使用recyclerview适配器显示从sqlite到recyclerview的数据

时间：2017-12-14 23:48:51

标签： java android sqlite android-recyclerview

我正在创建一个数据库中保存数据的应用程序。我没有使用recyclerview adapter在recyclerview中显示数据。不知道应该编写什么代码。请检查。

这是我的文件：MainActivity.java 

import android.content.Intent;
import android.database.Cursor;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.Menu;
import android.view.MenuItem;

import java.util.ArrayList;


public class MainActivity extends AppCompatActivity {

    private RecyclerView applist;
    ArrayList<Guides> guides;
    GuideAdapter adapter;
    GuideDB guideDB;

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

        guideDB = new GuideDB(this);

        guides = new ArrayList<>();

        applist = (RecyclerView) findViewById(R.id.app_list);
        applist.setHasFixedSize(true);
        applist.setLayoutManager(new LinearLayoutManager(this));
        adapter = new GuideAdapter(this,guides);
        applist.setAdapter(adapter);

        try {
            Cursor cursor = guideDB.getGuides("SELECT * FROM GUIDE_LIST");
            while (cursor.moveToNext()){
                int guide_id = cursor.getInt(0);
                String post_tile = cursor.getString(1);
                String post_desc = cursor.getString(2);
                String post_address = cursor.getString(3);
                byte [] post_image = cursor.getBlob(4);

                Guides g = new Guides(guide_id,post_tile,post_desc,post_address,post_image);
                guides.add(g);}
        }catch (Exception e){e.printStackTrace();}



    }



    @Override
    public boolean onCreateOptionsMenu(Menu menu) {

        getMenuInflater().inflate(R.menu.main_menu,menu);

        return super.onCreateOptionsMenu(menu);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {

        if(item.getItemId() == R.id.action_add){

            startActivity(new Intent(MainActivity.this,PostActivity.class));
        }

        return super.onOptionsItemSelected(item);
    }
}

PostActivity.java 

import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.Toast;

import java.io.ByteArrayOutputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;

public class PostActivity extends AppCompatActivity {

    public ImageButton mSelectImage;
    public EditText mPostTitle;
    public EditText mPostDesc;
    public EditText mPostAddress;
    public Button mSubmitbtn;
    private static final int GALLERY_REQUEST= 1;
    GuideDB guideDB;
    Bitmap bitmap;

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


        guideDB = new GuideDB(this);
        mSelectImage = (ImageButton) findViewById(R.id.imageSelect);
        mPostTitle = (EditText) findViewById(R.id.titleField);
        mPostDesc = (EditText) findViewById(R.id.descField);
        mPostAddress = (EditText) findViewById(R.id.addressField);
        mSubmitbtn = (Button) findViewById(R.id.submitButton);


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

                Intent galleryIntent = new Intent(Intent.ACTION_GET_CONTENT);
                galleryIntent.setType("image/*");
                startActivityForResult(galleryIntent,GALLERY_REQUEST);
            }
        });
        mSubmitbtn.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View view){

                if(!mPostTitle.getText().toString().isEmpty() && !mPostDesc.getText().toString().isEmpty() && !mPostAddress.getText().toString().isEmpty())
                {
                    ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
                    bitmap.compress(Bitmap.CompressFormat.PNG,50,outputStream);
                    byte[] byteArray = outputStream.toByteArray();

                    try {
                        guideDB.addGuide(mPostTitle.getText().toString(),
                                mPostDesc.getText().toString(),
                                mPostAddress.getText().toString(),byteArray
                        );
                        Toast.makeText(getApplicationContext(),"Added successfully!",Toast.LENGTH_LONG).show();
                    }catch (Exception e){e.printStackTrace();}
                }

            }
        });

}


    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if(requestCode == GALLERY_REQUEST && resultCode == RESULT_OK) {

            Uri mimageUri = data.getData();
           try {
               InputStream inputstream = getContentResolver().openInputStream(mimageUri);

               bitmap  = BitmapFactory.decodeStream(inputstream);
               mSelectImage.setImageBitmap(bitmap);

           }catch (FileNotFoundException e){e.printStackTrace();}

        }
    }

}

GuideDB.java 

import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteStatement;

/**
 * Created by 291 on 14.12.2017.
 */

public class GuideDB extends SQLiteOpenHelper {

    private  static final int DATABASE_VERSION= 1;
    private static final String DATABASE_NAME= "guide_db";
    private static final String TABLE_NAME = "GUIDE_LIST";
    private static String GUIDE_ID = "guide_id";
    private static String GUIDE_TITLE = "guide_title";
    private static String GUIDE_DESC = "guide_desc";
    private static String GUIDE_ADDRESS = "guide_address";
    private static String GUIDE_IMG = "guides_image";

    public GuideDB(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        String CREATE_TABLE = "CREATE TABLE" + TABLE_NAME + "("
                + GUIDE_ID + "INTEGER PRIMARY KEY AUTOINCREMENT"
                + GUIDE_TITLE + "TEXT"
                + GUIDE_DESC + "TEXT"
                + GUIDE_ADDRESS + "TEXT"
                + GUIDE_IMG + "BLOB" + ")";
        db.execSQL(CREATE_TABLE);

    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS "+ TABLE_NAME);
        onCreate(db);

    }

    public void addGuide (String title,String desc,String address,byte[] image){
        SQLiteDatabase gdb = getWritableDatabase();

        try
        {
            String sql = "INSERT INTO GUIDE_LIST VALUES(NULL,?,?,?)";
            SQLiteStatement statement = gdb.compileStatement(sql);
            statement.clearBindings();
            statement.bindString(1,title);
            statement.bindString(2,desc);
            statement.bindString(3,address);
            statement.bindBlob(4,image);
            statement.execute();


        }catch (Exception e){e.printStackTrace();}

    }

    public Cursor getGuides(String sql){
        SQLiteDatabase gdb = getReadableDatabase();
        return gdb.rawQuery(sql,null);

    }
}

GuideAdapter.java 

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import java.util.ArrayList;

/**
 * Created by 291 on 14.12.2017.
 */

public  class GuideAdapter extends RecyclerView.Adapter<GuideAdapter.ViewHolder> {
    private Context ctx;
    private ArrayList<Guides> guidelist;

    public GuideAdapter(Context ctx, ArrayList<Guides> guidelist) {
        this.ctx = ctx;
        this.guidelist = guidelist;
    }

    @Override
    public GuideAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view= LayoutInflater.from(parent.getContext()).inflate(R.layout.guide_row,parent,false);
        return new ViewHolder(view);
    }


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

        Guides guides = guidelist.get(position);
        holder.psttitle.setText(guides.getPost_title());
        holder.pstdesc.setText(guides.getPost_desc());
        holder.pstaddres.setText(guides.getPost_address());

        byte [] postimg = guides.getPost_image();
        Bitmap bitmap = BitmapFactory.decodeByteArray(postimg,0,postimg.length);
        holder.pstimg.setImageBitmap(bitmap);


    }

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

    public class ViewHolder extends RecyclerView.ViewHolder{

        public ImageView pstimg;
        public TextView psttitle;
        public TextView pstdesc;
        public TextView pstaddres;
        public int id;


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

            pstimg = (ImageView) itemView.findViewById(R.id.post_image);
            psttitle = (TextView) itemView.findViewById(R.id.post_title);
            pstdesc = (TextView) itemView.findViewById(R.id.post_title);
            pstaddres = (TextView) itemView.findViewById(R.id.post_address);
        }
    }
}

Guides.java 

public class Guides {
    private int guide_id;
    private String post_title,post_desc,post_address;
    private byte [] post_image;



    public Guides(int guide_id, String post_title, String post_desc, String post_address, byte [] post_image) {
        this.guide_id = guide_id;
        this.post_title = post_title;
        this.post_desc = post_desc;
        this.post_address = post_address;
        this.post_image = post_image;


    }

    public int getGuide_id() {
        return guide_id;
    }

    public void setGuide_id(int guide_id) {
        this.guide_id = guide_id;
    }

    public String getPost_title() {
        return post_title;
    }

    public void setPost_title(String post_title) {
        this.post_title = post_title;
    }

    public String getPost_desc() {
        return post_desc;
    }

    public void setPost_desc(String post_desc) {
        this.post_desc = post_desc;
    }

    public String getPost_address() {
        return post_address;
    }

    public void setPost_address(String post_address) {
        this.post_address = post_address;
    }

    public byte[] getPost_image() {
        return post_image;
    }

    public void setPost_image(byte[] post_image) {
        this.post_image = post_image;
    }
}

activity_main.xml中

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.ugurcangursen.guideappsqlite.MainActivity">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/app_list"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:padding="10dp"></android.support.v7.widget.RecyclerView>

</RelativeLayout>

activity_post.xml 

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.ugurcangursen.guideappsqlite.PostActivity">


    <ImageButton
        android:id="@+id/imageSelect"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:adjustViewBounds="true"
        android:background="#00ffffff"
        android:scaleType="centerCrop"
        app:srcCompat="@drawable/add_btn" />

    <EditText
        android:id="@+id/titleField"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/imageSelect"
        android:layout_centerHorizontal="true"
        android:layout_marginLeft="20dp"
        android:layout_marginRight="20dp"
        android:layout_marginTop="20dp"
        android:background="@drawable/input_outline"
        android:hint="Post Title..."
        android:inputType="textPersonName"
        android:padding="10dp"
        android:singleLine="true" />

    <EditText
        android:id="@+id/descField"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/titleField"
        android:layout_centerHorizontal="true"
        android:layout_marginLeft="20dp"
        android:layout_marginRight="20dp"
        android:layout_marginTop="20dp"
        android:background="@drawable/input_outline"
        android:hint="Post Description..."
        android:inputType="textMultiLine"
        android:padding="10dp" />

    <EditText
        android:id="@+id/addressField"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/descField"
        android:layout_centerHorizontal="true"
        android:layout_marginLeft="20dp"
        android:layout_marginRight="20dp"
        android:layout_marginTop="20dp"
        android:background="@drawable/input_outline"
        android:hint="Adres..."
        android:inputType="textMultiLine"
        android:padding="10dp" />

    <Button
        android:id="@+id/submitButton"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:background="@color/colorPrimary"
        android:text="SUBMIT POST"
        android:textColor="@android:color/white" />

</RelativeLayout>

guide_row.xml 

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_margin="20dp"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto">


    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical">

        <ImageView
            android:id="@+id/post_image"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:adjustViewBounds="true"
            android:scaleType="centerCrop"
            app:srcCompat="@drawable/add_btn" />

        <TextView
            android:id="@+id/post_title"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:padding="15dp"
            android:textSize="16dp"
            android:textStyle="bold"
            tools:text="Başlık" />

        <TextView
            android:id="@+id/post_desc"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:padding="15dp"
            tools:text="Açıklama" />

        <TextView
            android:id="@+id/post_address"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:padding="15dp"
            tools:text="Adres" />

    </LinearLayout>

</android.support.v7.widget.CardView>

1 个答案:

答案 0 :(得分：0)

我没有查看您发布的所有代码。但是，您确实使用空源（指南）设置了adpater，因此它不会显示任何内容。

以下版本的onCreate方法可能会导致数据显示

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    guideDB = new GuideDB(this);

    guides = new ArrayList<>();

    applist = (RecyclerView) findViewById(R.id.app_list);
    applist.setHasFixedSize(true);
    applist.setLayoutManager(new LinearLayoutManager(this));
    //adapter = new GuideAdapter(this,guides); //<<<< MOVED
    //applist.setAdapter(adapter);  //<<<< MOVED

    try {
        Cursor cursor = guideDB.getGuides("SELECT * FROM GUIDE_LIST");
        while (cursor.moveToNext()){
            int guide_id = cursor.getInt(0);
            String post_tile = cursor.getString(1);
            String post_desc = cursor.getString(2);
            String post_address = cursor.getString(3);
            byte [] post_image = cursor.getBlob(4);

            Guides g = new Guides(guide_id,post_tile,post_desc,post_address,post_image);
            guides.add(g);}
    }catch (Exception e){e.printStackTrace();}

    adapter = new GuideAdapter(this,guides); //<<<< MOVED
    applist.setAdapter(adapter);  //<<<< MOVED
}
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