How to pass value from Button click event to another class in Android?

Question

I am trying to write a code in Android to pass a value from a button click to another class. I am getting 0 value in the Log and i am not finding any technique to send the proper value.

Please go through my below code :

Java Code:

MainActivity.java

package com.example.mybuttonvalue;

import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;


public class MainActivity extends Activity 
{

Activity activity;

Context cont;

public static int mysum;

@Override
protected void onCreate(Bundle savedInstanceState)
{

    super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_main);

    Button btn = (Button)findViewById(R.id.btn);

    btn.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) 
        {


            Intent intent = new Intent(MainActivity.this,MySum.class);

            intent.putExtra("key",5);

            startActivityForResult(intent,2); 




        }
    });


}

@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)  
                     {  





                     }  

 } }

MySum.java

 package com.example.mybuttonvalue;

 import android.app.Activity;
 import android.app.Dialog;
 import android.content.Context;
 import android.content.Intent;

 import android.view.View;
 import android.widget.Button;

 public class MySum extends Activity
 {

    Activity activity;

    Context context;

    int value = getIntent().getIntExtra("key",0); // 0 is default vlaue

    public MySum(Activity activity,Context cont)
    {

        this.activity = activity;

        this.context = cont;

    }

    public void check(final int x)
    {



        final Dialog dia = new Dialog(context);

        dia.requestWindowFeature(dia.getWindow().FEATURE_NO_TITLE); 

        dia.setContentView(R.layout.check);

        Button btn = (Button) dia.findViewById(R.id.btn);

        btn.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) 
            {

                 int no = 12+x;

                 myvalue(no);

                 Intent intent= getIntent();  
                  intent.putExtra("result",x);  
                  setResult(2,intent);  

                 dia.dismiss();

            }
        });

        dia.show();



    }

    public String myvalue(int x)
    {

         return String.valueOf(x);

    }

}

Log Report

05-18 23:04:29.603: D/My Value :(10375): 0

This is the above code , how can i get 17 in the Log. I should get the result from MySum class to MainActivity class.

Please let me know , suggest me some good solution.

you declare a static variable in MainActivity.java..ie `public static mysum;` and refer this variable in `Mysum` like `MainActivity.mysum` and assign values to it..This value will be available in MainActivity also... — Lal, May 18 '14 at 17:43

Raghunandan · Answer 1 · 2014-05-18T18:22:53.337

You are instantiating a Activity class public class MySum extends Activity which is wrong

MySum my = new MySum(MainActivity.this,MainActivity.this);

Remove the constructor and the above code.

You need to use intent to pass values between activities. To get value back in MainActivity use startActivityForResult and override onActivityResult and get the value using intent.

Example:

In MainActivity.java

Intent intent = new Intent(MainActivity.this,MySum.class);
intent.putExtra("key",5);
startActivityForResult(intent,2);

Then override onActivityResult

 @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)  
                     {  
                       //get data using intent
                       int result = data.getIntextra("result",0);

                     }  

 }

In MySum.java

int value = getIntent().getIntExtra("key",0); // 0 is default vlaue

Do operation on value

Then to return result

  Intent intent= getIntent();  
  intent.putExtra("result",x);  
  setResult(2,intent);

Edit:

public class MySum extends Activity
{

 @Override
 protectes void onCreate(Bundle savedInstanceState)
  {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.mysumlayout); //set layout for mysum
    int value = getIntent().getIntExtra("key",0);
    check(value);

}
public void check(int x)
{

    final Dialog dia = new Dialog(MySum.this);
    dia.requestWindowFeature(dia.getWindow().FEATURE_NO_TITLE); 
    dia.setContentView(R.layout.check);
    Button btn = (Button) dia.findViewById(R.id.btn);
    btn.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) 
        {

             int no = 12+x;
             dia.dismiss();
             Intent intent= getIntent();  
             intent.putExtra("result",no);  
             setResult(2,intent);  
             finish(); 


        }
    });

    dia.show();
} 
}

Note:

Apart from the above code which is just an example you need not have a Activity at all. All you do is some calculation on a int value which does not require a ui. It could be a normal java class which does just some operation without dialog or any other ui stuff.

can it be considerate a duplicate of http://stackoverflow.com/questions/4186021/how-to-start-new-activity-on-button-click? — Blackbelt, May 18 '14 at 17:45
@blackbelt could be. Vote to close. Anyway i will complete my answer by editing — Raghunandan, May 18 '14 at 17:47
Gettin No Scope error on this Intent intent = new Intent(MainActivity.this,MySum.this); The constructor Intent(MainActivity, MySum) is undefined — Anshuman Pattnaik, May 18 '14 at 17:54
@user2551103 typo error. sorry. its `MySum.class`. MySum must be declared in manifest file — Raghunandan, May 18 '14 at 17:55
NO friend code is not working ... getting NullPointerException on line 18 of MySum.java .... — Anshuman Pattnaik, May 18 '14 at 18:00
@user2551103 this will work provided you do it right. Something on line 18 is null. Post what you have done by editing your post. How do i know what is line 18? — Raghunandan, May 18 '14 at 18:01
@user2551103 you are supposed to ActivityCOntest here `final Dialog dia = new Dialog(MySum.this);` — Raghunandan, May 18 '14 at 18:02
@user2551103 you need to read the docs more.. check the edit — Raghunandan, May 18 '14 at 18:10
@user2551103 still having problem you will find a complete example @ http://www.javatpoint.com/android-startactivityforresult-example — Raghunandan, May 18 '14 at 18:19

How to pass value from Button click event to another class in Android?

1 Answers1