Java Core Classes and Threads

If we want to convert all the characters in a string object into a character array, we use the method toCharArray().

getItemSelectable() method can be used to obtain a reference to the Item Selectable object that generate an event.

NullPointer exception is thrown when an application attempts to use null where an object is required.

ArrayIndexOutOfBounds exception is thrown when an attempt is made to access element beyond the index of the array.

Event source is an object that generates an event.

Object of the Scanner class are useful in breaking down the inputs from the user into tokens, and these tokens can be converted into individual basic data types.

The nextToken() is the method of a StringTokenizer() class, and ttype is the filed name.

The PushBackReader class is not directly derived from the Reader class.

The LineNumberInputStream, DataInputStream, BufferedInputStream, and PushBackInputStream classes are derived from FilterInputStream class.

The countTokens() method is used to calculate the number of times the tokenizer's nextToken method can be called before it generates an exception

We can create a new thread using two ways:

1. Declare a class to be a subclass of Thread class.
2. Declare a class that implements the Runnable interface.

The code we want to execute has to be place in a method run() of the class which extends class Thread. This function will automatically call by using start().

The correct structure is: class MyClass extends Thread {       public void run()       {       } }

The join() method of thread class makes the current thread to wait until other specified thread terminates.

All these methods must be called only when they own the monitor of that object, otherwise they throw IllegalMonitorStateException exception. These methods are used for proper coordination among the threads.