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Thread and Java A thread is a flow of execution of a task (job) from beginning to end One of the powerful features of Java is its support for multi-threading Main Thread When you run a Java pr

Collections in Java that are called the Java Collections Framework are a set of interfaces and classes that are available for you to use in the java.util. package Java Collections Framework:

To sort an array or a collection of objects, we need to make sure that the objects are mutually comparable.  This is supported by the Comparable interface that contains only one method: compareTo(Ob

ArrayList class has many methods: add(object), add(index, object), set(index, object), get(index), remove(index), size() Initial length of new ArrayList is 10. You can also set the initial Array

Recursive programming has a method that call itself. However, we do not want to call the method itself recursively to infinity (infinite recursion). The condition that leads to a recursive method re

Arrays in Java Arrays in Java can hold primitives and references. Good for storing and accessing a sequence of data. An array in java, in terms of manipulating its data, has one method, clone(), and

Bubble sort 1. Compare two values at a time. 2. If the one on the left is bigger, swap them to BUBBLE UP the bigger value to the right. 3. Move one position to the right.

Converting words to numbers, more specifically integers. Workaround 1: Open Addressing (mainly linear probing) Step size: In linearing

The hashCode() method in Java is implemented in the Object class. Basically, the hashCode() method provides a numeric representation of an object. hashCode method in the String class uses the follow

HashTableInterface interface // HashTable interface that takes only positive integers. // No mapping, just keys public interface HashTableInterface { // Return true when the key is found. boo

Null For reference variables may not be pointing at any object - Not an object - A reserved literal value for reference type Just like "true" or "false" for boolean type - For reference types, de

When you sort an array of ints do the numbers move? Yes. When you sort an array of Objects do the Objects move? No. Why create Methods? Shorter programs - Long methods tend to have too many

Switch Statements Switch (on char, byte, short, int, String, enum) Most common mistake is leaving out the "break" statement. If you do, control continues into the next case. Default is optional.

Java Interfaces A Java Interface allows you to specify methods that must be implemented by a class - Simply speaking, it is just a list of methods, but no implementations (up to Java 7) - Several i

How do you get the time in Java? Java Time Original Unix represented time as number of seconds since 1/1/70 00:00 GMT Java represents time in milliseconds since January 1, 1970, 12:00 am GMT Java

A queue is a container of objects that are inserted and removed based on FIFO (First-in First-out) principle. In the queue, there are two major operations, enqueue and dequeue. 1. Enqueue means inse

A stack is a container of objects that are inserted and removed according to the last-in first-out (LIFO) principle. Simply speaking, there are two major operations. 1. Push: push an item onto the t

LinkedList is one of the two general-purpose List implementations. In addition to some general and common methods, LinkedList in Java also offers a few methods that work with the elements at the begin

Why use Java？ - Programming Language with the "Right stuff" - Runs "everywhere" Right stuff: - Objected-oriented - Network-oriented - Large Class Libraries - Multithreaded - High-performan

JAPL: Just Another Programming Language - Data Types, Literals, Variables, Expressions, Statements, Methods, Arrays, Comments. Primitive Data Types - Written in lower case letters - Declares s

What is a Class? A class is a templete definition (blueprint) It defines the data contained in objects that are members of a class It defines the methods (operations) that can be performed on those

N-JAPL: Not Just Another Programming Language - Objects - Portable (Write once, Run anywhere) Create a object in Java: 1. Create a class to define a new type public class Rectangle { int

Given two non-negative numbers num1 and num2 represented as string, return the sum of num1 and num2. Note: The length of both num1 and num2 is Both num1 and num2 contains only digits 0-9.B