You can use the concept of Map Reduce. Let us first create a collection with documents −> db.getAllFieldNamesDemo.insertOne({"StudentFirstName":"David", "StudentAge":23}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd998e9b50a6c6dd317ad90") }Following is the query to display all documents from a collection with the help of find() method −> db.getAllFieldNamesDemo.find();This will produce the ... Read More

Yes, we can enable drag and drop between two text fields in Java. Let us first create two JTextFields and set content in it as shown below −JTextField one = new JTextField(20); one.setText("You can drag!"); JTextField two = new JTextField(20); two.setText("Drag here or there");Now, we will enable and drag and ... Read More

Here we will see what will be the effect of pthread_self() in C. The pthread_self() function is used to get the ID of the current thread. This function can uniquely identify the existing threads. But if there are multiple threads, and one thread is completed, then that id can be ... Read More

This example demonstrate about How to determine if an activity has been called by a Notification 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 ... Read More

Set the selection mode to SINGLE_TREE_SELECTION, if you want only a single tree node to be selected −tree.getSelectionModel().setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION);The following is an example to allow only a single tree node to be selected in a JTree −Examplepackage my; import javax.swing.JFrame; import javax.swing.JTree; import javax.swing.tree.DefaultMutableTreeNode; import javax.swing.tree.TreeSelectionModel; public class SwingDemo {   ... Read More

Use find() with dot notation to perform recursive search. Let us first create a collection with documents −> db.findOperationDemo.insertOne({"ClientDetails":[{"ClientId":101, "ClientName":"Chris"}, {"ClientId":102, "ClientName":"Robert"}]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd9a118b50a6c6dd317ad99") } > db.findOperationDemo.insertOne({"ClientDetails":[{"ClientId":110, "ClientName":"David"}, {"ClientId":112, "ClientName":"Mike"}]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd9a12fb50a6c6dd317ad9a") }Following is the query ... Read More

Use DISTINCT for distinct elements and then length to get the size of array −db.yourCollectionName.distinct('yourFieldName').length;Let us first create a collection with documents −> db.countOrSizeDemo.insertOne({"StudentFirstName":"John"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd304f5b64f4b851c3a13dc") } > db.countOrSizeDemo.insertOne({"StudentFirstName":"David"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd304fab64f4b851c3a13dd") } > db.countOrSizeDemo.insertOne({"StudentFirstName":"David"}); {   ... Read More

Here we will see the Hygienic Macros in C. We know the usage of macros in C. But sometimes, it does not return the desired results because of accidental capture of identifiers.If we see the following code, we can see that it is not working properly.Example#include #define INCREMENT(i) do { ... Read More

Yes, you can use capped parameter along with max size. Following is the syntax −db.createCollection("yourCollectionName", {capped:true, size:yourSizeInBytes, max:howManyRecordsYouWant})Let us first create a collection with capped:true −> db.createCollection("limitTheNumberOfRecordsDemo", {capped:true, size:200024, max:3}) { "ok" : 1 }We will now create a collection with documents −> db.limitTheNumberOfRecordsDemo.insertOne({"ClientName":"James Brown"}); {    "acknowledged" : true, ... Read More

Here we will see how to print numbers in a correct sequence using different threads. Here we will create n number of threads, then synchronize them. The idea is, the first thread will print 1, then second thread will print 2 and so on. When one thread is trying to ... Read More