Improves writing speed when not using a GUI

Uses buffered writers instead of System.out
Uses a GUI for writing JarBuilder messages
Adds some missing comments to the jar builder

src/main/java/net/knarcraft/minecraftserverlauncher/userinterface/MessageHandler.java

@@ -1,6 +1,9 @@
 package net.knarcraft.minecraftserverlauncher.userinterface;
 
 import javax.swing.*;
+import java.io.BufferedWriter;
+import java.io.IOException;
+import java.io.OutputStreamWriter;
 
 /**
  * This class handles displaying messages to the user
@@ -8,6 +11,7 @@ import javax.swing.*;
 public abstract class MessageHandler implements GUI {
 
     private final boolean silent;
+    private final BufferedWriter writer;
 
     /***
      * Initializes a new message handler
@@ -16,12 +20,18 @@ public abstract class MessageHandler implements GUI {
      */
     public MessageHandler(boolean silent) {
         this.silent = silent;
+        this.writer = new BufferedWriter(new OutputStreamWriter(System.out));
     }
 
     @Override
     public void showError(String title, String message) {
         if (silent) {
+            try {
+                writer.write(message);
+                writer.flush();
+            } catch (IOException e) {
                 System.out.println(message);
+            }
         } else {
             showJOptionPane(title, message, JOptionPane.ERROR_MESSAGE);
         }
@@ -35,7 +45,12 @@ public abstract class MessageHandler implements GUI {
     @Override
     public void showMessage(String title, String message) {
         if (silent) {
+            try {
+                writer.write(message);
+                writer.flush();
+            } catch (IOException e) {
                 System.out.println(message);
+            }
         } else {
             showJOptionPane(title, message, JOptionPane.INFORMATION_MESSAGE);
         }

src/main/java/net/knarcraft/minecraftserverlauncher/utility/JarBuilder.java

@@ -2,6 +2,7 @@ package net.knarcraft.minecraftserverlauncher.utility;
 
 import net.knarcraft.minecraftserverlauncher.Main;
 import net.knarcraft.minecraftserverlauncher.server.ServerVersionContainer;
+import net.knarcraft.minecraftserverlauncher.userinterface.GUI;
 
 import java.io.BufferedReader;
 import java.io.BufferedWriter;
@@ -11,16 +12,27 @@ import java.io.InputStreamReader;
 import java.io.OutputStreamWriter;
 import java.nio.file.Paths;
 
+/**
+ * The jar builder is responsible for building the newest Spigot and CraftBukkit .jar files using BuildTools
+ */
 public class JarBuilder {
 
     private final String buildDirectory;
     private final String jarDirectory;
     private final ServerVersionContainer versionContainer;
+    private final GUI gui;
 
-    public JarBuilder(String buildDirectory, String jarDirectory, ServerVersionContainer versionContainer) {
+    /**
+     * Instantiates a new jar builder
+     * @param buildDirectory <p>The directory containing BuildTool files</p>
+     * @param jarDirectory <p>The directory containing downloaded .jar files</p>
+     * @param gui <p>The GUI to write messages to</p>
+     */
+    public JarBuilder(String buildDirectory, String jarDirectory, GUI gui) {
         this.buildDirectory = buildDirectory;
         this.jarDirectory = jarDirectory;
-        this.versionContainer = versionContainer;
+        this.gui = gui;
+        this.versionContainer = ServerVersionContainer.getInstance();
     }
 
     /**
@@ -31,9 +43,9 @@ public class JarBuilder {
         ProcessBuilder processBuilder = new ProcessBuilder("java", "-jar", "BuildTools.jar", "--rev",
                 "latest", "--output-dir", jarDirectory);
         executeBuildProcess(processBuilder);
-        System.out.println("Finished building spigot .jar. Moving it to the correct location");
+        gui.setStatus("Finished building spigot .jar. Moving it to the correct location");
         moveBuiltJar("spigot-", "SpigotLatest.jar");
-        System.out.println("Finished moving spigot .jar");
+        gui.setStatus("Finished moving spigot .jar");
     }
 
     /**
@@ -44,9 +56,9 @@ public class JarBuilder {
         ProcessBuilder processBuilder = new ProcessBuilder("java", "-jar", "BuildTools.jar", "--compile",
                 "craftbukkit", "--rev", "latest", "--output-dir", jarDirectory);
         executeBuildProcess(processBuilder);
-        System.out.println("Finished building craftbukkit .jar. Moving it to the correct location");
+        gui.setStatus("Finished building craftbukkit .jar. Moving it to the correct location");
         moveBuiltJar("craftbukkit-", "BukkitLatest.jar");
-        System.out.println("Finished moving craftbukkit .jar");
+        gui.setStatus("Finished moving craftbukkit .jar");
     }
 
     /**
@@ -111,7 +123,7 @@ public class JarBuilder {
             writer.flush();
 
             if (process.exitValue() == 0) {
-                System.out.println("Jar building process finished successfully.");
+                gui.setStatus("Jar building process finished successfully.");
             } else {
                 throw new RuntimeException("Jar building process failed with exit code " + process.exitValue() + ".");
             }

src/test/java/net/knarcraft/minecraftserverlauncher/userinterface/FakeGUI.java

@@ -1,20 +1,31 @@
 package net.knarcraft.minecraftserverlauncher.userinterface;
 
+import java.io.BufferedWriter;
 import java.io.File;
+import java.io.IOException;
+import java.io.OutputStreamWriter;
 
 public class FakeGUI extends MessageHandler implements GUI {
 
+    private final BufferedWriter writer;
+
     /***
      * Initializes a new fake gui
      */
     public FakeGUI() {
         super(true);
+        this.writer = new BufferedWriter(new OutputStreamWriter(System.out));
     }
 
     @Override
     public void setStatus(String message) {
+        try {
+            writer.write(message);
+            writer.flush();
+        } catch (IOException e) {
             System.out.println(message);
         }
+    }
 
     @Override
     public File askForDirectory(String prompt) {

src/test/java/net/knarcraft/minecraftserverlauncher/utility/JarBuilderTest.java

@@ -1,7 +1,7 @@
 package net.knarcraft.minecraftserverlauncher.utility;
 
 import net.knarcraft.minecraftserverlauncher.Main;
-import net.knarcraft.minecraftserverlauncher.server.ServerVersionContainer;
+import net.knarcraft.minecraftserverlauncher.userinterface.FakeGUI;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.MethodOrderer;
 import org.junit.jupiter.api.Order;
@@ -27,7 +27,7 @@ public class JarBuilderTest {
                 "BuildTools" + File.separator;
         jarDirectory = Main.getApplicationWorkDirectory() + File.separator + "files" + File.separator +
                 "testjars" + File.separator;
-        jarBuilder = new JarBuilder(targetDirectory, jarDirectory, ServerVersionContainer.getInstance());
+        jarBuilder = new JarBuilder(targetDirectory, jarDirectory, new FakeGUI());
         removeBuildToolsFiles();
     }