top 100 java programs pdf

The biggest advantage of writing applications in the Java language is "compile once, run everywhere", but this is not to say that all Java programs have cross-platform features, and in fact, quite a few Java programs do not operate correctly on other operating systems. So ho

The biggest advantage of writing applications in the Java language is "compile once, run everywhere", but this is not to say that all Java programs have cross-platform features, and in fact, quite a few Java programs do not operate correctly on other operating systems. So ho

The biggest advantage of writing applications in the Java language is "compile once, run everywhere", but this is not to say that all Java programs have cross-platform features, and in fact, quite a few Java programs do not operate correctly on other operating systems. So ho

.Debugging a large number of threadsSometimes a program is very difficult to debug because it has a large number of threads running. In this case, the following class might come in handy:public class Probe extends Thread {public Probe () {} public void Run () {while (true) { thread[] x = new T HREAD[100]; Thread.enumerate (x); for (int i=0; iRestricting thread priority and schedulingThe

static void Main (string[] ArGS) {oraclejdbctest test = new Oraclejdbctest (); Test.init (); Test.fetch (); }4. Util Java. Date turns into SQL. DateJava.util.Date utildate = new Java.util.Date (); 5. Create a thumbnail image of a pictureprivate void Createthumbnail (string filename, int thumbwidth, int thumbheight, int quality, string outfilename) Throws Interruptedexception, FileNotFoundException, IOException {//load image from

encapsulated in the request object. 2) After processing the request, the response object will get java. io. printWriter outputs the stream object out through out. println (); the data is in the specified format, for example, according to response. setcontentType ("text/html; charset = gb2312"); format output to the output stream. The response message is very similar to the request message. The difference is that the request line in the request stage

algorithm for the signature. Common algorithms are specified in Java reference. Use the Signatur instance to initSign(PriKey) initialize the signature or initVerify(pubkey) to initialize the authentication. The input that uses the Signatur instance update(bytes) requires the data to be signed. Use the Signatur instance sign() or verify() implement the signature or authentication. Note that the former returns byte[] and the latter returns

Writing high-quality code: 151 suggestions for improving Java programs (Chapter 1: classes, objects, and Methods ___ 31 ~ 35), java151 If you read many books without thinking about them, you will feel that you know a lot. When you read a lot of books and think about it, you will feel that you do not understand more and more. --- Voltaire In the Object-Oriented Programming (OOP) World, classes and objects ar

discarded, changed, and reconstructed at any time. Therefore, although the interface can be implemented, but should avoid the use.Note: The implementation code cannot appear in the interface.Back to top recommendation 32: Static variables must first be declared after assignmentis the title as depressing as the last suggested title? What is called a variable must first be declared after the assignment? are variables in Java not all declared and used b

objects.2. Preparation knowledgeBefore analyzing this example, let's take a look at several concepts about threads, locks, semaphores, and Java APIs.LockFor most programs, they need to communicate with each other to complete the life cycle of the entire thread. The simplest way to achieve synchronization between threads is locking. To prevent the two associated threads from mistakenly accessing shared reso

2nd java sample programs-general Linux technology-Linux programming and kernel information. The following is a detailed description. For programming languages, variables are the most basic concept. You may know that a variable is a memory location with a name and can be assigned a value. In addition, the variable value can be changed during the running of the program. The next program will introduce how to

packageHashcodebuilderBuild49, recommended to overwrite the ToString method:java provides the default ToString method is not friendly, print out only the machine can read, its format is the class name +@+hashcode, so it is recommended to overwrite the toString method so that we could debug50, use the package-info class for the package service: in the need to use the package, you can consider this special class51, do not actively garbage collection: in the application do not directly use System

Testreportgenerator {/** * @param args */public static void main (string[] args) {L ist3. Parameters associated data source via ireportCan see. Resultslist is the Jrbeancollectiondatasource type, in which the program passes through Parameters.put ("Resultslist", Resultslist), The Testbean data collection to be used by the Linechart is passed, and the data set is obtained by $p{report_parameters_map}.get ("Resultslist") in the ireport configuration.Finally run the test program, can be iss

Writing high-quality code: 151 suggestions for improving Java programs (Chapter 1: Basic Types ___ suggestions 26 ~ 30), java151Recommendation 26: Beware of null values of the packaging type We know that Wrapper Types is introduced to Java to solve the instantiation problem of basic Types, so that a basic type can also be involved in the object-oriented programmi

151 suggestions for improving java programs-Note 1, java151-Note I. common methods and guidelines for Java Development 1. do not contain confusing letters in constants and variables. Eg: long I = 1l. Is this 11 or lL? We recommend that you use uppercase letters; 2. Do not change constants into variables. Eg: public static final int RAND_CONST = new Random (). nex

This article collects some tips on how to reduce the footprint of Java programs online.(1) Do not use the new Boolean ().In many scenarios, a Boolean type is required, such as the Boolean type set and get in JDBC are passed through a Boolean wrapper, and most ORM uses a Boolean to encapsulate the Boolean type, for example:Ps.setboolean ("isClosed", New Boolean (true));Ps.setboolean ("isClosed", New Boolean

result will be the inaccurate problem of floating-point arithmetic. Six, (1) What is the output of the following code? int x=100;int y=200;System.out.println ("x+y=" +x+y);System.out.println (x+y+ "=x+y");The result: x+y=100200 300=x+y(2) Why are there such output results?A: Because a variable of type string plus any other basic type of variable will be treated as a string. And the output of the first statement inside x+y is not enclosed in parenthe

key to this step is to configure the blue number number in order: $P {report_parameters_map}.get ("resultslist"), where the key value of the data source is passed in a later program "Resultslist", Be consistent with the key value here, otherwise you will not get the data passed.After the configuration is complete, click "Compilereport" to regenerate the. jasper file.2. Call Jasperrunmanager Several static methods, such as runreporttopdf,runreporttohtmlfile, etc.;The sample program is as follows

0:iload_0 1:iload_1 2:iadd 3:ireturn linenumbertable: Line 18:0 public static int MethodB (int, int); Signature: (II) I flags:acc_public, Acc_static code:stack=2, locals=2, args_size=2 0:iload_0 1:iload_1 2:isub 3:ireturn linenumbertable: Line 22:0 public static int methodc (int, int); Signature: (II) I flags:acc_public, Acc_static code:stack=2, locals=2, args_size=2 0:iload_0 1:iload_1 2:imul 3:ireturn l

Tomcat + java web programs continue to occupy cpu issues for debugging Symptom: Deploy Java web applications in tomcat. After a while, the java Process of tomcat continues to occupy up to 100% of the cpu, leading to blocked web application access. Possible Cause Analysis: T