程式小試身手

btn.setOnClickListener(
      new OnClickListener() {          
         @Override
         public void onClick(View v) {
           
            Toast.makeText(
                  InputEx.this, 
                  "click", 
                  Toast.LENGTH_LONG)
                  .show();
         }
        }
 );

另一種

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends Activity implements View.OnClickListener {

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

        //Intialization Button

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

        btn.setOnClickListener(MainActivity.this);
        //Here MainActivity.this is a Current Class Reference (context)
    }

    @Override
    public void onClick(View v) {

        //Your Logic
    }
}