lets use Kotlin for this project

app/build.gradle

@@ -1,4 +1,5 @@
 apply plugin: 'com.android.application'
+apply plugin: 'kotlin-android'
 
 android {
     compileSdkVersion 23
@@ -17,10 +18,29 @@ android {
             proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
         }
     }
+    sourceSets {
+        main.java.srcDirs += 'src/main/kotlin'
+    }
 }
 
 dependencies {
     compile fileTree(dir: 'libs', include: ['*.jar'])
     testCompile 'junit:junit:4.12'
     compile 'com.android.support:appcompat-v7:23.4.0'
+    compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
+}
+
+repositories {
+    mavenCentral()
+}
+
+buildscript {
+    ext.kotlin_version = '1.0.3'
+    repositories {
+        mavenCentral()
+    }
+
+    dependencies {
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
+    }
 }

app/src/main/java/com/simplemobiletools/applauncher/MainActivity.java

@@ -1,13 +0,0 @@
-package com.simplemobiletools.applauncher;
-
-import android.os.Bundle;
-import android.support.v7.app.AppCompatActivity;
-
-public class MainActivity extends AppCompatActivity {
-
-    @Override
-    protected void onCreate(Bundle savedInstanceState) {
-        super.onCreate(savedInstanceState);
-        setContentView(R.layout.activity_main);
-    }
-}

app/src/main/kotlin/com/simplemobiletools/applauncher/MainActivity.kt

@@ -0,0 +1,12 @@
+package com.simplemobiletools.applauncher
+
+import android.os.Bundle
+import android.support.v7.app.AppCompatActivity
+
+class MainActivity : AppCompatActivity() {
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.activity_main)
+    }
+}