How-to articles, tricks, and solutions about JAVA

To convert a String to a UTF-8 encoded byte array in Java, you can use the getBytes method of the String class and specify the character encoding as "UTF-8".

To convert a JSON string to a Java object, you can use the fromJson method of the Gson class.

In Java, you can convert a string to a character using the charAt() method of the String class. This method takes an index as an argument and returns the character at that index.

To count the number of occurrences of an element in a List in Java, you can use the Collections.frequency(Collection, Object) method, which returns the number of times the specified element appears in the collection.

To create a directory in Java, you can use the mkdir() method of the File class.

Learn 3 ways of creating files in Java with examples. Use java.io.File class, java.io.FileOutputStream class or Java NIO Files.write() class for creating new files in Java.

In Java, it is not possible to create a generic array directly. However, you can create an array of a specific type and then cast it to a generic type.

There are a few different ways to create a subarray from another array in Java:

To create a temporary directory/folder in Java, you can use the createTempDirectory() method of the Files class in the java.nio.file package.

To create a two-dimensional array in Java, you can use the following syntax:

To create an ArrayList from an array in Java, you can use the ArrayList constructor that takes an Collection as an argument.

To create a JSON array using JSONObject in Java, you can use the put() method of the JSONObject class to add elements to the array.

To create a JSON object from a string in Java, you can use the org.json library. Here's an example of how to do this:

To create a RecyclerView with multiple view types in Android, you will need to use a RecyclerView.Adapter that supports multiple view types.

Learn the two static methods of createTempFile of the File class. Use the deleteOnExit() method to ensure that the temporary created file will automatically be deleted.

"java.lang.OutOfMemoryError: Java heap space" means that the application has exhausted the maximum heap space. To fix this error, you can try the following:

To declare an ArrayList with values in Java, you can use the Arrays.asList method and pass it an array or a list of values.

To decompile a JAR file, you can use a Java decompiler such as JD-GUI.

To decompile DEX (Dalvik Executable) files into Java source code, you can use a DEX decompiler such as JD-GUI or DEX2JAR.

To deploy a WAR (Web ARchive) file in Apache Tomcat 7, you can follow these steps:

To determine the class of an object in Java, you can use the getClass() method of the Object class. The getClass() method returns a Class object that represents the object's class.

To determine the day of the week for a specific date in Java, you can use the get() method of the Calendar class.

To directly initialize a HashMap in Java, you can use the put() method to add elements to the map.

To decode a URL in Java, you can use the URLDecoder class from the java.net package.

To enter quotes in a Java string, you can use the escape character \ to indicate that the quote is part of the string, rather than the end of the string.