问如何取消吐司

EN

    final Toast toast = Toast.makeText(ctx, "This message will disappear in 1 second", Toast.LENGTH_SHORT);
    toast.show();

    Handler handler = new Handler();
        handler.postDelayed(new Runnable() {
           @Override
           public void run() {
               toast.cancel(); 
           }
    }, 1000); //specify delay here that is shorter than Toast.LENGTH_SHORT

package co.toast;

import android.annotation.SuppressLint;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;

public class ShowToastActivity extends Activity {
    private Toast toast = null;
    Button btnShowToast;

    @SuppressLint("ShowToast")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        // creates only one toast object..
        toast = Toast.makeText(getApplicationContext(), "", Toast.LENGTH_LONG);

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

        btnShowToast.setOnClickListener(new OnClickListener() {

             @Override
             public void onClick(View v) {

                // only set text to toast object..
                toast.setText("My toast!");
                toast.show();
            }
        });
    }

    @Override
    protected void onDestroy() 
    {
        toast.cancel();
        super.onDestroy();
    }

    @Override
    protected void onStop () {
        super.onStop();
        toast.cancel();
    }
}