Android 将 ArrayList<Model> 从 Activity 传递给 Fragment

Posted 2023-04-15

【中文标题】Android 将 ArrayList<Model> 从 Activity 传递给 Fragment

【英文标题】：Android passing ArrayList<Model> to Fragment from Activity

【发布时间】：2017-02-13 12:53:48

【问题描述】：

您好，我想将数据 ArrayList<Division> 发送到 Fragment 类 ListContentFragment。

在MainActivity 中，我正在进行网络调用以获取数据（JSON），然后对其进行解析以创建ArrayList<Division>，现在我想用收到的数据填充列表视图（现在在@987654326 @)

主活动

 protected void onCreate(Bundle savedInstanceState) 
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        // Adding Toolbar to Main screen
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        // Setting ViewPager for each Tabs
        ViewPager viewPager = (ViewPager) findViewById(R.id.viewpager);
        setupViewPager(viewPager);
        // Set Tabs inside Toolbar
        TabLayout tabs = (TabLayout) findViewById(R.id.tabs);
        tabs.setupWithViewPager(viewPager);
        // Create Navigation drawer and inlfate layout
        NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
        mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer);
        // Adding menu icon to Toolbar
        ActionBar supportActionBar = getSupportActionBar();
        if (supportActionBar != null) 
            VectorDrawableCompat indicator
                    = VectorDrawableCompat.create(getResources(), R.drawable.ic_menu, getTheme());
            indicator.setTint(ResourcesCompat.getColor(getResources(),R.color.white,getTheme()));
            supportActionBar.setHomeAsUpIndicator(indicator);
            supportActionBar.setDisplayHomeAsUpEnabled(true);
        
        // Set behavior of Navigation drawer
        navigationView.setNavigationItemSelectedListener(
                new NavigationView.OnNavigationItemSelectedListener() 
                    // This method will trigger on item Click of navigation menu
                    @Override
                    public boolean onNavigationItemSelected(MenuItem menuItem) 
                        // Set item in checked state
                        menuItem.setChecked(true);

                        // TODO: handle navigation
                        Toast.makeText(MainActivity.this, "Clicked: " + menuItem.getTitle(), Toast.LENGTH_SHORT).show();

                        // Closing drawer on item click
                        mDrawerLayout.closeDrawers();
                        return true;
                    
                );
        // Adding Floating Action Button to bottom right of main view
        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() 
            @Override
            public void onClick(View v) 
                Snackbar.make(v, "Hello Snackbar!",
                        Snackbar.LENGTH_LONG).show();
            
        );

        // Network request test with volley
        NetworkRequests networkRequest = new NetworkRequests(this);
        networkRequest.fetchDummyData();
        divisionList = networkRequest.getDivisions();
    

    // Add Fragments to Tabs
    private void setupViewPager(ViewPager viewPager) 
        Adapter adapter = new Adapter(getSupportFragmentManager());
        adapter.addFragment(new ListContentFragment(), "List");
        adapter.addFragment(new TileContentFragment(), "Tile");
        adapter.addFragment(new CardContentFragment(), "Card");
        viewPager.setAdapter(adapter);
    

Fragment（目前是硬编码，想用 ArrayList 填充）

public class ListContentFragment extends Fragment 

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) 
        RecyclerView recyclerView = (RecyclerView) inflater.inflate(
                R.layout.recycler_view, container, false);
        ContentAdapter adapter = new ContentAdapter(recyclerView.getContext());
        recyclerView.setAdapter(adapter);
        recyclerView.setHasFixedSize(true);
        recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
        return recyclerView;
    

    public static class ViewHolder extends RecyclerView.ViewHolder 
        public ImageView avator;
        public TextView name;
        public TextView description;
        public ViewHolder(LayoutInflater inflater, ViewGroup parent) 
            super(inflater.inflate(R.layout.item_list, parent, false));
            avator = (ImageView) itemView.findViewById(R.id.list_avatar);
            name = (TextView) itemView.findViewById(R.id.list_title);
            description = (TextView) itemView.findViewById(R.id.list_desc);
            itemView.setOnClickListener(new View.OnClickListener() 
                @Override
                public void onClick(View v) 
                    Context context = v.getContext();
                    Intent intent = new Intent(context, DetailActivity.class);
                    intent.putExtra(DetailActivity.EXTRA_POSITION, getAdapterPosition());
                    context.startActivity(intent);
                
            );
        
    

    /**
     * Adapter to display recycler view.
     */
    public static class ContentAdapter extends RecyclerView.Adapter<ViewHolder> 
        // Set numbers of List in RecyclerView.
        private static final int LENGTH = 18;

        private final String[] mPlaces;
        private final String[] mPlaceDesc;
        private final Drawable[] mPlaceAvators;

        public ContentAdapter(Context context) 
            Resources resources = context.getResources();
            mPlaces = resources.getStringArray(R.array.places);
            mPlaceDesc = resources.getStringArray(R.array.place_desc);
            TypedArray a = resources.obtainTypedArray(R.array.place_avator);
            mPlaceAvators = new Drawable[a.length()];
            for (int i = 0; i < mPlaceAvators.length; i++) 
                mPlaceAvators[i] = a.getDrawable(i);
            
            a.recycle();
        
        @Override
        public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) 
            return new ViewHolder(LayoutInflater.from(parent.getContext()), parent);
        

        @Override
        public void onBindViewHolder(ViewHolder holder, int position) 
            holder.avator.setImageDrawable(mPlaceAvators[position % mPlaceAvators.length]);
            holder.name.setText(mPlaces[position % mPlaces.length]);
            holder.description.setText(mPlaceDesc[position % mPlaceDesc.length]);
        

        @Override
        public int getItemCount() 
            return LENGTH;
        
    

【参考方案1】：

如果您想将 ArrayList 传递给片段，则需要确保 Model 类实现 Parcelable。 这里我可以举个例子。

public class ObjectName implements Parcelable 


    public ObjectName(Parcel in) 
        super();
        readFromParcel(in);
    

    public static final Parcelable.Creator<ObjectName> CREATOR = new Parcelable.Creator<ObjectName>() 
        public ObjectName createFromParcel(Parcel in) 
            return new ObjectName(in);
        

        public ObjectName[] newArray(int size) 

            return new ObjectName[size];
        

    ;

    public void readFromParcel(Parcel in) 
        Value1 = in.readInt();
        Value2 = in.readInt();
        Value3 = in.readInt();

    

    public int describeContents() 
        return 0;
    

    public void writeToParcel(Parcel dest, int flags) 
        dest.writeInt(Value1);
        dest.writeInt(Value2);
        dest.writeInt(Value3);
    

然后您可以将ArrayList<ObjectName> 添加到 Bundle 对象。

ArrayList<ObjectName> arraylist = new Arraylist<ObjectName>();  
Bundle bundle = new Bundle();  
bundle.putParcelableArrayList("arraylist", arraylist);
fragment.setArguments(bundle);

在此之后，您可以使用以下方法取回此数据，

Bundle extras = getIntent().getExtras();  
ArrayList<ObjectName> arraylist  = extras.getParcelableArrayList("arraylist");

最后，您可以在片段中显示包含这些数据的列表。希望这将有助于您获得预期的答案。

【讨论】：

谢谢 Alex.. 我会实现的。

【参考方案2】：

我也遇到了同样的问题。 你可以试试这个。 而不是将数组列表作为捆绑包发送到片段。使数组列表被传递，在活动中作为公共和静态的。

public static Arraylist<Division> arraylist;

然后在解析并添加数组列表中的数据后，对片段进行调用。在片段中，您可以将数组列表用作：

ArrayList<Division> list=MainActivity.arraylist;

【讨论】：

有什么缺点？

内存泄漏是产生静态变量或对象的主要原因

如果Activity没有被销毁，那么怎么会发生内存泄漏呢？你能解释一下吗？