notes on core java in java

Public – main method is called by JVM to run the method which is outside the scope of project therefore the access specifier has to be public to permit call from anywhere outside the application static – When the JVM makes are call to the main method there is not object existing for the class … Read more

A thin wrapper around a millisecond value that allows JDBC to identify this as an SQL DATE value. A milliseconds value represents the number of milliseconds that have passed since January 1, 1970 00:00:00.000 GMT. To conform with the definition of SQL DATE, the millisecond values wrapped inside a java.sql.Date instance must be ‘normalized’ by … Read more

Finally is the block of code that executes always. The code in finally block will execute even if an exception is occurred. Finally block is NOT called in following conditions If the JVM exits while the try or catch code is being executed, then the finally block may not execute. This may happen due to … Read more

This Error is thrown when the Java Virtual Machine cannot allocate an object because it is out of memory, and no more memory could be made available by the garbage collector. Note: Its an Error (extends java.lang.Error) not Exception. Two important types of OutOfMemoryError are often encountered lang.OutOfMemoryError: Java heap space The quick solution is to add … Read more

The Java Spec says that everything in Java is pass-by-value. There is no such thing as “pass-by-reference” in Java. The difficult thing can be to understand that Java passes “objects as references” passed by value. In Java, the argument passing mechanism is often a source of confusion. Java is always “pass-by-value,” but it’s essential to … Read more