Java 如何在android中使用recyclerview和Database将位置相关的对象数据从一个活动传递到另一个活动

我已经创建了recycerview，当我按下+按钮时，此recycerview显示人物图像、人名和+按钮将按钮图像更改为true。recycerview底部一个按钮后，此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();
    }
}

DatabaseHelper.class

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;
}

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) {

}

public类DataBaseHelper扩展了SQLiteOpenHelper{
私有静态最终字符串DB_PATH=“/data/data/databasename/databases/”；
私有静态最终字符串DB_NAME=“alertme.DB”；
私有最终字符串表_PEOPLE=“PEOPLE”；
私有最终字符串表\u CATEGORY=“CATEGORY”；
私有最终字符串类别\u NAME=“NAME”；
私有最终字符串ID=“ID”；
私有最终字符串CATEGORY\u ID=“CATEGORY\u ID”；
私有最终字符串PEOPLE\u IMAGE=“IMAGE”；
私有最终字符串PEOPLE\u NAME=“NAME”；
私有SQLiteDatabase-myDataBase；
私有最终上下文myContext；
公共数据库助手（上下文）{
super（上下文，DB_名称，null，1）；
this.myContext=上下文；
}
public void createDataBase（）引发IOException{
布尔值dbExist=checkDataBase（）；
if（dbExist）{
}否则{
这是.getReadableDatabase（）；
试一试{
copyDataBase（）；
}捕获（IOE异常）{
抛出新错误（“复制数据库时出错”）；
}
}
}
私有布尔校验数据库（）{
SQLiteDatabase checkDB=null；
试一试{
字符串myPath=DB_PATH+DB_NAME；
checkDB=SQLiteDatabase.openDatabase（myPath，null，SQLiteDatabase.OPEN\u READONLY）；
}catch（sqlitee异常）{
}
if（checkDB！=null）{
checkDB.close（）；
}
return checkDB！=null？true:false；
}
私有void copyDataBase（）引发IOException{
InputStream myInput=myContext.getAssets（）.open（DB_NAME）；
字符串outFileName=DB_路径+DB_名称；
OutputStream myOutput=新文件OutputStream（outFileName）；
字节[]缓冲区=新字节[1024]；
整数长度；
而（（长度=myInput.read（缓冲区））>0）{
写入（缓冲区，0，长度）；
}
myOutput.flush（）；
myOutput.close（）；
myInput.close（）；
}
公共布尔开放（）{
试一试{
字符串myPath=DB_PATH+DB_NAME；
myDataBase=SQLiteDatabase.openDatabase（myPath，null，SQLiteDatabase.OPEN\u READWRITE）；
返回true；
}捕获（SQLException sqle）{
myDataBase=null；
返回false；
}
}
公共列表getPeople（字符串类别\u id）{
List people=new ArrayList（）；
试一试{
SQLiteDatabase db=SQLiteDatabase.openDatabase（db\u路径+db\u名称，null，SQLiteDatabase.OPEN\u读写）；
Cursor Cursor=db.rawQuery（“从人员中选择*，其中category_id=“+category_id，null”）；
while（cursor.moveToNext（））{
String peopleName=cursor.getString（cursor.getColumnIndex（人名））；
String peopleImage=cursor.getString（cursor.getColumnIndex（PEOPLE\u IMAGE））；
人=新人（）；
peopleName（peopleName）；
people.setPeopleImage（peopleImage）；
人民。添加（人民）；
}
}捕获（例外e）{
Log.d（“DB”，e.getMessage（））；
}
返回人民；
}
公共列表getCategory（）{
List categoryList=新建ArrayList（）；
试一试{
String query=“SELECT*FROM”+表格\类别；
SQLiteDatabase db=SQLiteDatabase.openDatabase（db\u路径+db\u名称，null，SQLiteDatabase.OPEN\u读写）；
Cursor Cursor=db.rawQuery（查询，空）；
while（cursor.moveToNext（））{
int categoryID=cursor.getInt（cursor.getColumnIndex（ID））；
String categoryName=cursor.getString（cursor.getColumnIndex（CATEGORY_NAME））；
类别=新类别（）；
类别setId（类别ID）；
category.setCategoryName（categoryName）；
类别列表。添加（类别）；
}
}捕获（例外e）{
Log.d（“DB”，e.getMessage（））；
}
返回类别列表；
}
@凌驾
公共同步作废关闭（）{
if（myDataBase！=null）
myDataBase.close（）；
super.close（）；
}
@凌驾
public void onCreate（SQLiteDatabase db）{
}
@凌驾
public void onUpgrade（SQLiteDatabase db，int-oldVersion，int-newVersion）{
}

在下面的方法中添加意图

    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);
            }
        });

---

您注册到ViewHolder上的click事件的巨大错误！您将得到与实际不同的位置，因为当android使用notifyItemMoved时，viewBindHolder将不会被调用，并且您得到了错误的位置

---

在click listener实现中，您应该首先在

构建

模型类中实现

可序列化

接口，如下所示：-

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

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);
            }
        });

按如下方式更改您的clickListener：-

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

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);
            }
        });

在接收活动的

onCreate

方法中写入以下内容：-

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

---

如何在下一个活动中获取模型数据？替换以下行：intenet.putExtra（“key”，build.getName（））；我已经替换了此行，但此数据将显示给本活动中的下一个活动如何显示？holder.imageView.setImageResource（build.getImages（））；holder.name.setText（build.getName（））；您必须在何处显示这些数据？？在循环视图中？？请解释我不知道，因为我在android中有更新鲜的版本？我尝试了您的代码，但在这一行的适配器中出现了一些错误，如java.lang.NullPointerException Intent Intent=new Intent（上下文，Temp.class）；可能是，

上下文

将为空。您是否创建了saparate

BuildCustomAdapter

文件，还是在您的

活动

中？saparate BuildCustomAdapter文件中。然后在

BuildCustomAdapter

文件中传递上下文对象。修改您的

BuildCustomAdapter

构造函数，如下：-

 public BuildCustomAdapter（List buildList，Context Context）{this.Context=Context；this.buildList=buildList；thi