java - 如何隐藏Toast消息的显示

Question

我有两个 Activity A Activity 和B Activity ，在B Activity 内部有一个 fragment ，我在其中填充了一个列表BlogRecycleadapter 类中的项目。

当互联网不可用时，在 B Activity 中，它显示“检查互联网”，但是当我按后退按钮并移至 A Activity 时，仍然会出现 toast 消息.

如何隐藏 Toast 消息，使其不出现在第一个 Activity (即 A Activity )上？

我的RecycleViewAdapter类是

BlogRecyclerAdapter.java

package com.nepalpolice.cdp;

import android.annotation.TargetApi;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.Build;
import android.support.annotation.NonNull;
import android.support.v7.widget.RecyclerView;
import android.text.format.DateFormat;
import android.util.Log;
import android.view.KeyEvent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.PopupWindow;
import android.widget.TextView;
import android.widget.Toast;

import com.bumptech.glide.Glide;
import com.bumptech.glide.request.RequestOptions;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.firestore.DocumentSnapshot;
import com.google.firebase.firestore.EventListener;
import com.google.firebase.firestore.FieldValue;
import com.google.firebase.firestore.FirebaseFirestore;
import com.google.firebase.firestore.FirebaseFirestoreException;
import com.google.firebase.firestore.QuerySnapshot;

import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import de.hdodenhof.circleimageview.CircleImageView;

import static com.android.volley.VolleyLog.TAG;
import static com.nepalpolice.cdp.webfaq.isNetworkStatusAvialable;

public class BlogRecyclerAdapter extends RecyclerView.Adapter<BlogRecyclerAdapter.ViewHolder> {

    public List<BlogPost> blog_list;
    public Context context;

    private FirebaseFirestore firebaseFirestore;
    private FirebaseAuth firebaseAuth;
    private PopupWindow popWindow;

    public BlogRecyclerAdapter(List<BlogPost> blog_list){

        this.blog_list = blog_list;


    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.blog_list_item, parent, false);
        context = parent.getContext();
        firebaseFirestore = FirebaseFirestore.getInstance();
        firebaseAuth = FirebaseAuth.getInstance();
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(final ViewHolder holder, int position) {

        holder.setIsRecyclable(false);

        final String blogPostId = blog_list.get(position).BlogPostId;
        final String currentUserId = firebaseAuth.getCurrentUser().getUid();

        String desc_data = blog_list.get(position).getDesc();
        holder.setDescText(desc_data);

        String image_url = blog_list.get(position).getImage_url();
        String thumbUri = blog_list.get(position).getImage_thumb();
        holder.setBlogImage(image_url, thumbUri);

        String user_id = blog_list.get(position).getUser_id();
        //User Data will be retrieved here...



        firebaseFirestore.collection("Users").document(user_id).get().addOnCompleteListener(new OnCompleteListener<DocumentSnapshot>() {
            @Override
            public void onComplete(@NonNull Task<DocumentSnapshot> task) {

                if(task.isSuccessful()){

                    String userName = task.getResult().getString("name");
                    String userImage = task.getResult().getString("image");

                    holder.setUserData(userName, userImage);


                } else {

                    //Firebase Exception

                }

            }
        });

        try {
            long millisecond = blog_list.get(position).getTimestamp().getTime();
            String dateString = DateFormat.format("MM/dd/yyyy", new Date(millisecond)).toString();
            holder.setTime(dateString);
        } catch (Exception e) {

            Toast.makeText(context, "Exception : " + e.getMessage(), Toast.LENGTH_SHORT).show();

        }

        //Get Likes Count
        firebaseFirestore.collection("Posts/" + blogPostId + "/Likes").addSnapshotListener(((Main2Activity) context),new EventListener<QuerySnapshot>() {
            @Override
            public void onEvent(QuerySnapshot documentSnapshots, FirebaseFirestoreException e) {

               if (e!=null) {
                   Log.w(TAG, "listening failed",e);
                   return;
               }

                if(!documentSnapshots.isEmpty()){

                    int count = documentSnapshots.size();

                    holder.updateLikesCount(count);

                } else {

                    holder.updateLikesCount(0);

                }

            }
        });

        if (InternetStatus.getInstance(holder.blogLikeBtn.getContext()).isOnline()) {
            //Get Likes
            firebaseFirestore.collection("Posts/" + blogPostId + "/Likes").document(currentUserId).addSnapshotListener(((Main2Activity) context), new EventListener<DocumentSnapshot>() {
                @Override
                public void onEvent(DocumentSnapshot documentSnapshot, FirebaseFirestoreException e) {

                    if (e != null) {
                        Log.w(TAG, "listening failed", e);
                        return;
                    }

                    if (documentSnapshot.exists()) {

                        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
                            holder.blogLikeBtn.setImageDrawable(context.getDrawable(R.mipmap.action_like_accent));
                        } else {
                            holder.blogLikeBtn.setImageDrawable(context.getResources().getDrawable(R.mipmap.action_like_accent));
                        }
                    } else {

                        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
                            holder.blogLikeBtn.setImageDrawable(context.getDrawable(R.mipmap.action_like_gray));
                        } else {
                            holder.blogLikeBtn.setImageDrawable(context.getResources().getDrawable(R.mipmap.action_like_gray));
                        }
                    }

                }
            });

        }else{

            Toast.makeText(context, "Check Internet", Toast.LENGTH_SHORT).show();
        }
        //Likes Feature

        if (InternetStatus.getInstance(holder.blogLikeBtn.getContext()).isOnline()) {

        holder.blogLikeBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                firebaseFirestore.collection("Posts/" + blogPostId + "/Likes").document(currentUserId).get().addOnCompleteListener(new OnCompleteListener<DocumentSnapshot>() {
                    @Override
                    public void onComplete(@NonNull Task<DocumentSnapshot> task) {

                        if(!task.getResult().exists()){

                            Map<String, Object> likesMap = new HashMap<>();
                            likesMap.put("timestamp", FieldValue.serverTimestamp());

                            firebaseFirestore.collection("Posts/" + blogPostId + "/Likes").document(currentUserId).set(likesMap);

                        } else {

                            firebaseFirestore.collection("Posts/" + blogPostId + "/Likes").document(currentUserId).delete();

                        }

                    }
                });
            }
        });
        }else{

            Toast.makeText(context, "Check Internet", Toast.LENGTH_SHORT).show();
        }


        if (InternetStatus.getInstance(holder.blogCommentBtn.getContext()).isOnline()) {
            holder.blogCommentBtn.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {

                    Intent commentIntent = new Intent(context, CommentsActivity.class);
                    context.startActivity(commentIntent);

                }
            });
        }else{

                Toast.makeText(context, "Check Internet", Toast.LENGTH_SHORT).show();
            }
    }


    @Override
    public int getItemCount() {
        return blog_list.size();
    }

    public class ViewHolder extends RecyclerView.ViewHolder {

        private View mView;

        private TextView descView;
        private ImageView blogImageView;
        private TextView blogDate;

        private TextView blogUserName;
        private CircleImageView blogUserImage;

        private ImageView blogLikeBtn;
        private TextView blogLikeCount;

        private ImageView blogCommentBtn;


        public ViewHolder(View itemView) {
            super(itemView);
            mView = itemView;

            blogLikeBtn = mView.findViewById(R.id.blog_like_btn);
            blogCommentBtn = mView.findViewById(R.id.blog_comment_icon);

        }

        public void setDescText(String descText){

            descView = mView.findViewById(R.id.blog_desc);
            descView.setText(descText);

        }

        public void setBlogImage(String downloadUri, String thumbUri){

            blogImageView = mView.findViewById(R.id.blog_image);

            RequestOptions requestOptions = new RequestOptions();
            requestOptions.placeholder(R.drawable.image_placeholder);

            if (!((Activity) context).isFinishing()) {
                Glide.with(context).applyDefaultRequestOptions(requestOptions).load(downloadUri).thumbnail(
                        Glide.with(context).load(thumbUri)
                ).into(blogImageView);
            }
        }

        public void setTime(String date) {

            blogDate = mView.findViewById(R.id.blog_date);
            blogDate.setText(date);

        }

        public void setUserData(String name, String image) {

            blogUserImage = mView.findViewById(R.id.blog_user_image);
            blogUserName = mView.findViewById(R.id.blog_user_name);

            blogUserName.setText(name);

            RequestOptions placeholderOption = new RequestOptions();
            placeholderOption.placeholder(R.drawable.profile_placeholder);

            if (!((Activity) context).isFinishing()) {
                Glide.with(context).applyDefaultRequestOptions(placeholderOption).load(image).into(blogUserImage);

            }
        }
        public void updateLikesCount(int count){

            blogLikeCount = mView.findViewById(R.id.blog_like_count);
            blogLikeCount.setText(count + " Likes");

        }

    }

}

我的 MainActivity 类是

package com.nepalpolice.cdp;


import android.app.Dialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.SharedPreferences;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;

import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.AlertDialog;
import android.view.LayoutInflater;
import android.view.View;
import android.support.design.widget.NavigationView;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.widget.ImageView;


public class MainActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener  {
    final Context context = this;
    private boolean exit = false;
    Dialog dialog;
    private Menu mymenu;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);



        Fragment fragment = new main();
        getSupportFragmentManager().beginTransaction()
                .replace(R.id.fragment_frame, fragment, fragment.getClass().getSimpleName()).addToBackStack(null).commit();




        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        drawer.setDrawerListener(toggle);
        toggle.syncState();

//Create Dialog


        NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);
    }



    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        mymenu = menu;
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch(item.getItemId()) {
            case R.id.action_refresh:
                Intent intent = new Intent(MainActivity.this, UpdateService.class);
                startService(intent);
                LayoutInflater inflater = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                ImageView iv = (ImageView)inflater.inflate(R.layout.iv_refresh, null);
                Animation rotation = AnimationUtils.loadAnimation(this, R.anim.rotate_refresh);
                rotation.setRepeatCount(Animation.INFINITE);
                iv.startAnimation(rotation);
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
                    item.setActionView(iv);
                }
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.CUPCAKE) {
                    new UpdateTask(this).execute();
                }
                return true;
        }
        return super.onOptionsItemSelected(item);
    }


    public void resetUpdating()
    {
        // Get our refresh item from the menu
        MenuItem m = mymenu.findItem(R.id.action_refresh);
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
            if(m.getActionView()!=null)
            {
                // Remove the animation.
                m.getActionView().clearAnimation();
                m.setActionView(null);
            }
        }
    }


    @SuppressWarnings("StatementWithEmptyBody")
    @Override
    public boolean onNavigationItemSelected(MenuItem item) {
        // Handle navigation view item clicks here.
        int id = item.getItemId();

        if (id == R.id.store) {
            String url = "https://play.google.com/store/apps/developer?id=Sagar%20Rawal&hl=en";
            Intent i = new Intent(Intent.ACTION_VIEW);
            i.setData(Uri.parse(url));
            startActivity(i);
        } else if (id == R.id.contact) {
            Intent activity_about = new Intent(this, profile.class);
            startActivity(activity_about);

        }


        else if (id == R.id.tetris) {
            Intent activity_about = new Intent(this, MenuActivity.class);
            startActivity(activity_about);

        }


        else if (id == R.id.tictac) {
            Intent activity_about = new Intent(this, MainMenuScreen.class);
            startActivity(activity_about);

        }


        else if (id == R.id.home) {
            main fragment = new main();
            FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
            fragmentTransaction.replace(R.id.fragment_frame, fragment, "Main");
            fragmentTransaction.commit();
            fragmentTransaction.addToBackStack(null);


        }
         else if (id == R.id.email) {
            Intent activity_about = new Intent(this, Sendemail.class);
            startActivity(activity_about);
        } else if (id == R.id.call) {
            Intent intent = new Intent(Intent.ACTION_DIAL);
            intent.setData(Uri.parse("tel:+9779868336847"));
            startActivity(intent);

        } else if (id == R.id.share) {
            Intent intent = new Intent(android.content.Intent.ACTION_SEND);
            intent.setType("text/pl" +
                    "ain");
            String shareBodyText = "Your shearing message goes here";
            intent.putExtra(android.content.Intent.EXTRA_SUBJECT, "Subject/Title");
            intent.putExtra(android.content.Intent.EXTRA_TEXT, shareBodyText);
            startActivity(Intent.createChooser(intent, "Share Via"));
        } else if (id == R.id.rate) {
            try {
                startActivity(new Intent(Intent.ACTION_VIEW,
                        Uri.parse("market://details?id=com.nepalpolice.mnemonics&hl=en" + getPackageName())));
            }
            catch (android.content.ActivityNotFoundException anfe) {
                startActivity(new Intent(Intent.ACTION_VIEW,
                        (Uri.parse("https://play.google.com/store/apps/details?id=com.faraksoch.sagar.eroutine&hl=en"))));
            }
        }

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        drawer.closeDrawer(GravityCompat.START);
        return true;
    }


    @Override
    public void onBackPressed() {
        if (exit)
            new AlertDialog.Builder(this)
                    .setTitle("Really Exit?")
                    .setMessage("Are you sure you want to exit?")
                    .setNegativeButton(android.R.string.no, null)
                    .setPositiveButton(android.R.string.yes, new DialogInterface.OnClickListener() {

                        public void onClick(DialogInterface arg0, int arg1) {
                            // MainActivity.super.onBackPressed();
                            finish();
                            moveTaskToBack(true);
                        }
                    }).create().show();

        else {
            FragmentManager fm = getSupportFragmentManager();
            fm.popBackStack();


            if (getSupportFragmentManager().getBackStackEntryCount() ==1) {
                finish();
            }

            exit = true;
            new Handler().postDelayed(new Runnable() {
                @Override
                public void run() {
                    exit = false;
                }
            }, 800);

        }


    }


}

提前致谢。

Answer 1

发生的情况是，您的 Activity 中有三个地方可以调用它:

InternetStatus.getInstance(holder.blogLikeBtn.getContext()).isOnline()

如果你没有网络，你会调用这行代码三次，并且会创建依次出现的三个toast；一个接一个:

Toast.makeText(context, "Check Internet", Toast.LENGTH_SHORT).show();

您应该尝试合并您的代码，以便 toast 只显示一次。考虑以下代码:

    if (InternetStatus.getInstance(holder.blogLikeBtn.getContext()).isOnline()) {
        //Get Likes
        firebaseFirestore.collection("Posts/" + blogPostId + "/Likes").document(currentUserId).addSnapshotListener(((Main2Activity) context), new EventListener<DocumentSnapshot>() {
            @Override
            public void onEvent(DocumentSnapshot documentSnapshot, FirebaseFirestoreException e) {

                if (e != null) {
                    Log.w(TAG, "listening failed", e);
                    return;
                }

                if (documentSnapshot.exists()) {

                    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
                        holder.blogLikeBtn.setImageDrawable(context.getDrawable(R.mipmap.action_like_accent));
                    } else {
                        holder.blogLikeBtn.setImageDrawable(context.getResources().getDrawable(R.mipmap.action_like_accent));
                    }
                } else {

                    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
                        holder.blogLikeBtn.setImageDrawable(context.getDrawable(R.mipmap.action_like_gray));
                    } else {
                        holder.blogLikeBtn.setImageDrawable(context.getResources().getDrawable(R.mipmap.action_like_gray));
                    }
                }

            }
        });
    holder.blogLikeBtn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            firebaseFirestore.collection("Posts/" + blogPostId + "/Likes").document(currentUserId).get().addOnCompleteListener(new OnCompleteListener<DocumentSnapshot>() {
                @Override
                public void onComplete(@NonNull Task<DocumentSnapshot> task) {

                    if(!task.getResult().exists()){

                        Map<String, Object> likesMap = new HashMap<>();
                        likesMap.put("timestamp", FieldValue.serverTimestamp());

                        firebaseFirestore.collection("Posts/" + blogPostId + "/Likes").document(currentUserId).set(likesMap);

                    } else {

                        firebaseFirestore.collection("Posts/" + blogPostId + "/Likes").document(currentUserId).delete();

                    }

                }
            });
        }
    });
        holder.blogCommentBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                Intent commentIntent = new Intent(context, CommentsActivity.class);
                context.startActivity(commentIntent);

            }
        });
    }else{

            Toast.makeText(context, "Check Internet", Toast.LENGTH_SHORT).show();
        }
}