Details about HashMap and WeakHashMap that help to differentiate them are given as follows −HashMap in JavaA HashMap has key-value pairs i.e. keys that are associated with the values and the keys are in arbitrary order. A HashMap object that is specified as a key is not eligible for garbage ... Read More

A SecureRandom object can be obtained using the getInstance() method in class java.security.SecureRandom. This SecureRandom object is useful in implementing the Random Number Generator (RNG) algorithm that is specified.The getInstance() method requires a single parameter i.e. the Random Number Generator (RNG) algorithm and it returns the SecureRandom object.A program that ... Read More

The tag used as a nested action for the tag and the tag to supply a value for a value placeholder. If a null value is provided, the value is set to SQL NULL for the placeholder.AttributeThe tag has the following attributes −AttributeDescriptionRequiredDefaultValueValue of the parameter ... Read More

To update the current date and time to 5 days, you need to use the Now() + 5. That would update the entire date-time i.e. days, hour, minutes and seconds. To understand this, let us create a table. The query to create a table is as follows −mysql> create table ... Read More

A buffer can be compared with another buffer using the method compareTo() in the class java.nio.IntBuffer. This method returns a negative integer if the buffer is less than the given buffer, zero if the buffer is equal to the given buffer and a positive integer if the buffer is greater ... Read More

The errorPage attribute tells the JSP engine which page to display if there is an error while the current page runs. The value of the errorPage attribute is a relative URL.The following directive displays MyErrorPage.jsp when all uncaught exceptions are thrown −The isErrorPage attribute indicates that the current JSP can ... Read More

The tag is used to group the and tags into transactions. You can put as many and tags as statements inside the tag to create a single transaction.It ensures that the database modifications performed by the nested actions are either committed or rolled back ... Read More

To find/replace string in fields, the syntax is as follows −update yourTableName set yourColumnName =REPLACE(yourColumnName, yourOldValue, yourNewValue);To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table FindReplaceDemo    -> (    -> FileId int NOT NULL AUTO_INCREMENT PRIMARY ... Read More

The name of the algorithm for the SecureRandom object can be obtained using the method getAlgorithm() in the class java.security.SecureRandom. This method requires no parameters and it returns the name of the algorithm for the SecureRandom object.A program that demonstrates this is given as follows −Example Live Demoimport java.security.*; import java.util.*; ... Read More

Let’s say the following is our List with elements −ArrayList < String > arrList = new ArrayList < String > (); arrList.add("Jack"); arrList.add("Tom"); arrList.add("Brad"); arrList.add("Amy"); arrList.add("Ben"); arrList.add("Peter"); arrList.add("Katie"); arrList.add("Tim");Now, use the listIterator(). The next() method returns the next element in the List. Hoverer, remove an element using remove() method −ListIteratoriterator ... Read More