how to call a method in another Activity from Activity

Question

m developing an Android Application in which I have   I ve two classes class A and Class B    In class A   I tried the code Snippets like below      how to call a method in another Activity from Activity       public class FirstActivity extends Activity          public void onCreate Bundle savedInstanceState            super onCreate savedInstanceState           setContentView R layout main2                    public void method                some code            public class SecondActivity extends Activity          public void onCreate Bundle savedInstanceState            super onCreate savedInstanceState            setContentView R layout main2            FirstActivity fact   new FIrstActivity             fact method

User · Answer

Declare a SecondActivity variable in FirstActivity

Like this

public class FirstActivity extends Activity {  

SecondActivity secactivity;

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main2);
  }      

  public void method() {
    // some code

  secactivity.call_method();// 'Method' is Name of the any one method in SecondActivity

  }  
}

Using this format you can call any method from one activity to another.

User · Answer

The startActivityForResult pattern is much better suited for what you re trying to achieve   http   developer android com reference android app Activity html StartingActivities  Try below code  public class MainActivity extends Activity          Button button1         Override       protected void onCreate Bundle savedInstanceState              super onCreate savedInstanceState             setContentView R layout activity main             textView1  TextView findViewById R id textView1             button1  Button findViewById R id button1             button1 setOnClickListener new OnClickListener                    Override               public void onClick View arg0                      Intent intent new Intent MainActivity this SecondActivity class                     startActivityForResult intent  2     Activity is started with requestCode 2                                             Call Back method  to get the Message form other Activity        Override          protected void onActivityResult int requestCode  int resultCode  Intent data                                super onActivityResult requestCode  resultCode  data                          check if the request code is same as what is passed  here it is 2                      if requestCode  2                                                             do the things u wanted                                              SecondActivity class  public class SecondActivity extends Activity          Button button1         Override       protected void onCreate Bundle savedInstanceState              super onCreate savedInstanceState             setContentView R layout activity second                  button1  Button findViewById R id button1                 button1 setOnClickListener new OnClickListener                        Override                   public void onClick View arg0                          String message  hello                          Intent intent new Intent                          intent putExtra  MESSAGE  message                         setResult 2 intent                         finish     finishing activity                                                        Let me know if it helped

User · Answer

Simple  use static       In activity you have the method you want to call   private static String name    Robert         public static String getData         return name      And in your activity where you make the call   private static String name        name   SplashActivity getData

User · Answer

You should not create an instance of the activity class  It is wrong  Activity has ui and lifecycle and activity is started by startActivity intent   You can use startActivityForResult or you can pass the values from one activity to another using intents and do what is required  But it depends on what you intend to do in the method

User · Answer

If you need to call the same method from both Activities why not then use a third object   public class FirstActivity extends Activity           public void onCreate Bundle savedInstanceState            super onCreate savedInstanceState           setContentView R layout main2                        Utility method   used somewhere in FirstActivity    public class Utility        public static void method                      public class SecondActivity extends Activity           public void onCreate Bundle savedInstanceState            super onCreate savedInstanceState           setContentView R layout main2            Utility method               Of course making it static depends on the use case

User · Answer

public class ActivityB extends AppCompatActivity    static Context mContext    Override protected void onCreate Bundle savedInstanceState        super onCreate savedInstanceState       setContentView R layout activity b        try            Bundle bundle   getIntent   getExtras            if  bundle    null                String texto   bundle getString  message                if  texto    null                    code                              catch  Exception e                e printStackTrace                        public static void launch String message            Intent intent   new Intent mContext  ActivityB class           intent putExtra  message   message           mContext startActivity intent             In ActivityA or Service   public class Service extends Service        Override     public IBinder onBind Intent intent            return null              Override     public int onStartCommand Intent intent  int flags  int startId                 String text    Value to send           ActivityB launch text           Log d TAG  text

[android] how to call a method in another Activity from Activity

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