Question

在Wallpaper Adapter中，我开始了一个3秒动画GIF的活动。当它结束时，我把它放回到用户所在的活动壁纸中，但它不会去，因为我需要确切地知道哪个类别。如何保存用户所在的类别，以便在gif消失后可以返回？

壁纸活动：

package org.serie.wallpaper.activities;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.widget.Button;
import android.widget.ProgressBar;

import com.google.android.gms.ads.AdRequest;
import com.google.android.gms.ads.InterstitialAd;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.ValueEventListener;

import org.serie.wallpaper.R;
import org.serie.wallpaper.adapters.WallpapersAdapter;
import org.serie.wallpaper.models.Wallpaper;

import java.util.ArrayList;
import java.util.List;

public class WallpapersActivity extends AppCompatActivity {


    List<Wallpaper> wallpaperList;
    List<Wallpaper> favList;
    RecyclerView recyclerView;
    WallpapersAdapter adapter;

    DatabaseReference dbWallpapers, dbFavs;
    ProgressBar progressBar;

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_wallpapers);

        Intent intent = getIntent();
        final String category = intent.getStringExtra("category");

        Toolbar toolbar = findViewById(R.id.toolbar);
        toolbar.setTitle(category);
        setSupportActionBar(toolbar);

        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        getSupportActionBar().setDisplayShowHomeEnabled(true);

        toolbar.setNavigationOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                startActivity(new         Intent(getApplicationContext(),HomeActivity.class));
            }
        });

        favList = new ArrayList<>();
        wallpaperList = new ArrayList<>();
        recyclerView = findViewById(R.id.recycler_view);
        recyclerView.setHasFixedSize(true);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        adapter = new WallpapersAdapter(this, wallpaperList);

        recyclerView.setAdapter(adapter);

        progressBar = findViewById(R.id.progressbar);
        dbWallpapers = FirebaseDatabase.getInstance().getReference("images")
                .child(category);


        if (FirebaseAuth.getInstance().getCurrentUser() != null) {
            dbFavs = FirebaseDatabase.getInstance().getReference("users")
                    .child(FirebaseAuth.getInstance().getCurrentUser().getUid())
                    .child("favourites")
                    .child(category);
            fetchFavWallpapers(category);
        } else {
            fetchWallpapers(category);
        }

    }

    private void fetchFavWallpapers(final String category) {
        progressBar.setVisibility(View.VISIBLE);
        dbFavs.addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                progressBar.setVisibility(View.GONE);
                if (dataSnapshot.exists()) {
                    for (DataSnapshot wallpaperSnapshot : dataSnapshot.getChildren()) {

                        String id = wallpaperSnapshot.getKey();
                        String title = wallpaperSnapshot.child("title").getValue(String.class);
                        String desc = wallpaperSnapshot.child("desc").getValue(String.class);
                        String url = wallpaperSnapshot.child("url").getValue(String.class);

                        Wallpaper w = new Wallpaper(id, title, desc, url, category);
                        favList.add(w);
                    }
                }
                fetchWallpapers(category);
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        });
    }

    private void fetchWallpapers(final String category) {
        progressBar.setVisibility(View.VISIBLE);
        dbWallpapers.addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                progressBar.setVisibility(View.GONE);
                if (dataSnapshot.exists()) {
                    for (DataSnapshot wallpaperSnapshot : dataSnapshot.getChildren()) {

                        String id = wallpaperSnapshot.getKey();
                        String title = wallpaperSnapshot.child("title").getValue(String.class);
                        String desc = wallpaperSnapshot.child("desc").getValue(String.class);
                        String url = wallpaperSnapshot.child("url").getValue(String.class);

                        Wallpaper w = new Wallpaper(id, title, desc, url, category);

                        if (isFavourite(w)) {
                            w.isFavourite = true;
                        }

                        wallpaperList.add(w);
                    }
                    adapter.notifyDataSetChanged();
                }
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        });
    }

    private boolean isFavourite(Wallpaper w) {
        for (Wallpaper f : favList) {
            if (f.id.equals(w.id)) {
                return true;
            }
        }
        return false;
    }
}

下载Gif活动：

package org.serie.wallpaper.activities;

import android.app.Activity;

import android.content.Context;

import android.content.Intent;
import android.os.Bundle;

import org.serie.wallpaper.R;

import org.serie.wallpaper.models.Category;

import java.util.List;

public class Downloadgif extends Activity {

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

        Thread timer = new Thread(){

            public void run(){
                try{
                    sleep(5000);   // set the duration of splash screen
                }
                catch(InterruptedException e){
                    e.printStackTrace();
                } finally {

                    Intent intent = new Intent(Downloadgif.this, WallpapersActivity.class);
                    startActivity(intent);

                }
            }
        };
        timer.start();
    }

    @Override
    protected void onPause() {
        super.onPause();
        finish();
    }
}

这是用户点击类别时：

@Override
    public void onClick(View view) {

        if (mInterstitialAd.isLoaded()) {
            mInterstitialAd.show();
        } else {
            mInterstitialAd.loadAd(new AdRequest.Builder().build());
        }

        int p = getAdapterPosition();
        Category c = categoryList.get(p);

        Intent intent = new Intent(mCtx, WallpapersActivity.class);
        intent.putExtra("category", c.name);

        mCtx.startActivity(intent);
    }

糟糕：抱歉英语

Answer 1

您可以使用sharedPreferences。

SharedPreferences sharedPreferences;

进入onCreate：

sharedPreferences = getSharedPreferences("prefs", Context.MODE_PRIVATE);

SharedPreferences.Editor editor = sharedPreferences.edit();

现在您可以使用以下方式存储信息：

editor.putString("example_key", "example string to store");
editor.commit();

检查：

editor.getString("example_key", "");

您也可以使用相同但使用布尔值：

editor.putBoolean("example_key", true);
editor.commit(); //Never forget the commit when you use a put

editor.getBoolean("example_key"), true); // To get the value. The second parameter is required but is a default one

如何保存最后一类壁纸

1 个答案: