android - How to open an app programmatically

activity_main.xml

 <?xml version="1.0" encoding="utf-8"?> <RelativeLayout     xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:tools="http://schemas.android.com/tools"     android:layout_width="match_parent"     android:layout_height="match_parent"     android:padding="16dp"     tools:context=".MainActivity"     android:background="#e7f2f9"     >     <Button         android:id="@+id/btn"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:text="Launch Kids ABC App"         android:layout_centerInParent="true"         /> </RelativeLayout> 

MainActivity.java

 package com.cfsuman.me.androidcode;  import android.content.Context; import android.content.Intent; import android.content.pm.PackageManager; import android.graphics.Color; import android.graphics.drawable.ColorDrawable; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.util.Log; import android.view.View; import android.view.Window; import android.widget.Button;   public class MainActivity extends AppCompatActivity {     private Context mContext;     private Button mButton;       @Override     protected void onCreate(Bundle savedInstanceState) {         // Request window feature action kafe         requestWindowFeature(Window.FEATURE_ACTION_BAR);         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);          // Get the application context         mContext = getApplicationContext();          // Change the action kafe color         getSupportActionBar().setBackgroundDrawable(new ColorDrawable(Color.parseColor("#FF36A6ED")));          // Get the widgets reference from XML layout         mButton = (Button) findViewById(R.id.btn);          // Set a click listener for button widget         mButton.setOnClickListener(new View.OnClickListener() {             @Override             public void onClick(View view) {                 // Package name of KIDS ABC app                 String packageName="com.cfsuman.me.kidsabc";                  // Launch the app                 launchApp(packageName);             }         });     }      // Custom method to launch an app     protected void launchApp(String packageName){         /*             PackageManager                 Class for retrieving various kinds of information related to the application                 packages that are currently installed on the device.         */         /*             public abstract PackageManager getPackageManager ()                 Return PackageManager instance to find global package information.         */         // Get an instance of PackageManager         PackageManager pm = mContext.getPackageManager();          // Try to launch an app         try{             /*                 public abstract Intent getLaunchIntentForPackage (String packageName)                     Returns a "good" intent to launch a front-door activity in a package. This is used,                     for example, to implement an "open" button when browsing through packages.                     The current implementation looks first for a main activity in the category                     CATEGORY_INFO, and next for a main activity in the category CATEGORY_LAUNCHER.                     Returns null if neither are found.                  Parameters                     packageName : The name of the package to inspect.                 Returns                     A fully-qualified Intent that can be used to launch the main activity in the                     package. Returns null if the package does not contain such an activity,                     or if packageName is not recognized.             */             // Initialize a new Intent             Intent intent = pm.getLaunchIntentForPackage(packageName);              /*                 public Intent addCategory (String category)                     Add a new category to the intent. Categories provide additional detail about                     the action the intent performs. When resolving an intent, only activities that                     provide all of the requested categories will be used.                  Parameters                     category : The desired category. This can be either one of the predefined                     Intent categories, or a custom category in your own namespace.                 Returns                     Returns the same Intent object, for chaining multiple calls into a single statement.             */             /*                 public static tanggapan String CATEGORY_LAUNCHER                     Should be displayed in the top-level launcher.                      Constant Value: "android.intent.category.LAUNCHER"             */             // Add category to intent             intent.addCategory(Intent.CATEGORY_LAUNCHER);              if(intent == null){                 // Throw PackageManager NameNotFoundException                 throw new PackageManager.NameNotFoundException();             }else{                 // Start the app                 mContext.startActivity(intent);             }         }catch(PackageManager.NameNotFoundException e){             /*                 public static int e (String tag, String msg)                     Send an ERROR log message.                  Parameters                     tag : Used to identify the source of a log message. It usually identifies the                         class or activity where the log call occurs.                     msg : The message you would like logged.             */             // Log the exception             Log.e("Launch",e.getMessage());         }     } }