java basic concepts pdf

1. Holding objects The purpose of the Java Container Class library is to "save the object" and divide it into two different concepts: (1) Collection: A sequence of independent elements that obey one or more rules. The List must save the element in the order in which it was inserted, and Set cannot have duplicate elements. The queue determines the order in which objects are produced, usually

are used together. For example, to show all of the program execution process, but also to print out the relevant exceptions, it is necessary to give all the exceptions to the method call processing,For example:Class Math {public int div (int i, int j) throws Exception {System.out.println ("Start"); int temp = 0;try {temp = i/j;} CA TCH (Exception e) {//Todo:handle exceptionthrow E;} finally {System.out.println ("over");} return temp;}} public class Exceptiontest {public static void main (String

synchronized methods. The function of synchronized is to have the thread get the synchronization lock of the object.We'll analyze why Wait (), notify (), and so on are defined in the object class instead of in the thread class, when the Wait (), notify (), and other methods are described in detail later.Before we learn Java concurrency, we need to understand some basic

One.1. Download the toolkit that installs JDK,JDK as Java.2. How to configure Classpath,path.After installing the JDK, add C:\Program Files (x86) \java\jdk1.8.0_05\bin in path.Add '. ' To the Classpath3.Hello World Example.public class hello{public static void Main (String args[]) {System.out.println ("Hello world!");}}Save this file as Hello.java, noting that the naming is consistent with the class name.4.

experience and the operation, so we need multi-threading to throw the time-consuming operations into the sub-threads, so the program will continue to go on.Basic concepts and points of attention for threads1. For the operating system, the basic unit of resource allocation is the process, and the basic unit of dispatch is the thread.2. For a program, not necessar

English uppercase and lowercase letters and Arabic numerals are unsafe characters and need to be URL encoded. Here is my reference to the Tomcat source package under the Org.apache.catalina.util.URLEncoder, the String URL encoding tool class:Package Org.apache.catalina.util;import Java.io.bytearrayoutputstream;import Java.io.outputstreamwriter;import Java.util.bitset;public class urlencoder{protected static final char[] hexadecimal = {' 0 ', ' 1 ', ' 2 ', ' 3 ', ' 4 ', ' 5 ', ' 6 ', ' 7 ', '

()); System.out.println ("Balance: $" +anaccount.getbalance ()); } }Test results:Here are the account: [email protected]Account Name:zhangliAccount number:100023Balance: $100.0Declares the ToString () methodConvert the contents of an object to a stringAll classes in Java have a default ToString () method with the following method body:GetClass (). GetName () + ' @ ' + integer.tohexstring (hashcode ())The following two lines of code are equivalent:Sy

ArticleDirectory 2. Group packets 3. Protocol 4. Address 5. Domain Name System (DNS) and local configuration database 6. clients and servers 7. What is socket) ComputerProgramBeing able to communicate with the Internet makes everything possible. This is also the basis for the existence of the Internet today. So how does a program communicate with each other through the network? That's why I recorded the series of notes. The Jav