diff --git a/app/src/main/java/org/ntlab/developrx/JavaMainActivity.java b/app/src/main/java/org/ntlab/developrx/JavaMainActivity.java
index 585d373..cfc7e69 100644
--- a/app/src/main/java/org/ntlab/developrx/JavaMainActivity.java
+++ b/app/src/main/java/org/ntlab/developrx/JavaMainActivity.java
@@ -22,5 +22,6 @@
         findViewById(R.id.interval_btn).setOnClickListener(view -> rxProcess.interval());
         findViewById(R.id.timer_btn).setOnClickListener(view -> rxProcess.timer());
         findViewById(R.id.error_btn).setOnClickListener(view -> rxProcess.error());
+        findViewById(R.id.map_btn).setOnClickListener(view -> rxProcess.map());
     }
 }