Android setOnClickListener method - How does it work?

Solution 1:

It works like this. View.OnClickListenere is defined -

public interface OnClickListener {
    void onClick(View v);
}

As far as we know you cannot instantiate an object OnClickListener, as it doesn't have a method implemented. So there are two ways you can go by - you can implement this interface which will override onClick method like this:

public class MyListener implements View.OnClickListener {
    @Override
    public void onClick (View v) {
         // your code here;
    }
}

But it's tedious to do it each time as you want to set a click listener. So in order to avoid this you can provide the implementation for the method on spot, just like in an example you gave.

setOnClickListener takes View.OnClickListener as its parameter.

Solution 2:

This is the best way to implement Onclicklistener for many buttons in a row implement View.onclicklistener.

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

This is a button in the MainActivity

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    bt_submit = (Button) findViewById(R.id.submit);

    bt_submit.setOnClickListener(this);
}

This is an override method

    @Override
    public void onClick(View view) {
        switch (view.getId()){
            case R.id.submit:
                //action

                break;

            case R.id.secondbutton:
                //action
                break;
        }
    }