Question

我正在尝试实现下面的代码，每件事情都可以正常工作这是我面临的情况

mainactivity只有一个按钮来打开splashactivity
splash活动会解析部分打开listactvity
我的工作流程是用户是否点击了主要活动中的按钮它打开启动活动并重定向到listactivty 如果用户单击，则在启动活动时会出现问题 andorid后退按钮它确实回到主要活动但是 splashactivity中的解析继续，用户被重定向到 listactivty这个东西不应该发生，当用户在启动时活动点击了后退按钮它应该回到mainactivity 并留在那里

怎么做呢

package com.site.name;

public class SplashActivity extends Activity {


    RSSFeed feed;
    String fileName;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.splash);

        fileName = "TDRSSFeed.td";
        Intent i = getIntent();
        int position =  i.getExtras().getInt("position");
        String[] country = i.getStringArrayExtra("country");
//      //public String RSSFEEDURL = "http://blogname.blogspot.com//feeds/posts/default/-/Awards?alt=rss";
        Toast.makeText(getApplicationContext(), country[position], Toast.LENGTH_SHORT).show();
        //Toast.makeText(getApplicationContext(), country[position], Toast.LENGTH_SHORT).show();
        File feedFile = getBaseContext().getFileStreamPath(fileName);

        ConnectivityManager conMgr = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
        if (conMgr.getActiveNetworkInfo() == null) {

            // No connectivity. Check if feed File exists
            if (!feedFile.exists()) {

                // No connectivity & Feed file doesn't exist: Show alert to exit
                // & check for connectivity
                AlertDialog.Builder builder = new AlertDialog.Builder(this);
                builder.setMessage(
                        "Unable to reach server, \nPlease check your connectivity.")
                        .setTitle("TD RSS Reader")
                        .setCancelable(false)
                        .setPositiveButton("Exit",
                                new DialogInterface.OnClickListener() {
                                    @Override
                                    public void onClick(DialogInterface dialog,
                                            int id) {
                                        finish();
                                    }
                                });

                AlertDialog alert = builder.create();
                alert.show();
            } else {

                // No connectivty and file exists: Read feed from the File
                Toast toast = Toast.makeText(this,
                        "No connectivity!",
                        Toast.LENGTH_LONG);
                toast.show();
                //feed = ReadFeed(fileName);
                startLisActivity(feed);
            }

        } else {

            // Connected - Start parsing
            new AsyncLoadXMLFeed().execute();

        }

    }

    private void startLisActivity(RSSFeed feed) {


        Bundle bundle = new Bundle();
        bundle.putSerializable("feed", feed);

                // launch List activity
                    Intent intent = new Intent(SplashActivity.this, ListActivity.class);
                    intent.putExtras(bundle);
                    startActivity(intent);
                    overridePendingTransition(R.anim.slide_in, R.anim.slide_out);
                    // kill this activity
                    finish();

    }

    private class AsyncLoadXMLFeed extends AsyncTask<Void, Void, Void> {

        @Override
        protected Void doInBackground(Void... params) {

            // Obtain feed
            DOMParser myParser = new DOMParser();
            Intent i = getIntent();
            int position =  i.getExtras().getInt("position");
            String[] country = i.getStringArrayExtra("country");
            //feed = myParser.parseXml(RSSFEEDURL);
            //feed = myParser.parseXml("http://blogname.blogspot.com//feeds/posts/default/-/Awards?alt=rss");
            feed = myParser.parseXml("http://blogname.blogspot.com//feeds/posts/default/-/" + country[position] + "?alt=rss");
            if (feed != null && feed.getItemCount() > 0)
                WriteFeed(feed);
            return null;

        }

        @Override
        protected void onPostExecute(Void result) {
            super.onPostExecute(result);

            startLisActivity(feed);
        }

    }

    // Method to write the feed to the File
    private void WriteFeed(RSSFeed data) {

        FileOutputStream fOut = null;
        ObjectOutputStream osw = null;

        try {
            fOut = openFileOutput(fileName, MODE_PRIVATE);
            osw = new ObjectOutputStream(fOut);
            osw.writeObject(data);
            osw.flush();
        }

        catch (Exception e) {
            e.printStackTrace();
        }

        finally {
            try {
                fOut.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    @Override
    public void onBackPressed() {
        //Include the code here
        return;
    }

}

Answer 1

您可以取消在MainActivity的onRestart（）中解析Feed，因为这是MainActivity的一种方法，当您从解析活动中按回来时将调用该方法。

您可以阅读有关活动生命周期here的更多信息。

Answer 2

要检测后退按钮按下事件，请使用以下方法

@Override
public void onBackPressed() {
   // do something on back.
   // Change your activity by calling intent
   return;
}

Answer 3

如果您想使用后退按钮执行任何操作，则必须手动覆盖它。

@Override
Public void onBackPressed() {

//do whatever you want to do as your question is quite confusing.    

return;
}

如果按下android后退按钮，请不要打开第二个活动

3 个答案: