Android studio mobile development creates a new database and obtains picture and text data from the database to display on the listview list

Android Mobile development Create a new database and get pictures from the database , Text data is displayed in Listview On the list

Ideas :
1. New database ( There are many ways , I borrow it here SQLiteExpert Visual database is built ) And add the corresponding fields to get .db file
2. Query the data we want in the database ( Write your own class NewDao Static method query in )
3. Show in control view On ( Through the adapter listview The contents of the are displayed , Rewrite the adapter getView Method use ” tyre pump ”inflate To fill in listview.)
1.1
Build the following database as shown in the figure List And table actor

img ( I have to pay attention here. I have been doing it for a long time ) Type use blob type , Then click load Import the picture and click again ok The picture is put into the table .

Open after running the simulator Database Management view found data/data/ Project name /database adopt update Add in or replace as shown in the figure

1.2 You can also create a new Mydatahelp To inherit SQLiteOpenHelper Create new databases and tables

package com.example.android_autolist;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import androidx.annotation.Nullable;
public class Mydatahelp extends SQLiteOpenHelper {
    
    public Mydatahelp( Context context, String name,  SQLiteDatabase.CursorFactory factory, int version) {
    
        super(context, name, factory, version);
    }
    @Override
   // new table 
    public void onCreate(SQLiteDatabase db) {
    
        //id,tile, text , img Corresponding to the database 
        String sql =("create table actor(id integer primary key autoincrement,title varchar(20),text varchar(50),img blob )");
        db.execSQL(sql);
          }
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    

    }
}

2.1 In the query database, create a new class to compare with the fields in the database ( What I built is Actor) To store the data obtained from the database
package com.example.android_autolist;
/*
Create a time period type relative to the database

• */

public class Actor {
    
    private  Integer id;
    private  String title;
    private  String text;
    private  byte[] img;
    public byte[] getImg() {
           return img;    }
    public void setImg(byte[] img) {
            this.img = img;    }
    public Integer getId() {
            return id;    }
    public void setId(Integer id) {
            this.id = id;    }
    public String getTitle() {
            return title;    }
    public void setTitle(String title) {
            this.title = title;    }
    public String getText() {
            return text;    }
    public void setText(String text) {
            this.text = text;    }
}

2.2 Query the database , The class being written NewDao Static in getList In the method

 package com.example.android_autolist;
import android.app.blob.BlobHandle;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import java.util.ArrayList;
import java.util.List;
// Query to get database tables actor Chinese content 
public class NewDao {
    
    public  static List<Actor> getList(SQLiteDatabase db){
    
        List<Actor> newActors=new ArrayList<>();
        Cursor cursor=db.query("actor",new String[]{
    "title","text","img"},null,null,null,null,null);
        if(cursor.moveToFirst()){
    
            Actor actor=null;
            do {
    
                actor=new Actor();
                String title=cursor.getString(0);
                actor.setTitle(title);
                String text=cursor.getString(cursor.getColumnIndex("text"));
                actor.setText(text);
                byte[] img = cursor.getBlob(2);
                actor.setImg(img);
                 // Add to list newActors in 
                newActors.add(actor);
            }
            while (cursor.moveToNext());
        }
        return  newActors;
    }

}

Besides :
Layout There should be multiple views in the xml file activity_main.xml and layout.xml file .activity_main.xml Must have Listview Control
activity_main.xml In the code :

<?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=".MainActivity">
    <ListView android:id="@+id/listView1" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_alignParentLeft="true" />

layout.xml In the code

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent">
    <ImageView android:id="@+id/img" android:layout_width="145dp" android:layout_height="110dp" />
    <TextView android:id="@+id/title" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_toRightOf="@+id/img" android:textSize="18dp" android:singleLine="true" android:textColor="#000000" />
    <TextView android:id="@+id/text" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_below="@+id/title" android:layout_toRightOf="@id/img" android:textSize="14dp" />

</RelativeLayout>

3. Now the preparatory work is finished, and the rest is in MainActivity Write the main logic code to call the above classes and controls

package com.example.android_autolist;
import androidx.appcompat.app.AppCompatActivity;
import android.database.sqlite.SQLiteDatabase;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
import java.util.List;
public class MainActivity extends AppCompatActivity {
    
    private ListView listView;
    List <Actor> actors=null;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
    
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //1. New database  2. Query the database information  3. Displayed in the view On 
        Mydatahelp openHelper=new Mydatahelp(this,"List.db",null,1);
        SQLiteDatabase database=openHelper.getWritableDatabase();
        //2. adopt NewDao Static method query in 
        actors=NewDao.getList(database);
         //3. Show 
        listView=findViewById(R.id.listView1);
        // Through the adapter listview The contents of the are displayed 
        listView.setAdapter(new MyAdapter());
}
// newly build MyAdapter  Method 
    public class  MyAdapter extends BaseAdapter{
    
        @Override
        public int getCount() {
    
            //  Get the number of lists dynamically , Determine the number of displays ( When I write two pieces of information in the database, two lists will be displayed )
            return actors.size();
        }
        @Override
        public Object getItem(int position) {
    
            return null;
        }

        @Override
        public long getItemId(int position) {
    
            return 0;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
    
           View view;
           if (convertView==null)
           {
        // tyre pump   obtain xml  The definition of view
               LayoutInflater inflater= (LayoutInflater) getSystemService(LAYOUT_INFLATER_SERVICE);
               view =inflater.inflate(R.layout.layout,null);
           }
           else  view=convertView;
           // Find control 
            TextView title=view.findViewById(R.id.title);
            TextView text=view.findViewById(R.id.text);
            ImageView imageView=view.findViewById(R.id.img);
            // important 
            // Get the data of the current item 
            Actor actor=actors.get(position);
            // Set text 
            title.setText(actor.getTitle());
            text.setText(actor.getText());
            // Convert a byte array to bitmap Type in order to Listview It shows that 
            Bitmap bitmap=stringToBitmap(actor.getImg());
            imageView.setImageBitmap(bitmap);
            return view;
        }
    }
    // Byte stream value   convert to bitmap In order to call imageView.setImageBitmap() To show pictures 
    public Bitmap stringToBitmap(byte[] bytes) {
    
        return BitmapFactory.decodeByteArray(bytes, 0, bytes.length);
    }
}

Final effect :

I hope this article will help you , The code may have shortcomings , I would like to discuss with you .
See the following link for the overall project package :
https://download.csdn.net/download/weixin_46097122/16138055