如何在android中使用recyclerview和数据库将位置明智的对象数据一个活动传递给另一个活动

【问题标题】：how to pass Position wise object data one activity to another using recyclerview and databse in android如何在android中使用recyclerview和数据库将位置明智的对象数据一个活动传递给另一个活动
【发布时间】：2016-09-28 11:37:11
【问题描述】：

我已经创建了 recycerview，当我按下 + 按钮时，这个 recycerview 显示人物图像、人名和 + 按钮，像 true 一样更改按钮图像。在 recycerview 底部一个按钮后，这个按钮单击所有数据显示下一个活动。 .

我的适配器

public class BuildCustomAdapter extends RecyclerView.Adapter<BuildCustomAdapter.MyViewHolder> implements Filterable {
private List<People> peopleList;
private List<People> peopleListCopy;


private ItemFilter mFilter = new ItemFilter();

public BuildCustomAdapter(List<People> buildList) {
    this.peopleList = buildList;
    this.peopleListCopy = new ArrayList<>();
    peopleListCopy.addAll(buildList);
}

@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View itemView = LayoutInflater.from(parent.getContext())
            .inflate(R.layout.build_list_row, parent, false);

    return new MyViewHolder(itemView);
}

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

    People people = peopleList.get(position);

    byte[] decodedString = Base64.decode(people.getPeopleImage(), Base64.DEFAULT);
    Bitmap decodedByte = BitmapFactory.decodeByteArray(decodedString, 0, decodedString.length);

    holder.ivPeopleImage.setImageBitmap(decodedByte);
    holder.tvPersonName.setText(people.getPeopleName());

    holder.button.setSelected(people.isSelected());
    holder.button.setOnClickListener(new onSelectListener(position));
}

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

@Override
public Filter getFilter() {
    if (mFilter == null) {
        mFilter = new ItemFilter();
    }
    return mFilter;
}

public class MyViewHolder extends RecyclerView.ViewHolder {
    // public ImageView ivPeopleImage;
    public TextView tvPersonName;
    public Button button;
    public CircularImageView ivPeopleImage;

    public MyViewHolder(View itemView) {
        super(itemView);
        ivPeopleImage = (CircularImageView) itemView.findViewById(R.id.ivPerson);
        tvPersonName = (TextView) itemView.findViewById(R.id.tvPersonName);
        button = (Button) itemView.findViewById(R.id.addbn);
    }
}

private class ItemFilter extends Filter {

    protected FilterResults performFiltering(CharSequence constraint) {
        FilterResults results = new FilterResults();
        if (constraint != null && constraint.length() > 0) {
            List<People> filterList = new ArrayList<>();


            for (int i = 0; i < peopleListCopy.size(); i++) {
                if ((peopleListCopy.get(i).getPeopleName().toUpperCase())
                        .contains(constraint.toString().toUpperCase())) {

                    People peopleName = peopleListCopy.get(i);
                    filterList.add(peopleName);
                }
            }
            results.count = filterList.size();
            results.values = filterList;

        } else {
            results.count = peopleListCopy.size();
            results.values = peopleListCopy;
        }
        return results;
    }

    @Override
    protected void publishResults(CharSequence constraint, FilterResults results) {
        peopleList = (List<People>) results.values;
        notifyDataSetChanged();
    }

}

private class onSelectListener implements View.OnClickListener {

    int mPosition;

    public onSelectListener(int position) {
        mPosition = position;
    }

    @Override
    public void onClick(View view) {
        view.setSelected(!view.isSelected());
        People people = peopleList.get(mPosition);
        people.setSelected(!people.isSelected());
        notifyDataSetChanged();
    }
}

活动

public class BulidActivity extends AppCompatActivity {


private List<People> peopleList = new ArrayList<>();
private List<People> peopleListCopy = new ArrayList<>();
private RecyclerView recyclerView;
private BuildCustomAdapter buildCustomAdapter;


protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_bulid);
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);

    BuildData();
    peopleListCopy.addAll(peopleList);

    recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
    buildCustomAdapter = new BuildCustomAdapter(peopleList);
    RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(getApplicationContext());
    recyclerView.setLayoutManager(mLayoutManager);
    recyclerView.setItemAnimator(new DefaultItemAnimator());
    recyclerView.setAdapter(buildCustomAdapter);

    AddTxt();
    BtnBuildNow();
}

private void BtnBuildNow() {

    Button btnnuildnow = (Button) findViewById(R.id.btn_build_now);

    btnnuildnow.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent intent = new Intent(BulidActivity.this, AlertList.class);
            startActivity(intent);

        }
    });

}

private void AddTxt() {
    EditText editTxt = (EditText) findViewById(R.id.etSearch);
    editTxt.setTextColor(Color.WHITE);

    editTxt.setOnTouchListener(new View.OnTouchListener() {
        @Override
        public boolean onTouch(View v, MotionEvent event) {
            v.setFocusable(true);
            v.setFocusableInTouchMode(true);
            return false;
        }
    });

    editTxt.addTextChangedListener(new TextWatcher() {

        public void onTextChanged(CharSequence s, int start, int before, int count) {

            if (s.length() <= 0) {
                peopleList.clear();
                peopleList.addAll(peopleListCopy);
                recyclerView.setAdapter(null);
                buildCustomAdapter = new BuildCustomAdapter(peopleList);
                recyclerView.setAdapter(buildCustomAdapter);
            } else {
                buildCustomAdapter.getFilter().filter(s.toString());
            }
        }

        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int after) {

        }

        @Override
        public void afterTextChanged(Editable s) {

        }
    });
}

private List<People> BuildData() {
    DataBaseHelper db = new DataBaseHelper(getApplicationContext());

    try {
        db.createDataBase();
    } catch (IOException ioe) {
        throw new Error("Unable to create database");
    }

    if (db.open()) {
        peopleList = db.getPeople();
    }
    return peopleList;

}

模型类

public class People  implements Serializable {
private String peopleImage;
private String peopleName;
private boolean selected;


public void setPeopleName(String peopleName) {
    this.peopleName = peopleName;
}

public String getPeopleName() {
    return peopleName;
}

public void setPeopleImage(String peopleImage) {
    this.peopleImage = peopleImage;
}

public String getPeopleImage() {
    return peopleImage;
}

public boolean isSelected() {
    return selected;
}
public void setSelected(boolean selected) {
    this.selected = selected;
}

DatabaseHelper.class

public class DataBaseHelper extends SQLiteOpenHelper {
private static final String DB_PATH = "/data/data/databasename/databases/";
private static final String DB_NAME = "alertme.db";
private final String TABLE_PEOPLE = "people";
private final String TABLE_CATEGORY = "category";
private final String CATEGORY_NAME = "name";
private final String ID = "id";
private final String CATEGORY_ID = "category_id";
private final String PEOPLE_IMAGE = "image";
private final String PEOPLE_NAME = "name";
private SQLiteDatabase myDataBase;

private final Context myContext;

public DataBaseHelper(Context context) {
    super(context, DB_NAME, null, 1);

    this.myContext = context;
}

public void createDataBase() throws IOException {

    boolean dbExist = checkDataBase();
    if (dbExist) {
    } else {

        this.getReadableDatabase();

        try {
            copyDataBase();
        } catch (IOException e) {

            throw new Error("Error copying database");

        }
    }
}

private boolean checkDataBase() {

    SQLiteDatabase checkDB = null;

    try {
        String myPath = DB_PATH + DB_NAME;
        checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);

    } catch (SQLiteException e) {

    }

    if (checkDB != null) {

        checkDB.close();

    }

    return checkDB != null ? true : false;
}

private void copyDataBase() throws IOException {

    InputStream myInput = myContext.getAssets().open(DB_NAME);

    String outFileName = DB_PATH + DB_NAME;

    OutputStream myOutput = new FileOutputStream(outFileName);

    byte[] buffer = new byte[1024];
    int length;
    while ((length = myInput.read(buffer)) > 0) {
        myOutput.write(buffer, 0, length);
    }

    myOutput.flush();
    myOutput.close();
    myInput.close();

}

public boolean open() {
    try {
        String myPath = DB_PATH + DB_NAME;
        myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
        return true;
    } catch (SQLException sqle) {
        myDataBase = null;
        return false;
    }
}


public List<People> getPeople(String category_id) {
    List<People> peoples = new ArrayList<>();
    try {
        SQLiteDatabase db = SQLiteDatabase.openDatabase(DB_PATH + DB_NAME, null, SQLiteDatabase.OPEN_READWRITE);

        Cursor cursor = db.rawQuery("select * from people where category_id = " + category_id, null);

        while (cursor.moveToNext()) {
            String peopleName = cursor.getString(cursor.getColumnIndex(PEOPLE_NAME));
            String peopleImage = cursor.getString(cursor.getColumnIndex(PEOPLE_IMAGE));

            People people = new People();
            people.setPeopleName(peopleName);
            people.setPeopleImage(peopleImage);

            peoples.add(people);
        }

    } catch (Exception e) {
        Log.d("DB", e.getMessage());
    }
    return peoples;
}

public List<Category> getCategory() {
    List<Category> categoryList = new ArrayList<>();
    try {

        String query = " SELECT * FROM " + TABLE_CATEGORY;
        SQLiteDatabase db = SQLiteDatabase.openDatabase(DB_PATH + DB_NAME, null, SQLiteDatabase.OPEN_READWRITE);
        Cursor cursor = db.rawQuery(query, null);
        while (cursor.moveToNext()) {
            int categoryID = cursor.getInt(cursor.getColumnIndex(ID));
            String categoryName = cursor.getString(cursor.getColumnIndex(CATEGORY_NAME));

            Category category = new Category();
            category.setId(categoryID);
            category.setCategoryName(categoryName);

            categoryList.add(category);

        }

    } catch (Exception e) {
        Log.d("DB", e.getMessage());
    }

    return categoryList;
}

@Override
public synchronized void close() {

    if (myDataBase != null)
        myDataBase.close();

    super.close();

}

@Override
public void onCreate(SQLiteDatabase db) {

}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

}

【问题讨论】：

    标签： java android database listview android-recyclerview


    【解决方案1】：

    首先你应该像这样在你的Build模型类中实现Serializable接口：-

    public class Build implements Serializable{
   //Content will be as it is
}

    像这样更改您的 clickListener：-

    holder.button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                build.setSelected(!build.isSelected());
                if (build.isSelected()) {
                    holder.button.setBackgroundResource(R.drawable.selected_true_icon_new);
    Intent intent = new Intent(context, youractivity.class)
    intenet.putExtra("build",build);
    context.startActivity(intent);
                } else
                    holder.button.setBackgroundResource(R.drawable.add_button_icon);
            }
        });

    在onCreate 接收活动的方法中写下这个：-

    Build build = (Build) getIntent().getSerializableExtra("build");

    【讨论】：

    • 我已经尝试了你的代码，但是在这一行的适配器中出现了一些错误，例如 java.lang.NullPointerException Intent intent = new Intent(context, Temp.class);
    • context 可能为空。您是否制作了一个单独的 BuildCustomAdapter 文件，还是在您的 Activity 中？
    • 单独的 BuildCustomAdapter 文件。
    • 在BuildCustomAdapter 文件中传递上下文对象。像这样修改您的BuildCustomAdapter constructor：- public BuildCustomAdapter(List&lt;Build&gt; buildList, Context context) { this.context = context; this.buildList = buildList; this.buildListCopy = new ArrayList&lt;&gt;(); buildListCopy.addAll(buildList); } 在您的BuildCustomAdapter 类中创建一个context，如下所示：- 私有上下文上下文；
    • 在创建BuildCustomAdapter 的对象时也将代码修改为此：- BuildCustomAdapter buildCustomAdapter = new BuildCustomAdapter(buildList, YourActivityName.this);
    【解决方案2】：

    在下面的方法中添加 Intent，

        holder.button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                build.setSelected(!build.isSelected());
                if (build.isSelected()) {
                    holder.button.setBackgroundResource(R.drawable.selected_true_icon_new);
    Intent intent = new Intent(context, youractivity.class)
    intenet.putExtra("key","value");
    context.startActivity(intent);
                } else
                    holder.button.setBackgroundResource(R.drawable.add_button_icon);
            }
        });

    【讨论】：

    • 下一个activity如何获取模型数据？
    • 替换这些行：intenet.putExtra("key",build.getName());
    • 我已经替换了这一行，但是这个数据显示到这个活动中的下一个活动如何显示？
    • holder.imageView.setImageResource(build.getImages()); holder.name.setText(build.getName());
    • 你必须在哪里显示这些数据？？在回收视图中？？
    【解决方案3】：

    您在 ViewHolder 上注册点击事件的巨大错误！你会得到与实际不同的位置，因为当 android 使用 notifyItemMoved 时，不会调用 viewBindHolder 并且你得到了错误的位置。

    在点击监听器实现中，您应该将 Intent 与您的数据一起传递

    【讨论】：

    • 请解释一下我不知道，因为我在 android 上比较新鲜？
    猜你喜欢
    • 1970-01-01
    • 1970-01-01
    • 1970-01-01
    • 2021-01-20
    • 1970-01-01
    • 1970-01-01
    • 1970-01-01
    • 2016-03-11
    • 1970-01-01
    相关资源
    最近更新 更多
    热门标签
    Java Python linux javascript Mysql C# Docker 算法 前端 SpringBoot Redis Vue spring 设计模式 .net core .net kubernetes c++ 数据库 数据结构 大数据 js 机器学习 微服务 Android Go 程序员 面试 JVM ASP.net core 云原生 人工智能 后端 PHP git CSS golang k8s Nginx Django mybatis 深度学习 多线程 React 架构 devops 爬虫 云计算 Spring Boot LeetCode