lwjgl.jar:" & UsrApp_unx & "Library/Application\\ Support/minecraft/bin/lwjgl_util.jar:" & UsrApp_unx & "Library/Application\\ Support/minecraft/bin/jinput.jar: -Djava.library.path=" & UsrApp_unx & "Library/Application\\ Support/minecraft/bin/natives -Xmx1024M -Xms512M net.minecraft.client.Minecraft '" & user_name & "'"

do shell script MineScript

When i run the applescript it works perfectly fine but when i run my adapted version it gives me a class not found error:

    Logging in as: Player
/Users/Connor/Library/Application Support
Exception in thread "main" java.lang.NoClassDefFoundError: Support/minecraft/bin/minecraft/jar:/Users/Connor/Library/Application
Caused by: java.lang.ClassNotFoundException: Support.minecraft.bin.minecraft.jar:.Users.Connor.Library.Application
    at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
org.apache.commons.exec.ExecuteException: Process exited with an error: 1 (Exit value: 1)
    at org.apache.commons.exec.DefaultExecutor.executeInternal(DefaultExecutor.java:377)
    at org.apache.commons.exec.DefaultExecutor.execute(DefaultExecutor.java:160)
    at org.apache.commons.exec.DefaultExecutor.execute(DefaultExecutor.java:147)
    at info.connorbp.GUIApp.LoginPanel.startMacMinecraft(LoginPanel.java:137)
    at info.connorbp.GUIApp.LoginPanel$1.actionPerformed(LoginPanel.java:82)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2028)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2351)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
    at java.awt.Component.processMouseEvent(Component.java:6375)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3267)
    at java.awt.Component.processEvent(Component.java:6140)
    at java.awt.Container.processEvent(Container.java:2083)
    at java.awt.Component.dispatchEventImpl(Component.java:4737)
    at java.awt.Container.dispatchEventImpl(Container.java:2141)
    at java.awt.Component.dispatchEvent(Component.java:4565)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4619)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4280)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4210)
    at java.awt.Container.dispatchEventImpl(Container.java:2127)
    at java.awt.Window.dispatchEventImpl(Window.java:2482)
    at java.awt.Component.dispatchEvent(Component.java:4565)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:684)
    at java.awt.EventQueue.access$000(EventQueue.java:85)
    at java.awt.EventQueue$1.run(EventQueue.java:643)
    at java.awt.EventQueue$1.run(EventQueue.java:641)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:98)
    at java.awt.EventQueue$2.run(EventQueue.java:657)
    at java.awt.EventQueue$2.run(EventQueue.java:655)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:654)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:296)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:211)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:201)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:196)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:188)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

does anyone know what i am doing wrong or how to fix it?

EDIT:

Even stranger yet, I went into the events area of the applescript area and found the exact command the applescript was running:

java -cp /Users/Connor/Library/Application\\ Support/minecraft/bin/minecraft.jar:/Users/Connor/Library/Application\\ Support/minecraft/bin/lwjgl.jar:/Users/Connor/Library/Application\\ Support/minecraft/bin/lwjgl_util.jar:/Users/Connor/Library/Application\\ Support/minecraft/bin/jinput.jar: -Djava.library.path=/Users/Connor/Library/Application\\ Support/minecraft/bin/natives -Xmx1024M -Xms512M net.minecraft.client.Minecraft 'username'

and even when a tried running the script that came directly from the applescript i got another java.lang.NoClassDefFoundError error, even though i took the command directly from the applescript that is working.

Answer 1

Oops, forgot about this question. I was actually just missing some of the code that was needed in order to launch minecraft.

Answer 2

In the default launcher, whatever username you provide gets used for offline mode, so writing a separate launcher is pointless.

In any case, decompiling the launcher should give us a pretty good idea of how to launch the game.

There is a lot of code so I recommend decompiling it yourself. For mac, JD-GUI does an alright job. For windows, I can't recommend a decompiler, but thats what google is for :)

After you get the launcher source code, have a peek at public void login(String userName, String password) in net.minecraft.LauncherFrame. Also relevant is net.minecraft.Launcher.

Reading through that should give you a pretty good idea of how to launch minecraft.