implement the toggle button

app/build.gradle

@@ -21,6 +21,7 @@ android {
 
 dependencies {
     compile fileTree(dir: 'libs', include: ['*.jar'])
-    testCompile 'junit:junit:4.12'
     compile 'com.android.support:appcompat-v7:23.1.1'
+
+    testCompile 'junit:junit:4.12'
 }

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

@@ -1,18 +1,38 @@
 package flashlight.simplemobiletools.com;
 
+import android.graphics.Color;
+import android.graphics.PorterDuff;
 import android.hardware.Camera;
 import android.os.Bundle;
 import android.support.v7.app.AppCompatActivity;
+import android.view.View;
+import android.widget.ImageView;
 
 public class MainActivity extends AppCompatActivity {
     private Camera camera;
     private Camera.Parameters params;
+    private boolean isFlashlightOn;
+    private ImageView toggleBtn;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
         setupCamera();
+
+        toggleBtn = (ImageView) findViewById(R.id.toggle_btn);
+        toggleBtn.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                isFlashlightOn = !isFlashlightOn;
+
+                if (isFlashlightOn) {
+                    enableFlashlight();
+                } else {
+                    disableFlashlight();
+                }
+            }
+        });
     }
 
     private void setupCamera() {
@@ -24,6 +44,18 @@ public class MainActivity extends AppCompatActivity {
         }
     }
 
+    private void enableFlashlight() {
+        params.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH);
+        camera.setParameters(params);
+        toggleBtn.getDrawable().setColorFilter(Color.GREEN, PorterDuff.Mode.SRC_ATOP);
+    }
+
+    private void disableFlashlight() {
+        params.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);
+        camera.setParameters(params);
+        toggleBtn.getDrawable().setColorFilter(Color.RED, PorterDuff.Mode.SRC_ATOP);
+    }
+
     private void releaseCamera() {
         if (camera != null) {
             camera.release();

app/src/main/res/layout/activity_main.xml

@@ -10,4 +10,9 @@
     android:paddingTop="@dimen/activity_vertical_margin"
     tools:context="flashlight.simplemobiletools.com.MainActivity">
 
+    <ImageView
+        android:id="@+id/toggle_btn"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:src="@mipmap/ic_launcher"/>
 </RelativeLayout>