How-to articles, tricks, and solutions about JAVA

To convert a long value to an int value in Java, you can use the intValue method of the java.lang.Long class. This method returns the value of the specified long as an int.

In Java, an inner class is a class that is defined within another class. An inner class has access to the members (fields and methods) of the outer class, and can be used to encapsulate the implementation of a component of the outer class.

com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure is an exception that is thrown when there is a failure in the communication link between your Java program and the MySQL database. This can happen for a variety of reason

A Set is a collection of elements in which each element can only occur once. A Set does not have a specific order and does not provide a way to access its elements by their position.

To check if an array is null in Java, you can use the == operator and compare the array to null. For example:

To time the execution of a method in Java, you can use the System.nanoTime method to get the current time before and after the method is called, and then subtract the start time from the end time to get the elapsed time. Here's an example of how you can d

To convert a float to a String in Java, you can use the Float.toString method or the String.valueOf method. For example:

To capitalize the first letter of a string in Java, you can use the toUpperCase method of the java.lang.String class. Here's an example of how you can do this:

Math.random() is a method in the java.lang.Math class that returns a random double value between 0.0 (inclusive) and 1.0 (exclusive).

If you are getting the error 'Java' is not recognized as an internal or external command, it means that the Java executable is not in your system's PATH. This means that when you try to run the java command, the system does not know where to find it.

To generate a random number between two given values in Java, you can use the nextInt method of the java.util.Random class. For example:

java.lang.NumberFormatException: For input string: "N/A" occurs when you try to parse a string that cannot be converted to a number, such as the string "N/A".

java.lang.ArrayIndexOutOfBoundsException is an exception that is thrown when you try to access an element of an array with an index that is out of bounds. This can happen if you try to access an index that is either negative or greater than or equal to

In Java, you can use the length field of an array to determine the size of the array. For example, given an array arr, you can get the size of the array using arr.length.

To encode a string as Base64 in Java, you can use the java.util.Base64 class. Here's an example of how you can use the Base64 class to encode a string:

There are several ways to read and write Excel files in Java. Here are a few options:

A ClassNotFoundException occurs when the Java virtual machine (JVM) is unable to find a class that has been referenced in your code. This can happen for a number of reasons, including:

There are several tools that you can use to "decompile" Java class files and view the source code. Some popular ones include:

To get a class instance of a generic type T, you can use the new operator and specify the type argument when creating an instance of the class. Here's an example:

In Java, the == operator is used to compare the primitive values of two variables, while the equals() method is used to compare the contents of two objects.

To import a JAR file into Eclipse, follow these steps:

In Java, you can convert a double to a string using the Double.toString() method or the String.valueOf() method.

There are a few different approaches you can take to validate email addresses in Java. Here are some options:

In Java, a non-static (also known as an instance) variable or method can only be accessed from an instance of the class. A static (also known as a class) variable or method, on the other hand, can be accessed directly from the class, without the need for

In Java, it is generally recommended to use the equals() method to compare enum members, rather than the == operator.