API changes

api/src/main/java/me/filoghost/holographicdisplays/api/hologram/Hologram.java

@@ -6,119 +6,29 @@
 package me.filoghost.holographicdisplays.api.hologram;
 
 import me.filoghost.holographicdisplays.api.HolographicDisplaysAPI;
-import me.filoghost.holographicdisplays.api.hologram.line.HologramLine;
-import me.filoghost.holographicdisplays.api.hologram.line.ItemHologramLine;
-import me.filoghost.holographicdisplays.api.hologram.line.TextHologramLine;
 import org.bukkit.Location;
 import org.bukkit.World;
-import org.bukkit.inventory.ItemStack;
 import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
 
 /**
- * An object made of various lines, that can be items or holograms.
- * Holographic lines appear as a nametag without any entity below.
- * To create one, please see {@link HolographicDisplaysAPI#createHologram(Location)}.
+ * Entity to manage a group of vertically aligned lines, which display floating text and items.
+ * To create one see {@link HolographicDisplaysAPI}.
  *
  * @since 1
  */
 public interface Hologram {
 
     /**
-     * Appends a text line to end of this hologram.
-     *
-     * @param text the content of the line, can be null for an empty line
-     * @return the new TextLine appended
-     * @since 1
-     */
-    @NotNull TextHologramLine appendTextLine(@Nullable String text);
-
-    /**
-     * Appends an item line to end of this hologram.
-     *
-     * @param itemStack the content of the line
-     * @return the new ItemLine appended
-     * @since 1
-     */
-    @NotNull ItemHologramLine appendItemLine(@NotNull ItemStack itemStack);
-
-    /**
-     * Inserts a text line in this hologram.
-     *
-     * @param index the line is inserted before this index. If 0, the new line will be inserted before the first line.
-     * @param text the content of the line, can be null for an empty line
-     * @return the new TextLine inserted
-     * @throws IndexOutOfBoundsException if the index is out of range (index < 0 || index >= size())
-     * @since 1
-     */
-    @NotNull TextHologramLine insertTextLine(int index, @Nullable String text);
-
-    /**
-     * Inserts an item line in this hologram.
-     *
-     * @param index the line is inserted before this index. If 0, the new line will be inserted before the first line.
-     * @param itemStack the content of the line
-     * @return the new ItemLine inserted
-     * @throws IndexOutOfBoundsException if the index is out of range (index < 0 || index >= size())
-     * @since 1
-     */
-    @NotNull ItemHologramLine insertItemLine(int index, @NotNull ItemStack itemStack);
-
-    /**
-     * Finds the element at a given index in the lines.
-     *
-     * @param index the index of the line to retrieve.
-     * @return the hologram line at the given index, can be an {@link ItemHologramLine} or a {@link TextHologramLine}.
-     * @throws IndexOutOfBoundsException if the index is out of range (index < 0 || index >= size())
-     * @since 1
-     */
-    @NotNull HologramLine getLine(int index);
-
-    /**
-     * Removes a line at a given index.
-     *
-     * @param index the index of the line, that should be between 0 and size() - 1.
-     * @throws IndexOutOfBoundsException if the index is out of range (index < 0 || index >= size())
-     * @since 1
-     */
-    void removeLine(int index);
-
-    /**
-     * Removes a line.
-     *
-     * @param line the line to be removed.
-     * @return if the hologram contained the line
-     * @since 1
-     */
-    boolean removeLine(@NotNull HologramLine line);
-
-    /**
-     * Removes all the lines from this hologram.
+     * Returns the editable list of lines.
      *
      * @since 1
      */
-    void clearLines();
+    @NotNull HologramLines lines();
 
     /**
-     * Checks the amount of lines of the hologram.
+     * Returns the current position.
      *
-     * @return the amount of lines
-     * @since 1
-     */
-    int getLineCount();
-
-    /**
-     * The physical height of the hologram, counting all the lines.
-     *
-     * @return the height of the hologram, counting all the lines and the gaps between them
-     * @since 1
-     */
-    double getHeight();
-
-    /**
-     * Returns the hologram position.
-     *
-     * @return the hologram position
+     * @return the current position
      * @since 1
      */
     @NotNull HologramPosition getPosition();

api/src/main/java/me/filoghost/holographicdisplays/api/hologram/HologramLines.java

@@ -0,0 +1,113 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.api.hologram;
+
+import me.filoghost.holographicdisplays.api.hologram.line.HologramLine;
+import me.filoghost.holographicdisplays.api.hologram.line.ItemHologramLine;
+import me.filoghost.holographicdisplays.api.hologram.line.TextHologramLine;
+import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * The editable list of lines of a hologram.
+ *
+ * @since 1
+ */
+public interface HologramLines {
+
+    /**
+     * Adds a new text line at the end.
+     *
+     * @param text the content of the line, see {@link TextHologramLine#setText(String)}
+     * @return the created line
+     * @since 1
+     */
+    @NotNull TextHologramLine appendText(@Nullable String text);
+
+    /**
+     * Adds a new item line at the end.
+     *
+     * @param itemStack the content of the line, see {@link ItemHologramLine#setItemStack(ItemStack)}
+     * @return the created line
+     * @since 1
+     */
+    @NotNull ItemHologramLine appendItem(@NotNull ItemStack itemStack);
+
+    /**
+     * Inserts a new text line before the given index.
+     *
+     * @param beforeIndex the index before which the line is inserted, 0 to insert as first
+     * @param text the content of the line, see {@link TextHologramLine#setText(String)}
+     * @return the created line
+     * @throws IndexOutOfBoundsException if the index is out of range (index < 0 || index >= size())
+     * @since 1
+     */
+    @NotNull TextHologramLine insertText(int beforeIndex, @Nullable String text);
+
+    /**
+     * Inserts a new item line before the given index.
+     *
+     * @param beforeIndex the index before which the line is inserted, 0 to insert as first
+     * @param itemStack the content of the line, see {@link ItemHologramLine#setItemStack(ItemStack)}
+     * @return the created line
+     * @throws IndexOutOfBoundsException if the index is out of range (index < 0 || index >= size())
+     * @since 1
+     */
+    @NotNull ItemHologramLine insertItem(int beforeIndex, @NotNull ItemStack itemStack);
+
+    /**
+     * Returns the line at the given index.
+     *
+     * @param index the index of the line to retrieve
+     * @return the line at the given index
+     * @throws IndexOutOfBoundsException if the index is out of range (index < 0 || index >= size())
+     * @since 1
+     */
+    @NotNull HologramLine get(int index);
+
+    /**
+     * Removes the line at the given index.
+     *
+     * @param index the index of the line to remove
+     * @throws IndexOutOfBoundsException if the index is out of range (index < 0 || index >= size())
+     * @since 1
+     */
+    void remove(int index);
+
+    /**
+     * Removes a line.
+     *
+     * @param line the line to be removed
+     * @return if the line was found and removed
+     * @since 1
+     */
+    boolean remove(@NotNull HologramLine line);
+
+    /**
+     * Removes all the lines.
+     *
+     * @since 1
+     */
+    void clear();
+
+    /**
+     * Returns the amount of lines.
+     *
+     * @return the amount of lines
+     * @since 1
+     */
+    int size();
+
+    /**
+     * The total height of the lines, including the gaps between them.
+     *
+     * @return the total height of the lines
+     * @since 1
+     */
+    double getHeight();
+
+}

example/death-holograms/src/main/java/me/filoghost/example/deathholograms/DeathHolograms.java

@@ -41,8 +41,8 @@ public class DeathHolograms extends JavaPlugin implements Listener {
     public void onPlayerDeath(PlayerDeathEvent event) {
         Hologram hologram = holographicDisplaysAPI.createHologram(event.getEntity().getEyeLocation());
 
-        hologram.appendTextLine(ChatColor.RED + "Player " + ChatColor.GOLD + event.getEntity().getName() + ChatColor.RED + " died here!");
-        hologram.appendTextLine(ChatColor.GRAY + "Time of death: " + TIME_FORMATTER.format(Instant.now()));
+        hologram.lines().appendText(ChatColor.RED + "Player " + ChatColor.GOLD + event.getEntity().getName() + ChatColor.RED + " died here!");
+        hologram.lines().appendText(ChatColor.GRAY + "Time of death: " + TIME_FORMATTER.format(Instant.now()));
     }
 
 }

example/power-ups/src/main/java/me/filoghost/example/powerups/PowerUps.java

@@ -49,10 +49,10 @@ public class PowerUps extends JavaPlugin implements Listener {
 
             // Spawn the floating item with a label
             Hologram hologram = holographicDisplaysAPI.createHologram(event.getEntity().getLocation().add(0.0, 0.9, 0.0));
-            hologram.appendTextLine(ChatColor.AQUA + "" + ChatColor.BOLD + "Speed PowerUp");
-            ItemHologramLine icon = hologram.appendItemLine(new ItemStack(Material.SUGAR));
+            hologram.lines().appendText(ChatColor.AQUA + "" + ChatColor.BOLD + "Speed PowerUp");
+            ItemHologramLine itemLine = hologram.lines().appendItem(new ItemStack(Material.SUGAR));
 
-            icon.setPickupListener((Player player) -> {
+            itemLine.setPickupListener((Player player) -> {
                 // Play an effect
                 player.playEffect(hologram.getPosition().toLocation(), Effect.MOBSPAWNER_FLAMES, null);
 

plugin/src/main/java/me/filoghost/holographicdisplays/plugin/HolographicDisplays.java

@@ -177,10 +177,10 @@ public class HolographicDisplays extends FCommonsPlugin {
         hologramDatabase.createHolograms(internalHologramManager, errorCollector);
 
         for (APIHologram hologram : apiHologramManager.getHolograms()) {
-            hologram.getLines().updateLinePositions();
+            hologram.lines().updatePositions();
         }
         for (V2Hologram hologram : v2HologramManager.getHolograms()) {
-            hologram.getLines().updateLinePositions();
+            hologram.lines().updatePositions();
         }
     }
 

plugin/src/main/java/me/filoghost/holographicdisplays/plugin/api/v2/V2Hologram.java

@@ -44,7 +44,7 @@ public class V2Hologram extends BaseHologram implements Hologram {
     }
 
     @Override
-    public BaseHologramLines<V2HologramLine> getLines() {
+    public BaseHologramLines<V2HologramLine> lines() {
         return lines;
     }
 

plugin/src/main/java/me/filoghost/holographicdisplays/plugin/api/v2/V2HologramLine.java

@@ -15,7 +15,7 @@ public interface V2HologramLine extends HologramLine, EditableHologramLine {
 
     @Override
     default void removeLine() {
-        getParent().getLines().remove(this);
+        getParent().lines().remove(this);
     }
 
 }

plugin/src/main/java/me/filoghost/holographicdisplays/plugin/commands/subs/AddLineCommand.java

@@ -38,7 +38,7 @@ public class AddLineCommand extends LineEditingCommand implements QuickEditComma
 
         InternalHologramLine line = hologramEditor.parseHologramLine(hologram, serializedLine);
 
-        hologram.getLines().add(line);
+        hologram.lines().add(line);
         hologramEditor.saveChanges(hologram, ChangeType.EDIT_LINES);
 
         sender.sendMessage(ColorScheme.PRIMARY + "Line added.");

plugin/src/main/java/me/filoghost/holographicdisplays/plugin/commands/subs/CopyCommand.java

@@ -37,11 +37,11 @@ public class CopyCommand extends HologramSubCommand {
         InternalHologram toHologram = hologramEditor.getExistingHologram(args[1]);
 
         List<InternalHologramLine> clonedLines = new ArrayList<>();
-        for (InternalHologramLine line : fromHologram.getLines()) {
+        for (InternalHologramLine line : fromHologram.lines()) {
             clonedLines.add(hologramEditor.parseHologramLine(toHologram, line.getSerializedConfigValue()));
         }
 
-        toHologram.getLines().setAll(clonedLines);
+        toHologram.lines().setAll(clonedLines);
         hologramEditor.saveChanges(toHologram, ChangeType.EDIT_LINES);
 
         sender.sendMessage(ColorScheme.PRIMARY + "Lines of hologram \"" + fromHologram.getName() + "\""

plugin/src/main/java/me/filoghost/holographicdisplays/plugin/commands/subs/CreateCommand.java

@@ -67,7 +67,7 @@ public class CreateCommand extends HologramSubCommand {
             line = hologram.createTextLine(defaultText, defaultText.replace(ChatColor.COLOR_CHAR, '&'));
         }
 
-        hologram.getLines().add(line);
+        hologram.lines().add(line);
         hologramEditor.saveChanges(hologram, ChangeType.CREATE);
 
         hologramEditor.teleportLookingDown(player, player.getLocation());

plugin/src/main/java/me/filoghost/holographicdisplays/plugin/commands/subs/InfoCommand.java

@@ -37,7 +37,7 @@ public class InfoCommand extends LineEditingCommand implements QuickEditCommand
         DisplayFormat.sendTitle(sender, "Lines of the hologram \"" + hologram.getName() + "\"");
         int index = 0;
 
-        for (InternalHologramLine line : hologram.getLines()) {
+        for (InternalHologramLine line : hologram.lines()) {
             index++;
             sender.sendMessage(ColorScheme.SECONDARY_BOLD + index + ColorScheme.SECONDARY_DARK + ". "
                     + ColorScheme.SECONDARY + line.getSerializedConfigValue());

plugin/src/main/java/me/filoghost/holographicdisplays/plugin/commands/subs/InsertLineCommand.java

@@ -41,14 +41,14 @@ public class InsertLineCommand extends LineEditingCommand implements QuickEditCo
         int insertAfterIndex = CommandValidate.parseInteger(args[1]);
         String serializedLine = Strings.joinFrom(" ", args, 2);
 
-        int oldLinesAmount = hologram.getLines().size();
+        int oldLinesAmount = hologram.lines().size();
 
         CommandValidate.check(insertAfterIndex >= 0 && insertAfterIndex <= oldLinesAmount,
                 "The line number must be between 0 and " + oldLinesAmount + ".");
 
         InternalHologramLine line = hologramEditor.parseHologramLine(hologram, serializedLine);
 
-        hologram.getLines().insert(insertAfterIndex, line);
+        hologram.lines().insert(insertAfterIndex, line);
         hologramEditor.saveChanges(hologram, ChangeType.EDIT_LINES);
 
         if (insertAfterIndex == 0) {

plugin/src/main/java/me/filoghost/holographicdisplays/plugin/commands/subs/ReadImageCommand.java

@@ -114,9 +114,9 @@ public class ReadImageCommand extends LineEditingCommand {
         }
 
         if (!append) {
-            hologram.getLines().clear();
+            hologram.lines().clear();
         }
-        hologram.getLines().addAll(newLines);
+        hologram.lines().addAll(newLines);
         hologramEditor.saveChanges(hologram, ChangeType.EDIT_LINES);
 
         if (append) {

plugin/src/main/java/me/filoghost/holographicdisplays/plugin/commands/subs/ReadTextCommand.java

@@ -85,7 +85,7 @@ public class ReadTextCommand extends LineEditingCommand {
             }
         }
 
-        hologram.getLines().setAll(newLines);
+        hologram.lines().setAll(newLines);
         hologramEditor.saveChanges(hologram, ChangeType.EDIT_LINES);
 
         if (FileUtils.hasFileExtension(fileToRead, "jpg", "png", "jpeg", "gif")) {

plugin/src/main/java/me/filoghost/holographicdisplays/plugin/commands/subs/RemoveLineCommand.java

@@ -35,7 +35,7 @@ public class RemoveLineCommand extends LineEditingCommand implements QuickEditCo
         InternalHologram hologram = hologramEditor.getExistingHologram(args[0]);
 
         int lineNumber = CommandValidate.parseInteger(args[1]);
-        int linesAmount = hologram.getLines().size();
+        int linesAmount = hologram.lines().size();
 
         CommandValidate.check(lineNumber >= 1 && lineNumber <= linesAmount,
                 "The line number must be between 1 and " + linesAmount + ".");
@@ -44,7 +44,7 @@ public class RemoveLineCommand extends LineEditingCommand implements QuickEditCo
         CommandValidate.check(linesAmount >= 2,
                 "A hologram must always have at least 1 line. If you want to delete it, use /" + context.getRootLabel() + " delete.");
 
-        hologram.getLines().remove(index);
+        hologram.lines().remove(index);
         hologramEditor.saveChanges(hologram, ChangeType.EDIT_LINES);
 
         sender.sendMessage(ColorScheme.PRIMARY + "Line " + lineNumber + " removed.");

plugin/src/main/java/me/filoghost/holographicdisplays/plugin/commands/subs/SetLineCommand.java

@@ -38,7 +38,7 @@ public class SetLineCommand extends LineEditingCommand implements QuickEditComma
         String serializedLine = Strings.joinFrom(" ", args, 2);
 
         int lineNumber = CommandValidate.parseInteger(args[1]);
-        int linesAmount = hologram.getLines().size();
+        int linesAmount = hologram.lines().size();
 
         CommandValidate.check(lineNumber >= 1 && lineNumber <= linesAmount,
                 "The line number must be between 1 and " + linesAmount + ".");
@@ -46,7 +46,7 @@ public class SetLineCommand extends LineEditingCommand implements QuickEditComma
 
         InternalHologramLine line = hologramEditor.parseHologramLine(hologram, serializedLine);
 
-        hologram.getLines().set(index, line);
+        hologram.lines().set(index, line);
         hologramEditor.saveChanges(hologram, ChangeType.EDIT_LINES);
 
         sender.sendMessage(ColorScheme.PRIMARY + "Line " + lineNumber + " changed.");

plugin/src/main/java/me/filoghost/holographicdisplays/plugin/config/HologramConfig.java

@@ -30,7 +30,7 @@ public class HologramConfig {
     public HologramConfig(InternalHologram hologram) {
         this.name = hologram.getName();
         this.serializedLines = new ArrayList<>();
-        for (InternalHologramLine line : hologram.getLines()) {
+        for (InternalHologramLine line : hologram.lines()) {
             serializedLines.add(line.getSerializedConfigValue());
         }
 
@@ -70,7 +70,7 @@ public class HologramConfig {
             }
         }
 
-        hologram.getLines().addAll(lines);
+        hologram.lines().addAll(lines);
     }
 
     private BaseHologramPosition parsePosition() throws HologramLoadException {

plugin/src/main/java/me/filoghost/holographicdisplays/plugin/format/DisplayFormat.java

@@ -89,7 +89,7 @@ public class DisplayFormat {
     public static void sendHologramSummary(CommandSender sender, InternalHologram hologram, boolean showWorld) {
         BaseHologramPosition position = hologram.getPosition();
         sender.sendMessage(ColorScheme.SECONDARY_DARK + "- " + ColorScheme.SECONDARY_BOLD + hologram.getName()
-                + ColorScheme.SECONDARY_DARK + " (" + hologram.getLines().size() + " lines) at "
+                + ColorScheme.SECONDARY_DARK + " (" + hologram.lines().size() + " lines) at "
                 + (showWorld ? "world: \"" + position.getWorldName() + "\", " : "")
                 + "x: " + position.getBlockX() + ", "
                 + "y: " + position.getBlockY() + ", "

plugin/src/main/java/me/filoghost/holographicdisplays/plugin/hologram/api/APIHologram.java

@@ -7,20 +7,16 @@ package me.filoghost.holographicdisplays.plugin.hologram.api;
 
 import me.filoghost.fcommons.Preconditions;
 import me.filoghost.holographicdisplays.api.hologram.Hologram;
-import me.filoghost.holographicdisplays.api.hologram.line.HologramLine;
 import me.filoghost.holographicdisplays.plugin.hologram.base.BaseHologram;
-import me.filoghost.holographicdisplays.plugin.hologram.base.BaseHologramLines;
 import me.filoghost.holographicdisplays.plugin.hologram.base.BaseHologramPosition;
 import me.filoghost.holographicdisplays.plugin.hologram.tracking.LineTrackerManager;
 import org.bukkit.entity.Player;
-import org.bukkit.inventory.ItemStack;
 import org.bukkit.plugin.Plugin;
 import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
 
 public class APIHologram extends BaseHologram implements Hologram {
 
-    private final BaseHologramLines<APIHologramLine> lines;
+    private final APIHologramLines lines;
     private final Plugin plugin;
     private final APIHologramManager apiHologramManager;
     private final DefaultVisibilitySettings visibilitySettings;
@@ -34,14 +30,14 @@ public class APIHologram extends BaseHologram implements Hologram {
             LineTrackerManager lineTrackerManager) {
         super(position, lineTrackerManager);
         Preconditions.notNull(plugin, "plugin");
-        this.lines = new BaseHologramLines<>(this);
+        this.lines = new APIHologramLines(this);
         this.plugin = plugin;
         this.apiHologramManager = apiHologramManager;
         this.visibilitySettings = new DefaultVisibilitySettings();
     }
 
     @Override
-    public BaseHologramLines<APIHologramLine> getLines() {
+    public @NotNull APIHologramLines lines() {
         return lines;
     }
 
@@ -50,79 +46,6 @@ public class APIHologram extends BaseHologram implements Hologram {
         return plugin;
     }
 
-    @Override
-    public @NotNull APIHologramLine getLine(int index) {
-        return lines.get(index);
-    }
-
-    @Override
-    public @NotNull APITextLine appendTextLine(@Nullable String text) {
-        checkNotDeleted();
-
-        APITextLine line = new APITextLine(this, text);
-        lines.add(line);
-        return line;
-    }
-
-    @Override
-    public @NotNull APIItemLine appendItemLine(@NotNull ItemStack itemStack) {
-        Preconditions.notNull(itemStack, "itemStack");
-        checkNotDeleted();
-
-        APIItemLine line = new APIItemLine(this, itemStack);
-        lines.add(line);
-        return line;
-    }
-
-    @Override
-    public @NotNull APITextLine insertTextLine(int index, @Nullable String text) {
-        checkNotDeleted();
-
-        APITextLine line = new APITextLine(this, text);
-        lines.add(line);
-        return line;
-    }
-
-    @Override
-    public @NotNull APIItemLine insertItemLine(int index, @NotNull ItemStack itemStack) {
-        Preconditions.notNull(itemStack, "itemStack");
-        checkNotDeleted();
-
-        APIItemLine line = new APIItemLine(this, itemStack);
-        lines.add(line);
-        return line;
-    }
-
-    @Override
-    public void removeLine(int index) {
-        checkNotDeleted();
-
-        lines.remove(index);
-    }
-
-    @Override
-    public boolean removeLine(@NotNull HologramLine line) {
-        checkNotDeleted();
-
-        if (line instanceof APIHologramLine) {
-            return lines.remove((APIHologramLine) line);
-        } else {
-            return false;
-        }
-    }
-
-    @Override
-    public void clearLines() {
-        checkNotDeleted();
-
-        lines.clear();
-    }
-
-    @Override
-    public int getLineCount() {
-        return getLines().size();
-    }
-
     @Override
     public void setAllowPlaceholders(boolean allowPlaceholders) {
         checkNotDeleted();
@@ -147,11 +70,6 @@ public class APIHologram extends BaseHologram implements Hologram {
         return visibilitySettings.isVisibleTo(player);
     }
 
-    @Override
-    public double getHeight() {
-        return lines.getHeight();
-    }
-
     @Override
     public @NotNull DefaultVisibilitySettings getVisibilitySettings() {
         return visibilitySettings;

plugin/src/main/java/me/filoghost/holographicdisplays/plugin/hologram/api/APIHologramLines.java

@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) filoghost and contributors
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package me.filoghost.holographicdisplays.plugin.hologram.api;
+
+import me.filoghost.fcommons.Preconditions;
+import me.filoghost.holographicdisplays.api.hologram.HologramLines;
+import me.filoghost.holographicdisplays.api.hologram.line.HologramLine;
+import me.filoghost.holographicdisplays.api.hologram.line.ItemHologramLine;
+import me.filoghost.holographicdisplays.api.hologram.line.TextHologramLine;
+import me.filoghost.holographicdisplays.plugin.hologram.base.BaseHologramLines;
+import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+public class APIHologramLines extends BaseHologramLines<APIHologramLine> implements HologramLines {
+
+    private final APIHologram hologram;
+
+    public APIHologramLines(APIHologram hologram) {
+        super(hologram);
+        this.hologram = hologram;
+    }
+
+    @Override
+    public @NotNull TextHologramLine appendText(@Nullable String text) {
+        checkNotDeleted();
+
+        APITextLine line = new APITextLine(hologram, text);
+        super.add(line);
+        return line;
+    }
+
+    @Override
+    public @NotNull ItemHologramLine appendItem(@NotNull ItemStack itemStack) {
+        Preconditions.notNull(itemStack, "itemStack");
+        checkNotDeleted();
+
+        APIItemLine line = new APIItemLine(hologram, itemStack);
+        super.add(line);
+        return line;
+    }
+
+    @Override
+    public @NotNull TextHologramLine insertText(int beforeIndex, @Nullable String text) {
+        checkNotDeleted();
+
+        APITextLine line = new APITextLine(hologram, text);
+        super.insert(beforeIndex, line);
+        return line;
+    }
+
+    @Override
+    public @NotNull ItemHologramLine insertItem(int beforeIndex, @NotNull ItemStack itemStack) {
+        Preconditions.notNull(itemStack, "itemStack");
+        checkNotDeleted();
+
+        APIItemLine line = new APIItemLine(hologram, itemStack);
+        super.insert(beforeIndex, line);
+        return line;
+    }
+
+    @Override
+    public boolean remove(@NotNull HologramLine line) {
+        if (line instanceof APIHologramLine) {
+            return super.remove((APIHologramLine) line);
+        } else {
+            return false;
+        }
+    }
+
+}

plugin/src/main/java/me/filoghost/holographicdisplays/plugin/hologram/base/BaseHologram.java

@@ -26,7 +26,7 @@ public abstract class BaseHologram extends BaseHologramComponent {
         this.lineTrackerManager = lineTrackerManager;
     }
 
-    public abstract BaseHologramLines<? extends EditableHologramLine> getLines();
+    public abstract BaseHologramLines<? extends EditableHologramLine> lines();
 
     protected abstract boolean isVisibleTo(Player player);
 
@@ -39,7 +39,7 @@ public abstract class BaseHologram extends BaseHologramComponent {
     @Override
     public final void setDeleted() {
         super.setDeleted();
-        getLines().setDeleted();
+        lines().setDeleted();
     }
 
     public @NotNull BaseHologramPosition getPosition() {
@@ -71,7 +71,7 @@ public abstract class BaseHologram extends BaseHologramComponent {
         checkNotDeleted();
 
         position.set(worldName, x, y, z);
-        getLines().updateLinePositions();
+        lines().updatePositions();
     }
 
     protected void onWorldLoad(World world) {
@@ -98,7 +98,7 @@ public abstract class BaseHologram extends BaseHologramComponent {
     public String toString() {
         return "Hologram{"
                 + "position=" + position
-                + ", lines=" + getLines()
+                + ", lines=" + lines()
                 + ", deleted=" + isDeleted()
                 + "}";
     }

plugin/src/main/java/me/filoghost/holographicdisplays/plugin/hologram/base/BaseHologramLines.java

@@ -7,6 +7,7 @@ package me.filoghost.holographicdisplays.plugin.hologram.base;
 
 import me.filoghost.holographicdisplays.api.hologram.HologramPosition;
 import me.filoghost.holographicdisplays.plugin.config.Settings;
+import org.jetbrains.annotations.NotNull;
 
 import java.util.ArrayList;
 import java.util.Collections;
@@ -38,7 +39,7 @@ public class BaseHologramLines<T extends EditableHologramLine> implements Iterab
         return lines.isEmpty();
     }
 
-    public T get(int index) {
+    public @NotNull T get(int index) {
         return lines.get(index);
     }
 
@@ -46,21 +47,21 @@ public class BaseHologramLines<T extends EditableHologramLine> implements Iterab
         checkNotDeleted();
 
         lines.add(line);
-        updateLinePositions();
+        updatePositions();
     }
 
     public void addAll(List<? extends T> newLines) {
         checkNotDeleted();
 
         lines.addAll(newLines);
-        updateLinePositions();
+        updatePositions();
     }
 
-    public void insert(int afterIndex, T line) {
+    public void insert(int beforeIndex, T line) {
         checkNotDeleted();
 
-        lines.add(afterIndex, line);
-        updateLinePositions();
+        lines.add(beforeIndex, line);
+        updatePositions();
     }
 
     public void set(int index, T line) {
@@ -68,7 +69,7 @@ public class BaseHologramLines<T extends EditableHologramLine> implements Iterab
 
         T previousLine = lines.set(index, line);
         previousLine.setDeleted();
-        updateLinePositions();
+        updatePositions();
     }
 
     public void setAll(List<T> newLines) {
@@ -76,14 +77,14 @@ public class BaseHologramLines<T extends EditableHologramLine> implements Iterab
 
         clear();
         lines.addAll(newLines);
-        updateLinePositions();
+        updatePositions();
     }
 
     public void remove(int index) {
         checkNotDeleted();
 
         lines.remove(index).setDeleted();
-        updateLinePositions();
+        updatePositions();
     }
 
     public boolean remove(T line) {
@@ -92,7 +93,7 @@ public class BaseHologramLines<T extends EditableHologramLine> implements Iterab
         boolean removed = lines.remove(line);
         if (removed) {
             line.setDeleted();
-            updateLinePositions();
+            updatePositions();
         }
         return removed;
     }
@@ -114,7 +115,7 @@ public class BaseHologramLines<T extends EditableHologramLine> implements Iterab
      * The top part of the first line should be exactly on the Y position of the hologram.
      * The second line is below the first, and so on.
      */
-    public void updateLinePositions() {
+    public void updatePositions() {
         HologramPosition hologramPosition = hologram.getPosition();
         double currentLineY = hologramPosition.getY();
 
@@ -151,7 +152,7 @@ public class BaseHologramLines<T extends EditableHologramLine> implements Iterab
         }
     }
 
-    private void checkNotDeleted() {
+    protected void checkNotDeleted() {
         hologram.checkNotDeleted();
     }
 

plugin/src/main/java/me/filoghost/holographicdisplays/plugin/hologram/internal/InternalHologram.java

@@ -26,7 +26,7 @@ public class InternalHologram extends BaseHologram {
     }
 
     @Override
-    public BaseHologramLines<InternalHologramLine> getLines() {
+    public BaseHologramLines<InternalHologramLine> lines() {
         return lines;
     }