Free Java Advanced Theory Notes For Beginners1

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AWT control fundamentals in java-part 3

AWT components in java Choice control The choice control contains a list of choices from which one can be selected. When it is inactive it takes the same Space as that of a single choice. Choice has only one default constructor, namely: Choice choice1 = new Choice(); Here choice1 is the object name, the programmer can give the desired name as the object name. To add items to the choice created in the above statement, The following method can be used. choice1.addltem(String); choice1.add(String); To get the selected item, the method getSelected Item() is used and the index of the Selected item can be obtained using the method get selectedindex(). Items can also be selected using Select( int index) and Select (String name) when either the index or the name of the item is Known. List control. The list control is similar to the choice control, but multiple items can be selected using the list control.Here the number rows to be visible in the list can be specified, Whereas in the choic...

AWT controls in Java-part 2

Java simple theory notes for AWT controls part2 java AWT CheckBox A check box is a graphical component that can be in either an "on" (true) or "off" (false) state. Clicking on a check box changes its state from "on" to "off," or from "off" to "on." In other words, the checkbox control is used to select or deselect different options.These control also have a label associated with them which describe the option of the checkbox. How to create a label? syntax for creating labels: Checkbox cbox1=new Checkbox(); Checkbox cbox2=new Checkbox(String); Checkbox cbox3=new Checkbox(String,boolean); Here cbox1,cbox2,cbox3 are the object name, the programmer can give the desired name as the object name. Given above are three types of constructor for the checkbox The first one creates a blank default checkbox.The label for checkbox can be set using the setLabel() method The second constructor creates a checkbox with the specified labe...

AWT controls in Java-Beginners note-part 1

Java simple theory notes for AWT controls part1 AWT controls ( java AWT ) Controls are components that allow the user to interact with an application. `A component is a visual object containing text or graphics.It can respond to keyboard or mouse input.The java AWT supports several types of control.These are listed below: Labels Buttons Lists Radio Buttons Scroll Bars Text Field Choice Lists Text Area Check Boxes Labels Labels are used to present some type of interactive information on a container.These will not interact with the user and do not fire any event.so, there is no Listener class for the labels.Labels are used for display purpose only.A Container is a graphical object that contains component or container. How to create a label? syntax for creating labels: Label label1=new Label(); Label label2=new Label(String); Label label3=new Label(String,int); Here label1,label2,label3 is the object name, the programmer can give the desired name as the object name. Given abov...

Java coding questions and answers

Advanced java coding questions and answers for practice 1. What is the purpose of the java.util.stream package in Java, and how does it support functional-style operations on collections? Answer: The java.util.stream package provides a powerful API for functional-style operations on collections, including filtering, mapping, and reducing, making it easier to work with data in a declarative manner. 2. Explain the concept of serialization and deserialization in Java, and discuss the role of the Serializable interface? Answer: Serialization is the process of converting an object into a byte stream for storage or transmission, while deserialization is the reverse process. The Serializable interface is used to mark classes as serializable, allowing their objects to be serialized. 3. What is the java.util.function package in Java, and how does it provide functional interfaces for use with lambda expressions and method references? Answer: The java.util.function package defines functi...

Advanced java interview-Q and A

Core java basic interview questions and answers 1 . What is the purpose of the ThreadLocal class in Java, and how is it used for managing thread-local variables? Answer: ThreadLocal allows you to create variables that are local to each thread, ensuring thread safety without synchronization. Each thread accesses its own copy of the variable. 2 . Describe the Java 8 features related to functional programming, including lambdas and the Stream API? Answer: Java 8 introduced lambdas for defining functions, and the Stream API for working with collections in a functional style, enabling concise and expressive code. 3. What is a Java annotation processor, and how can it be used for code generation or validation? Answer: An annotation processor processes annotations at compile-time, allowing you to generate code, perform validations, or automate tasks based on annotations in your code. 4. Explain the principles of method chaining and builder design pattern in Java, and their benefits? A...

Advanced java for beginners-Q and A

Java coding interview questions and answers for Freshers 1. Explain the super keyword in Java and its use in constructor chaining? Answer: super is used to call a superclass's constructor or access superclass members. It's commonly used in constructor chaining to call the superclass constructor from a subclass constructor. 2. What is the purpose of the synchronized keyword in Java, and how does it work? Answer: synchronized is used to create synchronized blocks or methods to provide thread-safety by allowing only one thread to access a synchronized block at a time. 3. What is the purpose of ‘this’ keyword in Java, and how is it used? Answer: The ‘this’ keyword refers to the current instance of a class and is often used to distinguish between instance variables and method parameters with the same name. 4. What are inner classes in Java , and why are they used? Answer: Inner classes are classes defined within another class. They are used for encapsulation, organization, a...