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Articles on Trending Technologies
Technical articles with clear explanations and examples
Merge two array fields in MongoDB?
To merge, use $setUnion operator. Let us first create a collection with documents −> db.mergeTwoArrayFieldDemo.insertOne({"NaturalNumbers":[1,2,3,8,10,20,30],"WholeNumbers":[0,1,2,63,78,20,45]}); { "acknowledged" : true, "insertedId" : ObjectId("5cd68e4057806ebf1256f11d") }Following is the query to display all documents from a collection with the help of find() method −> db.mergeTwoArrayFieldDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5cd68e4057806ebf1256f11d"), "NaturalNumbers" : [ 1, 2, 3, 8, 10, 20, 30 ], "WholeNumbers" : [ 0, 1, 2, 63, 78, 20, 45 ] }Following is the query to merge two array field in MongoDB.> db.mergeTwoArrayFieldDemo.aggregate([ { "$project": { "MergedArray": { "$setUnion": [ "$NaturalNumbers", "$WholeNumbers" ] } }} ]);This will produce the following output −{ "_id" : ObjectId("5cd68e4057806ebf1256f11d"), "MergedArray" : [ 0, 1, 2, 3, 8, 10, 20, 30, 45, 63, 78 ] }
Read MoreWhat happens when you add a double value to a String in java?
The “+” operator with a String acts as a concatenation operator.Whenever you add a String value to a double using the “+” operator, both values are concatenated resulting a String object.In-fact adding a double value to String is the easiest way to convert a double value to Strings.Exampleimport java.util.Scanner; public class StringsExample { public static void main(String args[]){ Scanner sc = new Scanner(System.in); System.out.println("Enter a double value: "); double d = sc.nextDouble(); System.out.println("Enter a String value: "); ...
Read MoreHow to convert File into a Stream in Java?
Let’s say we have a file “input.txt” here in the directory E:/ with the following content:Open a file with Bufferedreader. We have taken the above file here which is located at E: directory;BufferedReader buffReader = Files.newBufferedReader(Paths.get("E:\input.txt"), StandardCharsets.UTF_8);Now get the stream of lines from the above file and display:buffReader.lines().forEach(System.out::println);The following is an example to convert File into a Stream in Java:Exampleimport java.io.BufferedReader; import java.nio.charset.StandardCharsets; import java.nio.file.Files; import java.nio.file.Paths; public class Demo { public static void main(String[] argv) throws Exception { BufferedReader buffReader = Files.newBufferedReader(Paths.get("E:\input.txt"), StandardCharsets.UTF_8); System.out.println("Stream of lines..."); buffReader.lines().forEach(System.out::println); } ...
Read MoreHow to set action command to JButton in Java
With set action command, here we are displaying a message in the console on the click of a button.Set the button first:JButton btn = new JButton("Demo Button");Now, set Action Listener to fire when the button is clicked:ActionListener actionListener = new ActionListener() { public void actionPerformed(ActionEvent event) { String str = event.getActionCommand(); System.out.println("Clicked = " + str); } };The following is an example to set action command to JButton:Exampleimport java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.JButton; import javax.swing.JOptionPane; public class SwingDemo { public static void main(final String args[]) { JButton btn ...
Read MoreHow to display multiple notifications in android?
This example demonstrate about How to display multiple notifications 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. Step 3 − Add a sound into raw folderStep 4 − Add the following code to src/MainActivity.javapackage app.tutorialspoint.com.notifyme ; import android.app.NotificationChannel ; import android.app.NotificationManager ; import android.content.ContentResolver ; import android.content.Context ; import android.graphics.Color ; import android.media.AudioAttributes ; import android.net.Uri ; import android.support.v4.app.NotificationCompat ; import android.support.v7.app.AppCompatActivity ; import android.os.Bundle ; import android.view.View ; import ...
Read MoreHow to increment a field in MongoDB?
To increment a field in MongoDB, you can use $inc operator. Let us first create a collection with documents −> db.incrementDemo.insertOne({"PlayerScore":100}); { "acknowledged" : true, "insertedId" : ObjectId("5cc81cdd8f9e6ff3eb0ce44e") } > db.incrementDemo.insertOne({"PlayerScore":290}); { "acknowledged" : true, "insertedId" : ObjectId("5cc81ce28f9e6ff3eb0ce44f") } > db.incrementDemo.insertOne({"PlayerScore":560}); { "acknowledged" : true, "insertedId" : ObjectId("5cc81ce68f9e6ff3eb0ce450") }Following is the query to display all documents from a collection with the help of find() method −> db.incrementDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5cc81cdd8f9e6ff3eb0ce44e"), "PlayerScore" : 100 } { "_id" : ObjectId("5cc81ce28f9e6ff3eb0ce44f"), "PlayerScore" : 290 } { "_id" : ObjectId("5cc81ce68f9e6ff3eb0ce450"), "PlayerScore" : ...
Read MoreTemplate Specialization in C++
In C++, the templates are used to create generalized functions and classes. So we can use any type of data like int, char, float, or some user defined data also using templates.In this section, we will see how to use the template specialization. So now we can define some generalized template for different types of data. And some special template function for special type of data. Let us see some example to get better idea.Example Code#include using namespace std; template void my_function(T x) { cout
Read MoreWhat should be used to implement MySQL LIKE statement in MongoDB?
To get MySQL LIKE statement, use the REGEX in MongoDB. Let us first create a collection with documents −> db.likeInMongoDBDemo.insertOne({"Name" : "Sam"}); { "acknowledged" : true, "insertedId" : ObjectId("5cd6922857806ebf1256f123") } > db.likeInMongoDBDemo.insertOne({"Name" : "John" }); { "acknowledged" : true, "insertedId" : ObjectId("5cd6923157806ebf1256f124") } > db.likeInMongoDBDemo.insertOne({"Name" : "Scott"}); { "acknowledged" : true, "insertedId" : ObjectId("5cd6924557806ebf1256f125") } > db.likeInMongoDBDemo.insertOne({"Name" : "Sean"}); { "acknowledged" : true, "insertedId" : ObjectId("5cd6924f57806ebf1256f126") } > db.likeInMongoDBDemo.insertOne({"Name" : "Samuel"}); { "acknowledged" : true, "insertedId" : ObjectId("5cd6925857806ebf1256f127") }Following is the query to display all documents from a collection with ...
Read MoreDoes Mongo shell treats numbers as float by default.? How can we work it around explicitly?
Yes, Mongo shell treats numbers as float by default. To work it as int or any other type, you need to mention explicitly. You can use NumberInt() for this. The syntax is as follows −var anyVariableName= [NumberInt("yourValue1"), NumberInt("yourValue2"), .....N];Let us implement the above syntax in order to treat numbers as integer only (not float) −> var integerArrayDemo = [NumberInt("50"), NumberInt("60"), NumberInt("70"), NumberInt("90"), NumberInt("40")];Following is the query to display the array value −> printjson(integerArrayDemo);This will produce the following output −[ NumberInt(50), NumberInt(60), NumberInt(70), NumberInt(90), NumberInt(40) ]To display the array value, you can use print() −> ...
Read MoreI want to call JButton doClick() method to simulate a click action in Java
Let us first set a JButton:JButton btn = new JButton("DemoButton");Now, attach action listener:btn.addActionListener(new ClickListener());If you have an ActionListener attached to your button it'll fire when you call the method doClick():btn.doClick();The following is an example to call JButton doClick() method to simulate a click action:Exampleimport java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.JButton; import javax.swing.JOptionPane; public class SwingDemo { public static void main(final String args[]) { JButton btn = new JButton("DemoButton"); btn.addActionListener(new ClickListener()); JOptionPane.showMessageDialog(null, btn); btn.doClick(); } } class ClickListener implements ActionListener { public void actionPerformed(ActionEvent e) { ...
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