A final class can’t be extended i.e. A final class can not be subclassed. A final method can’t be overridden when its class is inherited. You can’t change value of a final variable (i.e. it is a constant). Modifier Class Method Variable static A static inner class is just an… Continue reading
Static variables Instance variables Class variables are called static variables. There is only one occurrence of a class variable per JVM per class loader. When a class is loaded the class variables (aka static variables) are initialized. Instance variables are non-static and there is one occurrence of an instance variable… Continue reading
The default behavior of an object’s clone() method automatically yields a shallow copy. So to achieve a deep copy the classes must be edited or adjusted. Shallow copy: If a shallow copy is performed on obj-1 as shown in fig-2 then it is copied but its contained objects are not…. Continue reading
Java applications that utilize Input/Output are excellent candidates for performance tuning. Profiling of Java applications that handle significant volumes of data will show significant time spent in I/O operations. This means substantial gains can be had from I/O performance tuning. Therefore, I/O efficiency should be a high priority for developers… Continue reading
Java has long been not suited for developing programs that perform a lot of I/O operations. Furthermore, commonly needed tasks such as file locking, non-blocking and asynchronous I/O operations and ability to map file to memory were not available. Non-blocking I/O operations were achieved through work around such as multithreading… Continue reading
Java input and output is defined in terms of an abstract concept called a “stream”, which is a sequence of data. There are 2 kinds of streams. Byte streams (8 bit bytes) -> Abstract classes are: InputStream and OutputStream Character streams (16 bit UNICODE) -> Abstract classes are: Reader and… Continue reading
Say you create a “Car” class, instantiate it, and write it out to an object stream. The flattened car object sits in the file system for some time. Meanwhile, if the “Car” class is modified by adding a new field. Later on, when you try to read (i.e. deserialize) the… Continue reading
Do not use serialization if you do not have to. A common use of serialization is to use it to send an object over the network or if the state of an object needs to be persisted to a flat file or a database. Deep cloning or copy can be… Continue reading
Transient variables cannot be serialized. The fields marked transient in a serializable object will not be transmitted in the byte stream. An example would be a file handle, a database connection, a system thread etc. Such objects are only meaningful locally. So they should be marked as transient in a… Continue reading
Serialization is a process of reading or writing an object. It is a process of saving an object’s state to a sequence of bytes, as well as a process of rebuilding those bytes back into a live object at some future time. An object is marked serializable by implementing the… Continue reading