Multiple Buttons' OnClickListener() android

I'm currently making a simple calculator app on Android. Im trying to set up the code so that when a number button is pressed it updates the calculator screen with that number. Currently I'm doing it like this.

    Button one = (Button) findViewById(R.id.oneButton);
	one.setOnClickListener(new View.OnClickListener() {
		
		@Override
		public void onClick(View v) {
			TextView output = (TextView) findViewById(R.id.output);
			output.append("1");
		}
	});

It works but I'm writing this same code for every single button on the calculator. As you can imagine it is very redundant. Is there anyway I can write this code in a more efficient way? One that involves not writing this method for every single button?

You Just Simply have to Follow these steps for making it easy...

You don't have to write new onClickListener for Every Button... Just Implement View.OnClickLister to your Activity/Fragment.. it will implement new Method called onClick() for handling onClick Events for Button,TextView` etc.

> 1. Implement OnClickListener() in your Activity/Fragment

public class MainActivity extends Activity implements View.OnClickListener {

}

> 2. Implement onClick() method in your Activity/Fragment

public class MainActivity extends Activity implements View.OnClickListener {
    
    @Override
	protected void onCreate(Bundle savedInstanceState) {
	    super.onCreate(savedInstanceState);
    }
    
    @Override
    public void onClick(View v) {
      // default method for handling onClick Events..
    }
}

> 3. Implement OnClickListener() For Buttons

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    
    setContentView(R.layout.your_layout);
    
    Button one = (Button) findViewById(R.id.oneButton);
    one.setOnClickListener(this); // calling onClick() method
    Button two = (Button) findViewById(R.id.twoButton);
    two.setOnClickListener(this);
    Button three = (Button) findViewById(R.id.threeButton);
    three.setOnClickListener(this);
}

> 4. Find Buttons By Id and Implement Your Code..

@Override
public void onClick(View v) {
    switch (v.getId()) {
        case R.id.oneButton:
            // do your code
            break;
        case R.id.twoButton:
            // do your code
            break;
        case R.id.threeButton:
            // do your code
            break;
        default:
            break;
    }
}

Please refer to this link for more information :

https://androidacademic.blogspot.com/2016/12/multiple-buttons-onclicklistener-android.html (updated)

This will make easier to handle many buttons click events and makes it looks simple to manage it...

You could set the property:

android:onClick="buttonClicked"

in the xml file for each of those buttons, and use this in the java code:

public void buttonClicked(View view) {

	if (view.getId() == R.id.button1) {
        // button1 action
	} else if (view.getId() == R.id.button2) {
		//button2 action
	} else if (view.getId() == R.id.button3) {
        //button3 action
    }

}

Set a Tag on each button to whatever you want to work with, in this case probably an Integer. Then you need only one OnClickListener for all of your buttons:

Button one = (Button) findViewById(R.id.oneButton);
Button two = (Button) findViewById(R.id.twoButton);
one.setTag(new Integer(1));
two.setTag(new Integer(2));

OnClickListener onClickListener = new View.OnClickListener() {

    @Override
    public void onClick(View v) {
        TextView output = (TextView) findViewById(R.id.output);
        output.append(v.getTag());
    }
}

one.setOnClickListener(onClickListener);
two.setOnClickListener(onClickListener);

I created dedicated class that implements View.OnClickListener.

public class ButtonClickListener implements View.OnClickListener {

    @Override
    public void onClick(View v) {
        Toast.makeText(MainActivity.this, "Button Clicked", Toast.LENGTH_SHORT).show();
    }

}

Then, I created an instance of this class in MainActivity

private ButtonClickListener onClickBtnListener = new ButtonClickListener();

and then set onClickListener for button

btn.setOnClickListener(onClickBtnListener);

public class MainActivity extends AppCompatActivity implements OnClickListener  {
    Button  b1,b2;
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        b1= (Button) findViewById(R.id.button);
        b2= (Button) findViewById(R.id.button2);
        b1.setOnClickListener(this);
        b2.setOnClickListener(this);
    }


    @Override
    public void onClick(View v)
    {
        if(v.getId()==R.id.button)
        {
            Intent intent=new Intent(getApplicationContext(),SignIn.class);
            startActivity(intent);
        }
        else if (v.getId()==R.id.button2)
        {
            Intent in=new Intent(getApplicationContext(),SignUpactivity.class);
            startActivity(in);
        }
    }
}

You can use this

    TextView output = (TextView) findViewById(R.id.output);
    one.setOnClickListener(youractivity.this);
    // set the onclicklistener for other buttons also
    
    @Override
    public void onClick(View v) {
      int id = v.getId();
    switch(id) {
    case R.id.oneButton:      
       append("1",output);
       break;
    case R.id.twoButton:
        append("2",output);
       break;
    case R.id.threeButton:
        append("3",output);
       break;
     } 
      }
    
 private void append(String s,TextView t){
  t.setText(s); 
}
  

you can identify the views in your activity in a separate method.

I had a similar issue and what I did is: Create a array of Buttons

Button buttons[] = new Button[10];

Then to implement on click listener and reference xml id's I used a loop like this

for (int i = 0; i < 10; i++) {		
String buttonID = "button" + i;
		int resID = getResources().getIdentifier(buttonID, "id",
				"your package name here");
		buttons[i] = (Button) findViewById(resID);
		buttons[i].setOnClickListener(this);
	}

But calling them up remains same as in Prag's answer point 4. PS- If anybody has a better method to call up all the button's onClick, please do comment.

Implement onClick() method in your Activity/Fragment public class MainActivity extends Activity implements View.OnClickListener {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }

    @Override
    public void onClick(View v) {
 switch (itemId) {

// if you call the fragment with nevigation bar then used.

           case R.id.nav_menu1:
                fragment = new IntroductionFragment();
                break;
           
// if call activity with nevigation bar then used.
          
            case R.id.nav_menu6:
                Intent i = new Intent(MainActivity.this, YoutubeActivity.class);
                startActivity(i);
      // default method for handling onClick Events..
    }
}

public void onClick(View v) {
    int id = v.getId();
    switch (id){
        case R.id.button1:
            //do ur code
            Toast.makeText(this,"This is button 1",Toast.LENGTH_SHORT).show();
            break;
        case R.id.button2:
            Intent intent = new Intent(this,SecondActivity.class);
            Intent.putExtra("key",value);
            startActivity(intent);
            break;
        case R.id.button3:
            //do ur code
            break;
        case R.id.button4:
            //do ur code;
            break;
        default:
            //do ur code;
    }
}

I find that using a long if/else chain (or switch), in addition to the list of findViewById(btn).setOnClickListener(this) is ugly. how about creating new View.OnlickListeners with override, in-line:

findViewById(R.id.signInButton).setOnClickListener(new View.OnClickListener()
    { @Override public void onClick(View v) { signIn(); }});
findViewById(R.id.signOutButton).setOnClickListener(new View.OnClickListener()
    { @Override public void onClick(View v) { signOut(); }});
findViewById(R.id.keyTestButton).setOnClickListener(new View.OnClickListener()
    { @Override public void onClick(View v) { decryptThisTest(); }});
findViewById(R.id.getBkTicksButton).setOnClickListener(new View.OnClickListener()
    { @Override public void onClick(View v) { getBookTickers(); }});
findViewById(R.id.getBalsButton).setOnClickListener(new View.OnClickListener()
    { @Override public void onClick(View v) { getBalances(); }});

No need of if else's or switch, Let's start: In your every Button or whatever it is (I am using ImageView), Add this attribute android:onClick="DoSomeThing"

In your Activity:

public void DoSomeThing(View v){
    ImageView img1= (ImageView) v; //you have to cast the view i.e. if it's button, it must be cast to Button like below line

    Button b1= (Button) v;

    img1.setImageBitmap(imageBitmap); //or anything you want to do with your view, This will work for all

    b1.setText("Some Text");
 

}