How-to articles, tricks, and solutions about JAVA

To append text to the end of an existing file in Java, you can use the Files.write() method from the java.nio.file package. This method allows you to write a sequence of characters to a file in a single operation.

To convert a List to an array in Java, you can use the toArray() method of the List interface. This method returns an array containing all of the elements in the list in the proper order.

There are several ways to iterate over a List in Java. Here are some of the most common approaches:

To convert a comma-separated String to a List in Java, you can use the String.split() method to split the string into an array of substrings, and then use the Arrays.asList() method to create a list from that array.

To check the certificate name and alias in a keystore file, you can use the keytool utility that comes with the Java Development Kit (JDK).

In Java, there are several ways to convert an int value to a String:

String args[] is a parameter in the main method of a Java program. It is an array of strings that can be used to pass command-line arguments to the program when it is executed.

To convert a java.util.Date object to a java.time.LocalDate object, you can use the java.time.Instant class to represent the date as an instant in time, and then use the java.time.LocalDateTime class to convert the instant to a date and time in the local

To find where the JDK is installed on your Windows machine, you can follow these steps:<br>

To check if a Java List contains an object with a specific field value, you can use the List.stream().anyMatch() method along with a lambda expression to filter the elements in the list based on the field value.

If you are getting the "unable to find valid certification path to requested target" error even after importing the certificate, there are a few possible causes and solutions:<br>

To check if a single character appears in a string in Java, you can use the indexOf method of the String class.

This error is usually encountered when trying to parse a JSON string that does not start with a JSON array, but rather a JSON object.

To set the JAVA_HOME environment variable in Linux for all users, you will need to add a line to the /etc/environment file.

To round a number up to two decimal places in Java, you can use the Math.ceil method and multiply the number by 100, then divide the result by 100.

To print colored text to the console using System.out.println, you will need to use special escape sequences in your string to specify the desired color.

To convert a character to its ASCII numeric value in Java, you can use the charAt method of the String class and the intValue method of the Character class.

In Java, both ArrayList and LinkedList are implementations of the List interface that allow you to store a collection of objects in a specific order. However, they are implemented differently and have different performance characteristics.

To download a file from a Spring controller, you can use the ResponseEntity class along with the InputStreamResource class.

To concatenate two arrays in Java, you can use the System.arraycopy method. Here's an example of how you can do this:

To convert a string to a character array in Java, you can use the toCharArray method of the String class. This method returns a new character array that represents the same sequence of characters as the string.

To sort an ArrayList of custom objects by a property, you can use the Collections.sort method and pass it a custom Comparator.

To install Java 8 on macOS, follow these steps:

If you are getting a warning about an SSL connection when connecting to a MySQL database, it may be because you are using an older version of the MySQL client library that does not support SSL connections by default.

You can use the flatMap method from the Stream API to turn a List&lt;List&lt;T&gt;&gt; (a list of lists) into a List&lt;T&gt; in Java 8. Here's an example of how you can do this: