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Articles on Trending Technologies
Technical articles with clear explanations and examples
How to find all tables that contains columnA and columnB in MySQL?
To find specific column names, use information_schema.columns Here, I am using Id in place of columnA and Name in place of columnB −mysql> select table_name as TableNameFromWebDatabase -> from information_schema.columns -> where column_name IN ('Id', 'Name') -> group by table_name -> having count(*) = 3;This will produce the following output. Following are the table with columns Id and Name −+--------------------------+ | TableNameFromWebDatabase | +--------------------------+ | student | | distinctdemo | | secondtable | | groupconcatenatedemo ...
Read MoreHow to convert bean to JSON object by excluding some properties using JsonConfig in Java?
The JsonConfig class is a utility class that helps to configure the serialization process. We can convert a bean to a JSON object with few properties that can be excluded using the setExcludes() method of JsonConfig class and pass this JSON config instance to an argument of static method fromObject() of JSONObject.Syntaxpublic void setExcludes(String[] excludes)In the below example, we can convert bean to a JSON object by excluding some of the properties.Exampleimport net.sf.json.JSONObject; import net.sf.json.JsonConfig; public class BeanToJsonExcludeTest { public static void main(String[] args) { Student student = new Student("Raja", "Ramesh", ...
Read MoreMySQL query to count the dates and fetch repeated dates as well
To display the count, use aggregate function COUNT(*). Let us first create a table −mysql> create table DemoTable1321 -> ( -> ArrivalDatetime timestamp -> ); Query OK, 0 rows affected (0.50 sec)ExampleInsert some records in the table using insert command −mysql> insert into DemoTable1321 values(now()); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable1321 values('2019-01-10 12:34:00'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable1321 values('2019-06-12 11:34:00'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable1321 values('2019-06-12 04:50:00'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable1321 values('2019-09-18 10:50:45'); Query OK, 1 ...
Read MoreHow to search dob in a table, which is in the yyyy-mm-dd structure and compare only with a specific yyyy format (year) in MySQL?
For this, use MySQL YEAR() as in the below syntax −select * from yourTableName where year(yourColumnName)=’yourYearValue’;Let us first create a table −mysql> create table DemoTable1322 -> ( -> DOB date -> ); Query OK, 0 rows affected (0.55 sec)ExampleInsert some records in the table using insert command −mysql> insert into DemoTable1322 values('1999-04-12'); Query OK, 1 row affected (0.68 sec) mysql> insert into DemoTable1322 values('2010-12-01'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable1322 values('2015-03-09'); Query OK, 1 row affected (0.25 sec) mysql> insert into DemoTable1322 values('2007-05-24'); Query OK, 1 row affected (0.08 sec)Display all records from the table ...
Read MoreFind the final X and Y when they are Altering under given condition in C++
Consider we have the initial values of two positive integers X and Y. Find the final value of X and Y, such that there will be some alteration as mentioned below −step1 − If X = 0 and Y = 0 then terminate the process, otherwise go to step2step2 − If X >= 2Y, then set X = X – 2Y, and go to step1, otherwise go to step3step3 − If Y >= 2X, then set Y = Y – 2X, and go to step1, otherwise end the process.The number X and Y will be in range [0 and 1018] ...
Read MoreHow to add elements to JSON Object using JSON-lib API in Java?
The JSON-lib is a Java library for serializing and de-serializing java beans, maps, arrays, and collections in JSON format. We can add elements to the JSON object using the element() method of JSONObject class. We need to download all the dependent jars like json-lib.jar, ezmorph.jar, commons-lang.jar, commons-collections.jar, commons-beanutils.jar, and commons-logging.jar and can import net.sf.json package in our java program to execute it.Syntaxpublic JSONObject element(String key, Object value) - put a key/value pair in the JSONObject Exampleimport java.util.Arrays; import net.sf.json.JSONObject; public class JsonAddElementTest { public static void main(String[] args) { JSONObject jsonObj ...
Read MoreHow to serialize and deserialize a JSON using the ExclusionStrategy interface in Java?
The ExclusionStrategy interface can be used to exclude any field during serialization and deserialization. We can provide a custom implementation of the ExclusionStrategy interface and need to register it with GsonBuilder using the setExclusionStrategies() method. It configures Gson to apply a set of exclusion strategies during serialization and deserialization.Syntaxpublic GsonBuilder setExclusionStrategies(ExclusionStrategy... strategies)Exampleimport com.google.gson.*; import com.google.gson.ExclusionStrategy; import com.google.gson.FieldAttributes; public class ExclusionStrategyTest { public static void main(String args[]) throws Exception { Gson gson = new GsonBuilder().setExclusionStrategies(new CustomExclusionStrategy()).create(); Person person = new Person(); ...
Read MoreHow can we update an existing JSON data using javax.json API in Java?
The JsonBuilderFactory interface is a factory to create JsonObjectBuilder instance and JsonObjectBuilder is a builder for creating JsonObject models from scratch. This interface initializes an empty JSON object model and provides methods to add name/value pairs to the object model and to return the resulting object. We can create a JsonObjectBuilder instance that can be used to build JsonObject using the createObjectBuilder() method.SyntaxJsonObjectBuilder createObjectBuilder()In the below example, We can update an existing JSON data with newly added data.Exampleimport java.io.*; import javax.json.*; public class UpdateExistingJsonTest { public static void main(String[] args) throws Exception { ...
Read MoreJSON Schema Support using Jackson in Java?
JSON Schema is a specification for JSON based format for defining the structure of JSON data. The JsonSchema class can provide a contract for what JSON data is required for a given application and how to interact with it. The JsonSchema can define validation, documentation, hyperlink navigation, and interaction control of JSON data. We can generate the JSON schema using the generateSchema() method of JsonSchemaGenerator, this class wraps the JSON schema generation functionality.Syntaxpublic JsonSchema generateSchema(Class type) throws com.fasterxml.jackson.databind.JsonMappingExceptionExampleimport com.fasterxml.jackson.core.JsonProcessingException; import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.module.jsonSchema.JsonSchema; import com.fasterxml.jackson.module.jsonSchema.JsonSchemaGenerator; import java.util.List; public class JSONSchemaTest { public static void main(String[] args) throws ...
Read MoreHow to check if a bluetooth device is connected with Android device?
This example demonstrates how do I check if a Bluetooth device is connected with android device.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. Step 3 − Add the following code to src/MainActivity.javaimport android.bluetooth.BluetoothDevice; import android.content.BroadcastReceiver; import android.content.Context; import android.content.Intent; import android.content.IntentFilter; import android.os.Bundle; import android.widget.Toast; import androidx.appcompat.app.AppCompatActivity; public class MainActivity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); ...
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