SqLite CURD Operations

 1. Create Helper Class

public class DatabaseHelper extends SQLiteOpenHelper {  
   public static final String Database_name = "Students.db";  
   public static final String Table_name = "Student_table";  
   public static final String col_id = "Id";  
   public static final String col_name = "name";  
   public static final String col_marks = "marks";  
   public DatabaseHelper(@Nullable Context context) {  
     super(context, Database_name, null, 1);  
   }  
   @Override  
   public void onCreate(SQLiteDatabase db) {  
       db.execSQL("create table " + Table_name +" (Id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT , marks INTEGER)");  
   }  
   @Override  
   public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {  
       sqLiteDatabase.execSQL("DROP TABLE IF EXISTS "+Table_name);  
       onCreate(sqLiteDatabase);  
   }  
 } 

2.  Insert Database


  public boolean insertData(String name,String marks)  
   {  
     SQLiteDatabase db = this.getWritableDatabase();  
     ContentValues cv = new ContentValues();  
     cv.put(col_name,name);  
     cv.put(col_marks,marks);  
     Long result = db.insert(Table_name,null,cv);  
     if(result == -1 )  
     {  
       return false;  
     }  
     else  
     {  
       return true;  
     }  
   }  
 }  


 <EditText  
   android:layout_width="match_parent"  
   android:layout_height="wrap_content"  
   android:id="@+id/name"  
   android:hint="name"  
   />  
   <EditText  
     android:layout_width="match_parent"  
     android:layout_height="wrap_content"  
     android:id="@+id/marks"  
     android:hint="marks"  
     />  
   <Button  
     android:layout_width="wrap_content"  
     android:layout_height="wrap_content"  
     android:text="Insert"  
     android:id="@+id/Button"/>  



public class MainActivity extends AppCompatActivity {  
   DatabaseHelper mydb;  
   EditText etname,etmarks;  
   Button insertbtn;  
   @Override  
   protected void onCreate(Bundle savedInstanceState) {  
     super.onCreate(savedInstanceState);  
     setContentView(R.layout.activity_main);  
     mydb = new DatabaseHelper(this);  
     etname = findViewById(R.id.name);  
     etmarks = findViewById(R.id.marks);  
     insertbtn = findViewById(R.id.Button);  
     insertdata();  
   }  
   public void insertdata()  
   {  
     insertbtn.setOnClickListener(new View.OnClickListener() {  
       @Override  
       public void onClick(View view) {  
         Boolean Inserted = mydb.insertData(etname.getText().toString(),etmarks.getText().toString());  
         if(Inserted)  
         {  
           Toast.makeText(MainActivity.this, "Data is Inserted", Toast.LENGTH_SHORT).show();  
         }  
         else  
         {  
           Toast.makeText(MainActivity.this, "Error Inserting", Toast.LENGTH_SHORT).show();  
         }  
       }  
     });  
   }  
 }  

3. Show Database


   <Button  
     android:layout_width="wrap_content"  
     android:layout_height="wrap_content"  
     android:text="Show"  
     android:id="@+id/show"/>  


public Cursor Showdata()  
   {  
     SQLiteDatabase db = this.getWritableDatabase();  
     Cursor cursor = db.rawQuery("select * from "+Table_name,null);  
     return cursor;  
   }  
 

public void showdata()  
   {  
     showbtn.setOnClickListener(new View.OnClickListener() {  
       @Override  
       public void onClick(View view) {  
         Cursor cursor = mydb.Showdata();  
         if(cursor.getCount() == 0)  
         {  
           message("Error","No data");  
           return;  
         }  
         StringBuffer buffer = new StringBuffer();  
         while(cursor.moveToNext())  
         {  
           buffer.append("Id : " + cursor.getString(0)+"\n")  
               .append("Name : "+ cursor.getString(1)+"\n")  
               .append("marks : "+ cursor.getString(2)+"\n");  
         }  
           message("Data",buffer.toString());  
       }  
     });  
   }  
   public void message(String title,String message)  
   {  
     AlertDialog.Builder builder = new AlertDialog.Builder(this);  
     builder.setCancelable(true);  
     builder.setTitle(title)  
         .setMessage(message)  
         .show();  
   }  
 } 



4. Update database


  <EditText  
     android:layout_width="match_parent"  
     android:layout_height="wrap_content"  
     android:id="@+id/ids"  
     android:hint="id"  
     />  

<Button  
     android:layout_width="wrap_content"  
     android:layout_height="wrap_content"  
     android:text="Update"  
     android:id="@+id/Update"/>  



   public boolean update(String id,String name,String marks)  
   {  
     SQLiteDatabase db = this.getWritableDatabase();  
     ContentValues cv = new ContentValues();  
     cv.put(col_id,id);  
     cv.put(col_name,name);  
     cv.put(col_marks,marks);  
     db.update(Table_name,cv,"Id = ?",new String[] { id });  
     return true;  
   }  
 }  


  public void update()  
   {  
     updatebtn.setOnClickListener(new View.OnClickListener() {  
       @Override  
       public void onClick(View view) {  
         Boolean updated = mydb.update(etid.getText().toString(),etname.getText().toString(),  
             etmarks.getText().toString());  
         if(updated)  
         {  
           Toast.makeText(MainActivity.this, "Updated", Toast.LENGTH_SHORT).show();  
         }  
         else  
         {  
           Toast.makeText(MainActivity.this, "Error in Updating", Toast.LENGTH_SHORT).show();  
         }  
       }  
     });  
   } 



5. Delete Database entry


  <Button  
     android:layout_width="wrap_content"  
     android:layout_height="wrap_content"  
     android:text="Delete"  
     android:id="@+id/delete"/>  

 public Integer delete(String id)  
   {  
     SQLiteDatabase db = this.getWritableDatabase();  
     return db.delete(Table_name,"Id = ?",new String[] {id});  
   }  


 public void delete()  
   {  
     deletebtn.setOnClickListener(new View.OnClickListener() {  
       @Override  
       public void onClick(View view) {  
         Integer delete = mydb.delete(etid.getText().toString());  
         if(delete > 0)  
         {  
           Toast.makeText(MainActivity.this, "Data Deleted", Toast.LENGTH_SHORT).show();  
         }  
         else  
         {  
           Toast.makeText(MainActivity.this, "Data Not Deleted", Toast.LENGTH_SHORT).show();  
         }  
       }  
     });  
   }  


6. List View Display

<ListView  
     android:layout_width="match_parent"  
     android:layout_height="wrap_content"  
     android:id="@+id/Listview"/>  



 ListView lv;  
   ArrayList list = new ArrayList();  
   ArrayAdapter adapter;  

 lv = findViewById(R.id.Listview);  
      
     showlist(); 

 
     lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {  
       @Override  
       public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {  
         Toast.makeText(MainActivity.this, String.valueOf(lv.getAdapter().getItem(i)), Toast.LENGTH_SHORT).show();  
       }  
     });  
   }  


public void showlist()  
   {  
     showbtn.setOnClickListener(new View.OnClickListener() {  
       @Override  
       public void onClick(View view) {  
         list.clear();  
         Cursor cursor = mydb.Showdata();  
         if(cursor.getCount() == 0)  
         {  
           Toast.makeText(MainActivity.this, "No Data", Toast.LENGTH_SHORT).show();  
         }  
         while(cursor.moveToNext())  
         {  
           list.add(cursor.getString(0));  
           list.add(cursor.getString(1));  
           list.add(cursor.getString(2));  
         }  
         adapter = new ArrayAdapter(MainActivity.this,android.R.layout.simple_list_item_1,list);  
         lv.setAdapter(adapter);  
       }  
     });  
   }  
 }  



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