#11 - Partial work

src/main/java/com/lb_stuff/mcmodify/minecraft/Chunk.java

@@ -12,7 +12,7 @@
 import java.lang.reflect.InvocationTargetException;
 
 /**
- *
+ * @see <a href="http://minecraft.gamepedia.com/Chunk_format">Chunk format</a> on the Minecraft Wiki
  */
 public class Chunk
 {

src/main/java/com/lb_stuff/mcmodify/minecraft/Region.java

@@ -18,6 +18,7 @@
 
 /**
  * Region file reader/writer
+ * @see <a href="http://minecraft.gamepedia.com/Region_file_format">Region file format</a> on the Minecraft Wiki
  */
 public final class Region
 {

src/main/java/com/lb_stuff/mcmodify/minecraft/ServerList.java

@@ -0,0 +1,27 @@
+package com.lb_stuff.mcmodify.minecraft;
+
+import java.io.File;
+
+/**
+ * @see <a href="http://minecraft.gamepedia.com/Servers.dat_format">Servers.dat format</a> on the Minecraft Wiki
+ */
+public class ServerList
+{
+	private final File dir;
+	public ServerList(File mcdir)
+	{
+		if(mcdir.isDirectory())
+		{
+			dir = mcdir;
+			return;
+		}
+		else if(mcdir.isFile() && mcdir.getName().equalsIgnoreCase("servers.dat"))
+		{
+			dir = mcdir.getParentFile();
+			return;
+		}
+		throw new IllegalArgumentException("\"mcdir\" must be the Minecraft directory or servers.dat file");
+	}
+
+	//
+}

src/main/java/com/lb_stuff/mcmodify/minecraft/World.java

@@ -0,0 +1,75 @@
+package com.lb_stuff.mcmodify.minecraft;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.util.InputMismatchException;
+import java.util.NoSuchElementException;
+import java.util.Scanner;
+
+/**
+ * @see <a href="http://minecraft.gamepedia.com/Level_format">Level format</a> on the Minecraft Wiki
+ */
+public class World
+{
+	private final File dir;
+	public World(File level)
+	{
+		if(level.isDirectory())
+		{
+			dir = level;
+			return;
+		}
+		else if(level.isFile() && level.getName().equalsIgnoreCase("level.dat"))
+		{
+			dir = level.getParentFile();
+			return;
+		}
+		throw new IllegalArgumentException("\"level\" must be the world directory or level.dat file");
+	}
+
+	private File getLockFile()
+	{
+		return new File(dir, "session.lock");
+	}
+	private Long locktimestamp = null;
+	public void lock() throws IOException
+	{
+		File f = getLockFile();
+		if(!f.delete() || !f.createNewFile())
+		{
+			throw new IOException("Cannot recreate session.lock");
+		}
+		Long t;
+		try(PrintWriter pw = new PrintWriter(f))
+		{
+			t = System.currentTimeMillis();
+			pw.print((long)t);
+		}
+		locktimestamp = t;
+	}
+	public boolean isLocked()
+	{
+		if(locktimestamp == null)
+		{
+			return false;
+		}
+		try(Scanner s = new Scanner(getLockFile()))
+		{
+			return locktimestamp.equals(s.nextLong());
+		}
+		catch(IOException|NoSuchElementException e)
+		{
+			return false;
+		}
+	}
+	public void throwIfNotLocked() throws IllegalStateException
+	{
+		if(!isLocked())
+		{
+			throw new IllegalStateException("World is no longer locked by this instance/program");
+		}
+	}
+
+	//
+}