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Articles by Vrundesha Joshi
Page 17 of 22
RTTI (Run-time type Information) in C++
In this section we will see what is the RTTI (Runtime Type Information) in C++. In C++ the RTTI is a mechanism, that exposes information about an object’s datatype during runtime. This feature can be available only when the class has at least one virtual function. It allows the type of an object to be determined when the program is executing.In the following example the first code will not work. It will generate an error like “cannot dynamic_cast base_ptr (of type Base*) to type ‘class Derived*’ (Source type is not polymorphic)”. This error comes because there is no virtual function ...
Read MoreHow to add a primary key constraint to a column of a table in a database using JDBC API?
You can add a primary key constraint to a column of a table using the ALTER TABLE command.SyntaxALTER TABLE table_name ADD CONSTRAINT MyPrimaryKey PRIMARY KEY (column1, column2...);Assume we have a table named Dispatches in the database with 7 columns namely id, CustomerName, DispatchDate, DeliveryTime, Price and, Location with description as shown below:+--------------+--------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------------+--------------+------+-----+---------+-------+ | ProductName | varchar(255) | YES | | NULL | | | CustomerName | varchar(255) | ...
Read MoreHow to drop constraint on a column of a table in a database using JDBC API?
You can drop a constraint on a column of a table using the ALTER TABLE command.SyntaxALTER TABLE table_name DROP CONSTRAINT MyUniqueConstraint;Assume we have a table named Dispatches in the database with 7 columns namely id, CustomerName, DispatchDate, DeliveryTime, Price and, Location with description as shown below:+--------------+--------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------------+--------------+------+-----+---------+-------+ | ProductName | varchar(255) | YES | UNI | NULL | | | CustomerName | varchar(255) | YES | | NULL | ...
Read MoreHow to add custom view in alert dialog?
This example demonstrate about How to add custom view in alert dialogStep 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.Step 2 − Add the following code to res/layout/activity_main.xml. In the above code, we have taken text view.Step 3 − Add the following code to src/MainActivity.javapackage com.example.myapplication; import android.annotation.TargetApi; import android.content.DialogInterface; import android.os.Build; import android.os.Bundle; import android.support.v7.app.AlertDialog; import android.support.v7.app.AppCompatActivity; import android.view.View; import android.widget.EditText; import android.widget.Switch; import android.widget.TextView; import android.widget.Toast; public class MainActivity extends AppCompatActivity { TextView text; @TargetApi(Build.VERSION_CODES.LOLLIPOP) ...
Read MoreHow to get the duplicates values from Arraylist and then get those items in another Arraylist in Android?
This example demonstrate about How to get the duplicates values from Arraylist and then get those items in another Arraylist.Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.Step 2 − Add the following code to res/layout/activity_main.xml. In the above code, we have taken listview to show duplication list items from array list.Step 3 − Add the following code to src/MainActivity.javapackage com.example.andy.myapplication; import android.os.Bundle; import android.support.v7.app.AppCompatActivity; import android.widget.ArrayAdapter; import android.widget.ListView; import java.util.ArrayList; import java.util.HashSet; import java.util.Set; public class MainActivity extends AppCompatActivity ...
Read MoreHow to Add One Side Left Border to TextView in Android using XML?
This example demonstrate about How to Add One Side Left Border to TextView in Android using XML.Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.Step 2 − Add the following code to res/layout/activity_main.xml. In the above code we have taken textview and linear layout. In Linear layout we have added background as text_style. So create a file called text_style.xml in drawable as shown below – ...
Read MoreHow to create our own Listener interface in android?
This example demonstrate about How to create our own Listener interface in androidStep 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.Step 2 − Add the following code to res/layout/activity_main.xml. In the above code, we have taken text view to show listener data.Step 3 − Add the following code to src/MainActivity.javapackage com.example.myapplication; import android.os.Bundle; import android.support.v4.app.FragmentActivity; import android.view.View; import android.widget.TextView; public class MainActivity extends FragmentActivity implements sampleInterFace { sampleInterFace interFace; TextView textView; @Override public void onCreate(Bundle savedInstanceState) ...
Read MoreHow to detect when an Android app goes to the background and come back to the foreground?
This example demonstrate about How to detect when an Android app goes to the background and come back to the foregroundStep 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.Step 2 − Add the following code to res/layout/activity_main.xml. ss In the above code, we have taken text view to show an application status.Step 3 − Add the following code to src/MainActivity.javapackage com.example.myapplication; import android.app.ActivityManager; import android.content.ComponentName; import android.content.Context; import android.os.Bundle; import android.support.v4.app.FragmentActivity; import android.widget.TextView; import java.util.List; public class MainActivity extends FragmentActivity ...
Read MoreHow to clear Singleton instance in android?
Before getting into the example, we should know what singleton design pattern is. A singleton is a design pattern that restricts the instantiation of a class to only one instance. Notable uses include controlling concurrency and creating a central point of access for an application to access its data store.This example demonstrate about How to clear Singleton instance in androidStep 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.Step 2 − Add the following code to res/layout/activity_main.xml. In the above code, we ...
Read MoreHow to handle orientation change android?
This example demonstrate about How to handle orientation change androidStep 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.Step 2 − Add the following code to res/layout/activity_main.xml. In the above code, we have taken text view to show orientation changes.Step 3 − Add the following code to src/MainActivity.javapackage com.example.myapplication; import android.content.res.Configuration; import android.os.Build; import android.os.Bundle; import android.support.annotation.RequiresApi; import android.support.v7.app.AppCompatActivity; import android.widget.TextView; public class MainActivity extends AppCompatActivity { TextView actionEvent; @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP) @Override protected void onCreate(Bundle ...
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