Add Settable interface and SliderUpdatable class

src/gui/Settable.java

@@ -0,0 +1,7 @@
+package gui;
+
+@FunctionalInterface
+public interface Settable<T> {
+
+  void set(T value);
+}

src/gui/SliderUpdater.java

@@ -0,0 +1,19 @@
+package gui;
+
+import java.util.function.Consumer;
+
+public class SliderUpdater<T> {
+
+  private final Settable<String> settable;
+  private final Consumer<T> function;
+
+  public SliderUpdater(Settable<String> settable, Consumer<T> function) {
+    this.settable = settable;
+    this.function = function;
+  }
+
+  public void update(T value) {
+    settable.set(value.toString());
+    function.accept(value);
+  }
+}