java - 无法在第 42 行中产生静态引用错误

Question

代码是获取联系人列表。但是对于一个错误。请帮我解决。第 42 行的 mContext 返回错误“无法从类型 contextwrapper 对非静态方法 getapplicationcontext() 进行静态引用”。

package com.example.demo;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;

import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.res.AssetFileDescriptor;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.provider.ContactsContract;
import android.widget.ImageButton;

import android.util.Log;
import android.view.View;
  import android.view.View.OnClickListener;

public class MainActivity extends Activity {

ImageButton imageButton;
Context mContext =  getApplicationContext();
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    addListenerOnButton();
    data();
    getVcardString();
}
public static void getVcardString() {   


    String path = null;     
    String vfile = null;; 
     vfile = "Contacts.vcf"; 

    Cursor phones =              mContext.getContentResolver(). query(ContactsContract.     CommonDataKinds.Phone.CONTENT_URI, null,null, null, null);

    phones.moveToFirst();
    Log.i("Number of contacts", "cursorCount" +phones.getCount());  
    for(int i =0;i<phones.getCount();i++)   {       

         String lookupKey = phones.getString(phones.getColumnIndex(ContactsContract.Contacts.LOOKUP_KEY));
         Log.i("lookupKey", " " +lookupKey);
         Uri uri = Uri.withAppendedPath(ContactsContract.Contacts.CONTENT_VCARD_URI, lookupKey);
         AssetFileDescriptor fd;

         try  {
             fd = mContext.getContentResolver().openAssetFileDescriptor(uri, "r");
             FileInputStream fis = fd.createInputStream();
             byte[] buf = new byte[(int) fd.getDeclaredLength()];
             fis.read(buf);
             String VCard = new String(buf);          

             path = Environment.getExternalStorageDirectory().toString() +    File.separator + vfile;
             FileOutputStream mFileOutputStream = new FileOutputStream(path, true);
             mFileOutputStream.write(VCard.toString().getBytes());    

             phones.moveToNext();               

             File filevcf = new File(path);
             Log.i("file", "file" +filevcf);

         }catch(Exception e1) {
             e1.printStackTrace();  
         }
    }       
    Log.i("TAG", "No Contacts in Your Phone");          
}

protected void data() {             
    File filelocation = filevcf ;     
    Intent sharingIntent = new Intent(Intent.ACTION_SEND);
    sharingIntent.setType("vnd.android.cursor.dir/email");      
    sharingIntent.setType("application/x-vcard");       
    sharingIntent.putExtra(Intent.EXTRA_EMAIL, "mail@gmail.com" );       sharingIntent.putExtra(Intent.EXTRA_STREAM,Uri.parse("file://"+filelocation.getAbsolutePath()));
    startActivity(Intent.createChooser(sharingIntent, "Send email"));            
 }  

public void addListenerOnButton() {
    final Context context =   getApplicationContext();


    imageButton = (ImageButton) findViewById(R.id.imageButton1);

    imageButton.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View arg0) {


            Intent intent1 = new Intent(context, secondjav.class);
                        startActivity(intent1);   


        }

    });

  }

}

Answer 1

如果您真的需要您的方法“getVcardString()”保持静态，那么您应该这样做:为您的应用程序创建扩展 android.app.Application 的新类

public class MyApplication extends Application {
   static Context appContext;

   public MyApplication() {
       super();
   }

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

      appContext = getApplicationContext();
   }

   public static Context getContext() {
       return appContext;
   }
}

将 list 中的此属性添加到应用程序标记:

android:name=".MyApplication"

并在您的 getVcardString() 方法中使用 MyApplication 类的静态方法而不是使用 mContext:

MyApplication.getContext()

通过这种方式，您可以在应用程序的任何位置访问应用程序上下文。