diff --git a/app/src/main/java/org/tasks/dialogs/AlertDialogBuilder.java b/app/src/main/java/org/tasks/dialogs/AlertDialogBuilder.java
deleted file mode 100644
index 13743c240..000000000
--- a/app/src/main/java/org/tasks/dialogs/AlertDialogBuilder.java
+++ /dev/null
@@ -1,131 +0,0 @@
-package org.tasks.dialogs;
-
-import android.content.Context;
-import android.content.DialogInterface;
-import android.content.DialogInterface.OnClickListener;
-import android.view.View;
-import android.widget.ListAdapter;
-
-import androidx.appcompat.app.AlertDialog;
-
-import com.google.android.material.dialog.MaterialAlertDialogBuilder;
-
-import java.util.List;
-
-public class AlertDialogBuilder {
-
-  private final AlertDialog.Builder builder;
-  private final Context context;
-
-  AlertDialogBuilder(Context context) {
-    this.context = context;
-    builder = new MaterialAlertDialogBuilder(context);
-  }
-
-  public AlertDialogBuilder setMessage(int message, Object... formatArgs) {
-    return setMessage(context.getString(message, formatArgs));
-  }
-
-  public AlertDialogBuilder setMessage(String message) {
-    builder.setMessage(message);
-    return this;
-  }
-
-  public AlertDialogBuilder setPositiveButton(
-      int ok, DialogInterface.OnClickListener onClickListener) {
-    builder.setPositiveButton(ok, onClickListener);
-    return this;
-  }
-
-  public AlertDialogBuilder setNegativeButton(
-      int cancel, DialogInterface.OnClickListener onClickListener) {
-    builder.setNegativeButton(cancel, onClickListener);
-    return this;
-  }
-
-  public AlertDialogBuilder setTitle(int title) {
-    builder.setTitle(title);
-    return this;
-  }
-
-  public AlertDialogBuilder setTitle(int title, Object... formatArgs) {
-    builder.setTitle(context.getString(title, formatArgs));
-    return this;
-  }
-
-  public AlertDialogBuilder setItems(
-      List<String> strings, DialogInterface.OnClickListener onClickListener) {
-    return setItems(strings.toArray(new String[0]), onClickListener);
-  }
-
-  public AlertDialogBuilder setItems(
-      String[] strings, DialogInterface.OnClickListener onClickListener) {
-    builder.setItems(strings.clone(), onClickListener);
-    return this;
-  }
-
-  public AlertDialogBuilder setAdapter(
-      ListAdapter adapter, DialogInterface.OnClickListener onClickListener) {
-    builder.setAdapter(adapter, onClickListener);
-    return this;
-  }
-
-  public AlertDialogBuilder setView(View dialogView) {
-    builder.setView(dialogView);
-    return this;
-  }
-
-  public AlertDialogBuilder setOnCancelListener(DialogInterface.OnCancelListener onCancelListener) {
-    builder.setOnCancelListener(onCancelListener);
-    return this;
-  }
-
-  public AlertDialogBuilder setSingleChoiceItems(
-      List<String> strings, int selectedIndex, DialogInterface.OnClickListener onClickListener) {
-    return setSingleChoiceItems(strings.toArray(new String[0]), selectedIndex, onClickListener);
-  }
-
-  public AlertDialogBuilder setSingleChoiceItems(
-      String[] strings, int selectedIndex, OnClickListener onClickListener) {
-    builder.setSingleChoiceItems(strings, selectedIndex, onClickListener);
-    return this;
-  }
-
-  public AlertDialogBuilder setSingleChoiceItems(
-      ListAdapter adapter, int selectedIndex, DialogInterface.OnClickListener onClickListener) {
-    builder.setSingleChoiceItems(adapter, selectedIndex, onClickListener);
-    return this;
-  }
-
-  public AlertDialogBuilder setNeutralButton(
-      int resId, DialogInterface.OnClickListener onClickListener) {
-    builder.setNeutralButton(resId, onClickListener);
-    return this;
-  }
-
-  AlertDialogBuilder setTitle(String title) {
-    builder.setTitle(title);
-    return this;
-  }
-
-  public AlertDialogBuilder setOnDismissListener(
-      DialogInterface.OnDismissListener onDismissListener) {
-    builder.setOnDismissListener(onDismissListener);
-    return this;
-  }
-
-  public AlertDialogBuilder setCancelable(boolean cancelable) {
-    builder.setCancelable(cancelable);
-    return this;
-  }
-
-  public AlertDialog create() {
-    return builder.create();
-  }
-
-  public AlertDialog show() {
-    AlertDialog dialog = create();
-    dialog.show();
-    return dialog;
-  }
-}
diff --git a/app/src/main/java/org/tasks/dialogs/AlertDialogBuilder.kt b/app/src/main/java/org/tasks/dialogs/AlertDialogBuilder.kt
new file mode 100644
index 000000000..ce5e9e72f
--- /dev/null
+++ b/app/src/main/java/org/tasks/dialogs/AlertDialogBuilder.kt
@@ -0,0 +1,135 @@
+package org.tasks.dialogs
+
+import android.content.Context
+import android.content.DialogInterface
+import android.view.View
+import android.widget.ListAdapter
+import androidx.appcompat.app.AlertDialog
+import com.google.android.material.dialog.MaterialAlertDialogBuilder
+
+class AlertDialogBuilder internal constructor(private val context: Context) {
+    private val builder: AlertDialog.Builder
+
+    init {
+        builder = MaterialAlertDialogBuilder(context)
+    }
+
+    fun setMessage(message: Int, vararg formatArgs: Any?): AlertDialogBuilder {
+        return setMessage(context.getString(message, *formatArgs))
+    }
+
+    fun setMessage(message: String?): AlertDialogBuilder {
+        builder.setMessage(message)
+        return this
+    }
+
+    fun setPositiveButton(
+        ok: Int, onClickListener: DialogInterface.OnClickListener?
+    ): AlertDialogBuilder {
+        builder.setPositiveButton(ok, onClickListener)
+        return this
+    }
+
+    fun setNegativeButton(
+        cancel: Int, onClickListener: DialogInterface.OnClickListener?
+    ): AlertDialogBuilder {
+        builder.setNegativeButton(cancel, onClickListener)
+        return this
+    }
+
+    fun setTitle(title: Int): AlertDialogBuilder {
+        builder.setTitle(title)
+        return this
+    }
+
+    fun setTitle(title: Int, vararg formatArgs: Any?): AlertDialogBuilder {
+        builder.setTitle(context.getString(title, *formatArgs))
+        return this
+    }
+
+    fun setItems(
+        strings: List<String>, onClickListener: DialogInterface.OnClickListener?
+    ): AlertDialogBuilder {
+        return setItems(strings.toTypedArray(), onClickListener)
+    }
+
+    fun setItems(
+        strings: Array<String>, onClickListener: DialogInterface.OnClickListener?
+    ): AlertDialogBuilder {
+        builder.setItems(strings.clone(), onClickListener)
+        return this
+    }
+
+    fun setAdapter(
+        adapter: ListAdapter?, onClickListener: DialogInterface.OnClickListener?
+    ): AlertDialogBuilder {
+        builder.setAdapter(adapter, onClickListener)
+        return this
+    }
+
+    fun setView(dialogView: View?): AlertDialogBuilder {
+        builder.setView(dialogView)
+        return this
+    }
+
+    fun setOnCancelListener(onCancelListener: DialogInterface.OnCancelListener?): AlertDialogBuilder {
+        builder.setOnCancelListener(onCancelListener)
+        return this
+    }
+
+    fun setSingleChoiceItems(
+        strings: List<String>, selectedIndex: Int, onClickListener: DialogInterface.OnClickListener?
+    ): AlertDialogBuilder {
+        return setSingleChoiceItems(strings.toTypedArray(), selectedIndex, onClickListener)
+    }
+
+    fun setSingleChoiceItems(
+        strings: Array<String>?,
+        selectedIndex: Int,
+        onClickListener: DialogInterface.OnClickListener?
+    ): AlertDialogBuilder {
+        builder.setSingleChoiceItems(strings, selectedIndex, onClickListener)
+        return this
+    }
+
+    fun setSingleChoiceItems(
+        adapter: ListAdapter?, selectedIndex: Int, onClickListener: DialogInterface.OnClickListener?
+    ): AlertDialogBuilder {
+        builder.setSingleChoiceItems(adapter, selectedIndex, onClickListener)
+        return this
+    }
+
+    fun setNeutralButton(
+        resId: Int, onClickListener: DialogInterface.OnClickListener?
+    ): AlertDialogBuilder {
+        builder.setNeutralButton(resId, onClickListener)
+        return this
+    }
+
+    fun setTitle(title: String?): AlertDialogBuilder {
+        builder.setTitle(title)
+        return this
+    }
+
+    fun setOnDismissListener(
+        onDismissListener: DialogInterface.OnDismissListener?
+    ): AlertDialogBuilder {
+        builder.setOnDismissListener(onDismissListener)
+        return this
+    }
+
+    fun setCancelable(cancelable: Boolean): AlertDialogBuilder {
+        builder.setCancelable(cancelable)
+        return this
+    }
+
+    fun create(): AlertDialog {
+        return builder.create()
+    }
+
+    fun show(): AlertDialog {
+        val dialog = create()
+        dialog.show()
+        return dialog
+    }
+}
\ No newline at end of file