How to go about multiple Buttons and OnClickListeners

I have in 16 Buttons (numbers, plus, minus etc) in my layout XML file.

I'm wondering how to check which button was pressed.

My idea 开发者_如何学编程is, that I will for each button use onClick() method but this method is a bit impractically, because I will have 16 of these onClick() methods one for each Button.

Is there a more elegant way?

You can deal with them all in a single class that implements OnClickListener, or within the activity class if you like...

import android.view.View.OnClickListener;

   public class MyActivity extends Activity implements OnClickListener {

      @Override public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.main);
         Button buttonA = (Button) findViewById(R.id.buttonA);    
         buttonA.setOnClickListener(this);
         Button buttonB = (Button) findViewById(R.id.buttonB); 
         buttonB.setOnClickListener(this);
      }

   //etc... etc...

   public void onClick(View v) {

      switch (v.getId()) {
         case R.id.buttonA: 
          // do something
          break;
         case R.id.buttonB:
          // do something else
          break;
      }
   }

}

You can use one handler that you do not define as anonymous inner class, but in a separate class. onClick() will get the view passed in and you can select from it.

public class MyActivity implements OnClickListener {
    public void onClick(View v) {
       Button b = (Button)v;
       // do what you want 
    }

    ...
}

and then in your layout.xml just put for each button

<Button android:id=".."
        android:onClick="onClick"

Sure. Create an array of your button-ids and assign them the same listener (an implementation of View.OnClickListener - defined as separate class, not as anonymous class) in a loop. In the listener you can check which is the pressed button (by comparing view parameter in onClick() method).

In activity:

MyOnClickListener myListener = new MyOnClickListener();
for (int id : buttonIdArray)
    ((Button)findViewById(id)).setOnClickListener(myListener);

In the onClick method:

int id = view.getId();
switch (id)
{
case ...:
// Do stuff
case ...:
// Do different stuff
}

You don't have to mention 16 on click listeners. Create a one and attach it to each button. onClick() method gets a View as a parameter. This view is your button. Just check for it's id or name.

import android.view.View.OnClickListener;

public class MyActivity extends Activity implements OnClickListener {

  @Override public void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);
     setContentView(R.layout.main);
     Button buttonA = (Button) findViewById(R.id.buttonA);    
     Button buttonB = (Button) findViewById(R.id.buttonB); 
     buttonA.setOnClickListener(this);
     buttonB.setOnClickListener(this);
  }

  public void onClick(View v) {
    if(v==buttonA)
    {
        do something...
    }
    if(v==buttonB)
    {
        do something...
    }
}

I usually do something like this:

@Override
public boolean onTouch(View v, MotionEvent event) 
{
    Button thisButton = (Button) v;


    switch (event.ACTION_DOWN)
    {
        case MotionEvent.ACTION_DOWN:
            for (int i = 0; i < _button.length;i++)

                if (tagOf(thisButton) == tagOf(_button[i]))
                {
                    System.out.println("Button " + i + " pressed!");
                    _textView[i].setText(String.valueOf(_settingBrowser.countUpPosition(i)));
                }
    }
    return false;
}


int tagOf (Button b)
{
    return Integer.parseInt(b.getTag().toString());
}

Initiating the buttons with an ID number at the main class, like this:

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    _button = new Button[FIELDS];


        _button[0] = (Button) findViewById(R.id.Button01);
        _button[1] = (Button) findViewById(R.id.Button02);
        _button[2] = (Button) findViewById(R.id.Button03);
        _button[3] = (Button) findViewById(R.id.Button04);
        _button[4] = (Button) findViewById(R.id.Button05);
        _button[5] = (Button) findViewById(R.id.Button06);


        _padListener = new SettingButtonListener(_button); 

        for (int j = 0; j < _button.length; j++){
            _button[j].setTag(j);
            _button[j].setOnTouchListener(_padListener);

        }
}

This is neat if you have a big number of buttons like you do and want to use the same listener for all of them. Cheers!