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Articles by raja
Page 2 of 38
Can we write any statements between try, catch and finally blocks in Java?
No, we cannot write any statements in between try, catch and finally blocks and these blocks form one unit. The functionality of try keyword is to identify an exception object and catch that exception object and transfer the control along with the identified exception object to the catch block by suspending the execution of the try block. The functionality of the catch block is to receive the exception class object that has been sent by the try and catch that exception class object and assigns that exception class object to the reference of the corresponding exception class defined in the catch block. The finally blocks are ...
Read MoreCan a constructor throw an exception in Java?
Yes, constructors are allowed to throw an exception in Java.A Constructor is a special type of a method that is used to initialize the object and it is used to create an object of a class using the new keyword, where an object is also known as an Instance of a class. Each object of a class will have its own state (Instance variables) and access to methods of its class.Throw an Exception from a ConstructorA checked exception can be used to indicate a legitimate problem when trying to create an instance, while an unchecked exception typically indicates a bug either in the ...
Read MoreHow many types of anonymous inner classes are defined in Java?
An anonymous inner class is an inner class which is declared without any class name at all. In other words, a nameless inner class is called an anonymous inner class. Since it does not have a name, it cannot have a constructor because we know that a constructor name is the same as the class name.We can define an anonymous inner class and create its object using the new operator at the same time in one step.Syntaxnew(argument-list){ // Anonymous class body }Types of Anonymous Inner Class in JavaAnonymous inner class that extends a classAnonymous inner class that implements an interfaceAnonymous inner ...
Read MoreWhat is an OutOfMemoryError and steps to find the root cause of OOM in Java?
The OutOfMemoryError is thrown by JVM, when JVM does not have enough available memory, to allocate. OutOfMemoryError falls into the Error category in Exception class hierarchy.To generate OutOfMemoryErrorWe will allocate a large chunk of memory, which will exhaust heap memory storage.We will keep on allocating the memory and point will reach, when JVM will not have enough memory to allocate, then OutOfMemoryError will be thrown.Once we will catch the OutOfMemory error, we can log the error.Examplepublic class OutOfMemoryErrorDemo { public static void main(String[] args) throws Exception { int dummyArraySize = 15; System.out.println("Max JVM memory: " + Runtime.getRuntime().maxMemory()); ...
Read MoreWhat is a Type-safe Enum in Java?
In Java, an enum is a special class that represents a "group of constants" that cannot be changed, just like a "final variables". Java provides an enum keyword to create an enum, and inside the class, the constants are written in uppercase letters and separated by commas (, ). Syntax to create an enum in Java: enum EnumName { CONST1, CONST2, CONST3 // ... } Here, enum: A predefined keyword used to define an enum. EnumName: The name ...
Read MoreWhat are the differences between GridLayout and GridBagLayout in Java?
In Java, a GridLayout puts all the components in a rectangular grid and is divided into equal-sized rectangles, and each component is placed inside a rectangle whereas GridBagLayout is a flexible layout manager that aligns the components vertically and horizontally without requiring that the components be of the same size. Java GridLayout A GridLayout arranges the components in a rectangular grid. It arranges components in the cells, and each cell has the same size. Components are placed in columns and rows. GridLayout(int rows, int columns) takes two parameters that are a column and a row. Syntax The following is the ...
Read MoreHow to create a custom unchecked exception in Java?
In Java, the exceptions are of two types: checked and unchecked exceptions. A checked exception is an exception that occurs at compile time; these are also called compile-time exceptions. An unchecked exception occurs at the time of execution. These are also called Runtime Exceptions. In this article, we will learn to create a custom unchecked exception in Java. We can create a custom unchecked exception by extending the RuntimeException class in Java. What are unchecked exceptions? The unchecked exceptions inherit from the Error class or the RuntimeException class. Many programmers feel that we cannot handle these exceptions in our programs because they represent the type of errors ...
Read MoreHow can we implement a JLabel text with different color and font in Java?
In this article, we will learn to implement a JLabel text with different colors and fonts in Java. JLabel is commonly used for simple text display, it can be enhanced to show text with multiple colors and fonts. JLabel A JLabel class can extend the JComponent class, and an object of JLabel provides text instructions or information on a GUI. A JLabel can display a single line of read-only text, an image, or both text and an image. A JLabel can explicitly generate a PropertyChangeListener interface. Different Approaches The following are the two different approaches to implementing a JLabel text ...
Read MoreHow to change each column width of a JTable in Java?
In this article, we will learn to change each column width of a JTable in Java. JTable is Swing's strongest component for displaying and editing tabular information. Adjusting column widths appropriately to display content is among the most prevalent needs for customization. JTable A JTable is a subclass of JComponent for displaying complex data structures. A JTable can follow the Model View Controller (MVC) design pattern for displaying the data in rows and columns. The DefaultTableModel class can extend AbstractTableModel and it can be used to add the rows and columns to a JTable dynamically. Syntax The following is ...
Read MoreWhat are the differences between a Font and a FontMetrics in Java?
The Font class in Java is responsible for setting screen fonts, which are mapped to characters of the language in specific regions. But a FontMetrics class is said to be a font metrics object that encapsulates the data about the rendering of a specific font on a particular screen. Font A Font class can be used to create an instance of a Font object to set the font for drawing text, labels, text fields, buttons, etc, and it can be specified by its name, style, and size. Syntax The following is the syntax for Font initialization: Font font = new ...
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