Android onKeyDown 再按一次退出

package com.tz.event;import android.app.Activity;import android.os.Bundle;import android.view.KeyEvent;import android.widget.Toast;public class EventActivity extends Activity {/** Called when the activity is first created. */@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main);}private long lastTime;@Overridepublic boolean onKeyDown(int keyCode, KeyEvent event) {if (keyCode == KeyEvent.KEYCODE_BACK) {if (System.currentTimeMillis() - lastTime <= 2000) {// 退出去// onBackPressed();finish();} else {Toast.makeText(this, "再按一次退出", 1000).show();lastTime = System.currentTimeMillis();}return false;}return super.onKeyDown(keyCode, event);}}