How-to articles, tricks, and solutions about JAVA

To generate a random alpha-numeric string in Java, you can use the Random class and the nextInt and nextBoolean methods to generate random characters and append them to a StringBuilder. Here's an example of how you might do this:

To create a Java string from the contents of a file, you can use the following code:

To convert an ArrayList<String> to a String[] array in Java, you can use the toArray method of the ArrayList class and pass it an empty array of the appropriate type:

This error can occur when you are trying to run a Java program and the Java Virtual Machine (JVM) cannot find the required shared libraries. There are a few different causes of this error and a few different things you can try to fix it:

There are a few different ways you can remove whitespace from strings in Java. Here are a few options: Using the replaceAll method:

To convert an array to a list in Java, you can use the Arrays.asList() method. This method returns a fixed-size list backed by the specified array. Here's an example:

To check if a String is numeric in Java, you can use the isNumeric method of the StringUtils class from the org.apache.commons.lang3 library.

To initialize a List<String> object in Java, you can use one of the following approaches: Using the new keyword:

To get user input in Java, you can use the Scanner class. Here's an example of how to get a string input from the user:

To make a delay in Java, you can use the Thread.sleep method which will pause the current thread for a specified number of milliseconds. Here's an example:

To convert a JSON string to a JSONObject in Java, you can use the JSONObject constructor that takes a String as an argument, like this:

There are several ways to round a number to n decimal places in Java:Using DecimalFormat

"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 get the current date and time in Java, you can use the <code>java.time</code> package introduced in Java 8.

To parse a JSON string in Java, you can use the org.json library. This library provides a simple and easy-to-use interface for parsing and manipulating JSON data in Java.

To convert a string to a date in Java, you can use the parse method of the SimpleDateFormat class.

To convert an int to a String in Java, you can use the Integer.toString() method. For example

In Java, arguments are passed to methods by value. This means that when you pass an argument to a method, the method receives a copy of the argument rather than a reference to the original object.

There are several ways to read an InputStream and convert it to a String in Java. One way is to use the BufferedReader and InputStreamReader classes to read the InputStream line by line, and use a StringBuilder to construct the final String:

In the Java programming language, the accessibility of a class, method, or field can be controlled using access modifiers. There are four access modifiers in Java:

To check if an array contains a particular value in Java, you can use the contains() method of the List interface, which is implemented by the ArrayList class.

The -Xms and -Xmx options are used to set the initial and maximum heap sizes, respectively, for the Java Virtual Machine (JVM).

In Java, you can create a new list using the java.util.ArrayList class or the java.util.LinkedList class.

This code opens the file "filename.txt" and reads it line by line. Each line is printed to the console until the end of the file is reached.

There are several ways to print an array in Java. Here are a few options: Using a loop