How-to articles, tricks, and solutions about JAVA

In Java, you can cast a double value to an int using the (int) operator. This will truncate the decimal part of the double and return the integer value.

To check if a string contains a number and extract the number from the string in Java, you can use a combination of the matches method of the String class and the find method of the Matcher class.

To check if a String contains a special character in Java, you can use a regular expression to match any character that is not a letter or a digit.

To check if a string is not null and not empty in Java, you can use the length() method of the java.lang.String class to check if the string is empty, and the != operator to check if the string is not null. Here is an example of how you can do this:

To check whether a number is even or odd in Java, you can use the modulus operator (%) to determine the remainder of the number when it is divided by 2.

To check if a string is empty or null in Java, you can use the isEmpty() method of the java.lang.String class, which returns true if the string is empty, and false if it is not. Here is an example of how you can use isEmpty() to check if a string is empty

If you get the error "class has been compiled by a more recent version of the Java Environment", it means that you are trying to run a class file that was compiled with a newer version of Java than the one you have installed.

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

To compare two char values in Java, you can use the == operator, just like you would with any other primitive type. For example:

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

To compare strings by their alphabetical order in Java, you can use the compareTo() method of the String class.

To connect a Java application to a MySQL database, you need to use the JDBC (Java Database Connectivity) API.

console.writeline is not a valid method in Java.

Here is an example of how you can convert a JSON string to a HashMap in Java:

To convert a string representation of a hex dump to a byte array in Java, you can use the DatatypeConverter class's parseHexBinary method.

To convert an integer to an array of digits in Java, you can use the toCharArray() method of the String class to convert the integer to a string, and then use the toCharArray() method to convert the string to an array of characters.

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:

To convert a boolean value to an integer in Java, you can use the intValue() method of the java.lang.Boolean class, or you can use a conditional operator.

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.

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

To convert an InputStream to a byte array in Java, you can use the readAllBytes() method of the java.nio.file.Files class from the java.nio.file package.

To convert an int value to a char value in Java, you can use the char type's conversion method, (char).

To convert a java.time.LocalDate into a java.util.Date type in Java, you can use the atStartOfDay() method of the LocalDate class to get a LocalDateTime object and then use the toInstant() method to convert it to an Instant object.

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 convert a java.util.Date object to a String, you can use the format method of the SimpleDateFormat class from the java.text package. The SimpleDateFormat class provides a convenient way to convert a Date object to a String based on a specified format.