getActionProvider（）;在Android中返回null

Question

我学习Android，我试图在操作菜单中添加共享项目。我为此提到http://developer.android.com/training/sharing/shareaction.html。但item.getActionProvider（）在语句中返回null mShareActionProvider =（ShareActionProvider）item.getActionProvider （）;。 我想播放名称通过EditText给出的外部目录中的视频文件。 如果我直接传递的意图，那么视频文件播放。所以我相信，有故意 这里没有问题是完整的代码：

package com.example.sampleactivities; 

import java.io.UnsupportedEncodingException; 
import java.net.URLEncoder; 

import android.support.v7.app.ActionBarActivity; 
import android.support.v7.app.ActionBar; 
import android.support.v4.app.Fragment; 
import android.support.v4.view.MenuItemCompat; 
import android.annotation.SuppressLint; 
import android.annotation.TargetApi; 
import android.content.Intent; 
import android.media.MediaPlayer; 
import android.net.Uri; 
import android.os.Bundle; 
import android.os.Environment; 
import android.view.LayoutInflater; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.view.ViewGroup; 
import android.webkit.WebView.FindListener; 
import android.widget.Button; 
import android.widget.EditText; 
import android.widget.ShareActionProvider; 
import android.widget.Toast; 
import android.os.Build; 

public class UriTesting extends ActionBarActivity { 

    public ShareActionProvider actionprovider; 
    private Menu opmenu; 

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

     if (savedInstanceState == null) { 
      getSupportFragmentManager().beginTransaction() 
        .add(R.id.container, new PlaceholderFragment()) 
        .commit(); 
     } 


    } 

    @Override 
    protected void onStart() { 
     // TODO Auto-generated method stub 
     super.onStart(); 

((Button)findViewById(R.id.SubmitForActionButton)).setOnClickListener(new OnClickListener() { 

      @Override 
      public void onClick(View arg0) { 
      UriTesting.this.doshare();}}); 

} 

    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     this.opmenu=menu; 
     // Inflate the menu; this adds items to the action bar if it is present. 
     getMenuInflater().inflate(R.menu.uri_testing, menu); 
     MenuItem item=menu.findItem(R.id.menu_item_share); 

     actionprovider=(ShareActionProvider)item.getActionProvider(); 

     if (actionprovider == null) { 
      Toast.makeText(getApplicationContext(),"action provider is null",Toast.LENGTH_SHORT).show();} 

     return super.onCreateOptionsMenu(menu); 
    } 

    private void doshare() { 

     if(actionprovider==null) 
     { 
     MenuItem item=opmenu.findItem(R.id.menu_item_share); 

     actionprovider=(ShareActionProvider)item.getActionProvider(); 

     if (actionprovider == null) { 
      Toast.makeText(getApplicationContext(),"action provider is null ",Toast.LENGTH_SHORT).show();} 
     } 
     EditText url_edittext=(EditText)findViewById(R.id.urlreadingEditText); 
     String filename=url_edittext.getText().toString(); 

     try { 
      String encodedfilename = URLEncoder.encode(filename,"UTF-8"); 
       String PATH = Environment.getExternalStorageDirectory()+"/Videos/"+encodedfilename.trim().toString(); 
       Uri url=Uri.parse("file://"+PATH); 

      Intent intent=new Intent(); 
      intent.setAction(android.content.Intent.ACTION_VIEW); 
      intent.setType("video/"); 
      intent.setData(url); 



      //intent.setDataAndType(Uri.parse(url.toString()),"audio/"); 



      // Intent chooser=Intent.createChooser(intent, "select any"); 
      // startActivity(intent); 

     Toast.makeText(getApplicationContext(),"sett",Toast.LENGTH_SHORT).show(); 
     if (actionprovider != null) { 
      Toast.makeText(getApplicationContext(),"sett not null",Toast.LENGTH_SHORT).show(); 
      actionprovider.setShareIntent(intent);} 
     } 
     catch(Exception e) 
     { 
      Toast.makeText(getApplicationContext(),e.toString(),Toast.LENGTH_SHORT).show(); 
     } 

    } 
    @Override 
    public boolean onOptionsItemSelected(MenuItem item) { 
     // Handle action bar item clicks here. The action bar will 
     // automatically handle clicks on the Home/Up button, so long 
     // as you specify a parent activity in AndroidManifest.xml. 
     int id = item.getItemId(); 
     if (id == R.id.action_settings) { 
      return true; 
     } 
     if(id==R.id.menu_item_share) 
      doshare(); 
     return super.onOptionsItemSelected(item); 
    } 

这是XML的菜单

<menu xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:app="http://schemas.android.com/apk/res-auto" 
    xmlns:tools="http://schemas.android.com/tools" 
    tools:context="com.example.sampleactivities.UriTesting" > 

    <item 
     android:id="@+id/action_settings" 
     android:orderInCategory="100" 
     android:title="@string/action_settings" 
     app:showAsAction="never"/> 
    <item 
     android:id="@+id/menu_item_share" 

     android:title="share" 
     app:actionProviderClass="android.widget.ShareActionProvider" 

     app:showAsAction="ifRoom"/> 

</menu> 

Answer 1

如果您使用的是ActionBarActivity，则需要使用android.support.v7.widget.ShareActionProvider而不是您正在使用的android.widget.ShareActionProvider。另外，您必须使用MenuItemCompat.getActionProvider()来检索ActionProvider，而不是直接调用getActionProvider()。