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H Java примеры из книг и документации в черновиках Recovery Mode Tutorial

Java

  1. Basics
  2. IO
  3. System
  4. Threads
  5. Net
Набор примеров составленных из книг и документации. PDF + Исходники
Java books and internet samples by padaboo I.B Aleksandrov



Basics


Data types.
package basics;
/**
*
* @author Padaboo I.B Aleksandrov
*/
public class DataTypes {

public static void main(String[] args) {
DataTypes app = new DataTypes();

//int 4byte -2147483648 2147483648
int i = 1;
//short 2byte -32768 32767
short s = 1;
//long 8byte -9223372036854775808 -9223372036854775807
long l = 1;
//byte 1byte -128 до 127
byte b = 1;
//float 4byte +-3,40282347E+38F
float f = 0.1f;
//double 8byte +-1,7976931348623157E+308F
double d = 0.2f;
//char
char c = 'd';
//boolean true false logical 1/0
boolean bool = true;
}
//public static constatn available in any method in other classes
//a constant can not be changed
public static final double con = 0.3f;
}

Math
package basics;
/**
* https://docs.oracle.com/javase/tutorial/java/data/beyondmath.html
* @author padaboo I.B Aleksandrov
*/
public class JavaMath {
public static void main(String[] args) {
/**
Math.abs (n) - returns the unit number n.
Math.round (n) - returns an integer closest to a real number n (rounds n).
Math.ceil (n) - returns the closest number to the number n to the right of zero fractional part
(e.g., Math.ceil (3.4) returns a result of 4.0).
Math.cos (n), Math.sin (n), Math.tan (n) - trigonometric function sin, cos tg and the argument n,
indicated in radians.
Math.acos (n), Math.asin (n), Math.atan (n) - inverse trigonometric functions return the angle in
radians.
Math.toDegrees (n) - a measure of returns-degree angle in radians n.
Math.toRadians (n) - returns radian measure of an angle in degrees n.
Math.sqrt (n) - returns the square root of n.
Math.pow (n, b) - returns the value of the power function of degree n b, the base and the
exponent may be real.
Math.log (n) - returns the natural logarithm of n.
Math.log10 (n) - returns the logarithm of n.
*/
System.out.println(Math.abs(-2.33));
System.out.println(Math.round(Math.PI));
System.out.println(Math.round(9.5));
System.out.println(Math.round(9.5-0.001));
System.out.println(Math.ceil(9.4));
double c = Math.sqrt(3*3 + 4*4);
System.out.println(c);
double s1 = Math.cos(Math.toRadians(60));
System.out.println(s1);
}
}

Operations
package basics;
/**
*
* @author Padaboo I.B Aleksandrov
*/
public class Operations {

public static void main(String[] args) {
Operations app = new Operations();
/**
* + sum
* - subtraction
* / division
* * multiplication
* % remainder of the division
*/
int x = 1;

x = x + x;

System.out.println(x);
//2

//x+1
++x;
System.out.println(x);
//3

x += 2;
System.out.println(x);
//5

/**
* Logical operations
* == equally
* != not equally
* <= less or equal
* => more or equal
* < less
* > more
* && and
* || or
*/

boolean result = (x != 1);

System.out.println(result);
//true

result = ((x != 1) && (x == 2));

System.out.println(result);
//false

//ternar (condition) ? expression_1 : expression_2
//if the expression is true if the first part is done there is no second

result = x>3 ? true : false;

System.out.println(result);

/**
* byte operations
* & byte and
* | byte or
* ^ excluding or
* ~ not
* >> bit shift to the right
* << bit shift to the left
*/

/**
* Priority
* [] () from right to left
* !~++--+()new from right to left
* * / % from left to right
* + - from left to right
* << >> >>> from left to right
* < <= > >= instanceof from left to right
* == != from left to right
* & from left to right
* ^ from left to right
* | from left to right
* && from left to right
* || from left to right
* ?: from right to left
* = += -= *= /= %= |= ^= <<= >>= >>>= from right to left
*/

// null - empty field
// nan - not a number

}
}

Constructions

package basics;
/**
*
* @author Padaboo I.B. Aleksandrov
*/
public class Constructions {
//public, visible inside and outside
public int pub = 1;
//private, visible inside
private int pri = 2;
//protected, visible inside and in child class
protected int pro = 3;

//public static varible
public static int staticVar = 4;
//constant
public final static int finalVar = 4;
//enum is used as a constant
enum Modifier {
PUBLIC,
PROTECTED,
PRIVATE,
ABSTRACT,
STATIC,
FINAL,
TRANSIENT,
VOLATILE,
SYNCHRONIZED,
NATIVE,
STRICTFP;
}

public static void main(String[] args) {
//local varible of method (funttion)
int localVarible = 0;

//create exemplar of class (object) constructions
Constructions constructions = new Constructions();
//if condition
if(1 == 1){
//true
} else {
//false
}

//else if
if (false){
}else if (false){

}else {
//do
}

//for: repeating cycle with the condition 1
for(int i=1; i<5; i++){
System.out.println("i is: " + i);
}

//for: repeating cycle with the condition 2
int[] numbers = {1,2,3,4,5,6,7,8,9,10};
for (int item : numbers) {
System.out.println("i is: " + item);
}

//while true
int n = 5;
while (n > 0) {
System.out.println("while " + n);
n--;
}
//do while true
int i = 0;
do{
System.out.print ("while " + ++i);
} while (i < 10);

//continue skip iteration/next

//new create a new object
String s = new String();

//selection operator
int month = 3;
switch (month) {
case 1: s = "1";
break;
case 2: s = "2";
break;
case 3: s = "3";
break;
case 4: s = "4";
default: break;
}
//print case result
System.out.println(s);
//private varible
System.out.println(constructions.pri);
//public varible
System.out.println(constructions.pub);
//protected varible
System.out.println(constructions.pro);
System.out.println(staticVar*2);

//call function from object
System.out.println(constructions.func());
//call overload function func with 2 arguments
System.out.println(constructions.func(2,2));

//call enum Modifier
Modifier variableModifier = Modifier.PUBLIC;
System.out.println(variableModifier);

}

/**
* private function return type int, no arguments
*/
private int func(){
//do
return 128;
}

/**
* function overloading with 2 arguments
* @param a
* @param b
* @return int
*/
private int func(int a,int b){
return a*b;
}
}

Strings
package basics;
/**
*
* @author Padaboo I.B. Aleksandrov
*/
public class Strings {
public static void main(String[] args) {
String j = "jmonkey";
String e = "engine";

//concatenation

System.out.println(j+3);
//jmonkey3

System.out.println(j + " " + e);

//equals ==

System.out.println(j.equals("jmonkey"));

//length
System.out.println(j.length());

//substring start end
System.out.println(j.substring(0,3));
//jmo

//first symbol
char first = j.charAt(0);
//j
System.out.println(first);
char arr[] = {'j','m','3'};

String fromchar = new String(arr);

System.out.println(fromchar);

//JDK API String https://docs.oracle.com/javase/7/docs/api/java/lang/String.html

}
}

Arrays
package basics;
import java.util.ArrayList;
/**
* Java arrays
* @author Padaboo I.B Aleksandrov
*/
public class Arrays {
public static void main(String[] args) {
//create array of integer size 3
int[] a = new int[3];

a[0] = 1;
a[1] = 2;
a[2] = 3;

int[] b = {1,2,3};

for(int j = 0; j <= b.length - 1; j++) {
System.out.println(b[j]);
}

//multidimensional array
int[][] ab = new int[6][4];
//int[][] ab = {{2,3},{2,2}};

for(int i=0; i<ab.length; i++) {
for(int j=0; j<ab[i].length; j++) {
ab[i][j] = (int)(Math.random()*10);
}
}

//array of objects
Car[] cars = new Car[10];

//array list
ArrayList carList = new ArrayList();

int i = 0;
//add objects to array list
while(i< 3){
carList.add(new SportCar());
}

Car[] carsArray = new Car[carList.size()];

carList.toArray(carsArray);
//add(n,e);
//remove(n);

//https://docs.oracle.com/javase/7/docs/api/java/util/ArrayList.html
}
}

Collections
package basics;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Queue;
import java.util.Set;
import java.util.TreeMap;
/**
* LinkedList HashMap LinkedHashMap TreeMap
* https://docs.oracle.com/javase/7/docs/api/java/util/Collections.html
* @author Padaboo I.B. Aleksandrov
*/
public class Collections {
public static void main(String[] args) {
Collections app = new Collections();

//app.LinkedListExample();
//app.HashMapExample();
//app.LinkedHashMap();
//app.TreeMapExample();
app.QueueExample();
}

private void LinkedListExample(){
//Java LinkedList
List list = new LinkedList();
list.add("player 1");
list.add("player 2");
list.add("player 3");
Iterator iter = list.iterator();

while(iter.hasNext()){
System.out.println(iter.next());
}

for(int num=0; num<list.size(); num++){
System.out.println(list.get(num));
}

for (Iterator it = list.iterator(); it.hasNext();) {
String str = it.next();
System.out.println(str);
}

list.get(0);

list.set(1,"Monster");

list.remove(0);

list.size();
//https://docs.oracle.com/javase/7/docs/api/java/util/LinkedList.html
}

private void HashMapExample(){
//java HashMap Example
Map<String, Car> hashmap = new HashMap<String, Car>();

hashmap.put("id1", new SportCar());
hashmap.put("id2", new SportCar());
hashmap.put("id3", new SportCar());

SportCar iterCar;

for (Map.Entry entry : hashmap.entrySet()) {
iterCar = (SportCar)entry.getValue();
System.out.println("key: " + entry.getKey() + " val: "+ iterCar.getSpeed());
}
}

private void LinkedHashMap(){
//Java LinkedHashMap Example
LinkedHashMap<Integer, String> map =
new LinkedHashMap<Integer, String>();
map.put(1, "Java");
map.put(2, "Jmonkey");
map.put(3, "3d");
map.put(4, "Convas");
map.put(5, "ClientServer");
//map.get(4);

Set set = map.entrySet();

Iterator iterator = set.iterator();
Map.Entry me;
while(iterator.hasNext()) {
me = (Map.Entry)iterator.next();
System.out.println("key: "+ me.getKey() + " val: "+me.getValue()+"\n");
}
}

private void TreeMapExample(){
TreeMap<Integer, String> tmap =
new TreeMap<Integer, String>();
tmap.put(1, "Blender");
tmap.put(3, "Ogre3D");
tmap.put(70,"Animation");
tmap.put(4, "Shaders");
for (Entry<Integer, String> entry : tmap.entrySet()) {
System.out.println(entry.getKey() + " - " + entry.getValue());
}
}

private void QueueExample(){
Queue qe=new LinkedList();
qe.add("Java Oracle");
qe.add("Ubuntu Linux");
qe.add("Convas 3d");
for (String iteratorValue : qe) {
System.out.println("Queue Next Value :"+iteratorValue);
}
}
}

Try cahtch


package basics;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* https://docs.oracle.com/javase/tutorial/essential/exceptions/
* @author padabo I.B Aleksandrov
*/
public class ExceptionTryCatchFinally {
public static void main(String[] args) {
try{
throw new Exception("Simple Exception");
}catch(Exception e){
Logger.getLogger(IO.class.getName()).log(Level.SEVERE, null, e);
System.out.println(e.getMessage());
}finally{
System.out.println("Finally");
}
}
}

Objects
Abstarct car

package basics;
/**
* Abstract class (have abstract methods)
* @author Padaboo I.B. Aleksandrov
*/
public abstract class Car{
protected int speed;
protected String color;

/**
* constructor
*/
public Car(){
speed = 50;
}
/**
* overload
* @param color
*/
public Car(String color){
this.color = color;
}
/**
* A common method for all heirs
*/
public void drive(){
//do drive
}
/**
* a method that must be implemented in all heirs
*/
abstract boolean painting(String newColor);
/**
*
* @return int speed
*/
public int getSpeed(){
return speed;
}
/**
* a method that must be implemented in all heirs
*/
abstract void acceleration(int a);
}

Sport car
/*
*/
package basics;
/**
* Heir class abstract class car
* @author Padaboo I.B. Aleksandrov
*/
public class SportCar extends Car {
@Override
boolean painting(String newColor) {
color = newColor;
return true;
}
public void acceleration(int a) {
speed = speed * a;
}
}
/*
*/
package basics;
/**
* Heir class abstract class car
* @author Padaboo I.B. Aleksandrov
*/
public class SportCar extends Car {
@Override
boolean painting(String newColor) {
color = newColor;
return true;
}
public void acceleration(int a) {
speed = speed * a;
}
}

package basics;
/**
* Objects abstract extends protected
* @author padaboo I.B Aleksandrov
*/
public class Objects {
public static void main(String[] args) {

Car sportCar = new SportCar();

System.out.println(sportCar.getSpeed());

sportCar.acceleration(20);

System.out.println(sportCar.getSpeed());

}
}

Reflections
package basics;
import java.lang.reflect.Field;
/**
*
* @author padaboo I.B. Aleksandov
*/
public class Reflection {

public static void main(String[] args) throws ClassNotFoundException, InstantiationException,
IllegalAccessException {
//get class name
SportCar sc = new SportCar();

String name = sc.getClass().getName();

System.out.println(name);

//object from class name
Object rsc = (Object) Class.forName(name).newInstance();

System.out.println(rsc.toString());

//get class
Class csc = SportCar.class;

System.out.println(csc);

//get fields of super class
Field[] fields = SportCar.class.getSuperclass().getDeclaredFields();
for (Field field : fields) {
System.out.println(field.getName());
}
//https://docs.oracle.com/javase/tutorial/reflect/
}
}

Parametrization

package basics;
/**
* Java Parametrizations generic inner class example
* @author padaboo I.B. Aleksandrov
*/
public class Parametrization{

//https://docs.oracle.com/javase/tutorial/extra/generics/methods.html
public static void main(String[] args) {
Parametrization app = new Parametrization();

app.genericTest();

}

private void genericTest(){
GenericObj<String,Car> g = new GenericObj<String,Car>("Test",new SportCar());
}

class GenericObj<String,T extends Car> {
public String name;
public T car;
private GenericObj(String str, T carObj) {
car = carObj;
name = str;
}
}
}

Class path


package basics;
import java.io.File;
/**
* http://docs.oracle.com/javase/tutorial/essential/environment/sysprop.html
* @author padaboo I.B Aleksandrov
*/
public class ClassPath {
public static void main(String[] args) {
System.getProperty("java.class.path");
String classpath = System.getProperty("java.class.path");
String[] classpathEntries = classpath.split(File.pathSeparator);
for(String s: classpathEntries){
System.out.println(s);
}
}
}

IO



/*
<?xml version="1.0" encoding="UTF-8"?>
/>
/>
/>

/>

*/
package basics;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
/**
* https://docs.oracle.com/javase/tutorial/essential/io/scanning.html
* IO Java read file write file sample;
* @author Padaboo I.B. Aleksandrov
*/
public class IO {
String fileName = "iotest.xml";
String content;
String absoluteFilePath;
String workingDirectory;

public static void main(String[] args) throws IOException {
IO app = new IO();
app.workingDirectory = app.getworkingDirectory();
app.absoluteFilePath = app.workingDirectory + app.fileName;

app.content = app.readFile(app.absoluteFilePath);
app.content += "append";

app.writeFile(app.absoluteFilePath,app.content);
}

private String getworkingDirectory(){
return System.getProperty("user.dir") + File.separator + "src"+File.separator+
"basics"+File.separator;
}

private String readFile(String path) throws IOException{
BufferedReader br = new BufferedReader(new FileReader(path));
StringBuilder sb = new StringBuilder();
String line = br.readLine();
while (line != null) {
sb.append(line);
sb.append(System.lineSeparator());
line = br.readLine();
System.out.println(line);
}

br.close();
return sb.toString();
}

private void writeFile(String path,String str) throws IOException{
File file = new File(path);
FileWriter writer = new FileWriter(file);
writer.write(str);
writer.flush();
writer.close();
}
}

XML
/*
<?xml version="1.0" encoding="UTF-8"?>
/>
/>
/>

/>

*/
package basics;
import java.io.File;
import java.io.IOException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;
/**
* https://docs.oracle.com/javase/7/docs/api/javax/xml/xpath/package-summary.html
* https://docs.oracle.com/javase/tutorial/jaxp/sax/parsing.html
* Xml Xpath sample
* @author padaboo I.B. Aleksandrov
*/
public class XmlSample {

public static void main(String[] args) throws IOException, ParserConfigurationException,
SAXException {
String filePath = XmlSample.getworkingDirectory() + "iotest.xml";

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
factory.setNamespaceAware(true);
DocumentBuilder builder;
org.w3c.dom.Document doc = null;

builder = factory.newDocumentBuilder();
doc = (org.w3c.dom.Document) builder.parse(new File(filePath));
NodeList ltemsList = doc.getElementsByTagName("item");

for(int i=0; i<ltemsList.getLength() ; i++) {
Node itemNode = ltemsList.item(i);

System.out.println(itemNode.getAttributes().getNamedItem("level").getNodeValue());
}
}

public static String getworkingDirectory(){
return System.getProperty("user.dir") + File.separator + "src"+File.separator+
"basics"+File.separator;
}
}

System


Command line


package sys;
/**
* https://docs.oracle.com/javase/tutorial/essential/environment/cmdLineArgs.html
* @author padaboo I.B Aleksandrov
*/
public class CommandLineSample {
public static void main(String[] args){
if (args.length > 0) {
for (String s: args) {
System.out.println(s);
}
}
}
}

Execute

package sys;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
/**
* https://docs.oracle.com/javase/7/docs/api/java/lang/Runtime.html
* @author padaboo I.B. Aleksandrov
*/
public class ExecuteSample {
public static void main(String[] args) throws IOException, InterruptedException {
Process p = Runtime.getRuntime().exec("pwd");
p.waitFor();
BufferedReader reader = new BufferedReader(new InputStreamReader(p.getInputStream()));
String line = "";
while ((line = reader.readLine()) != null) {
System.out.println(line);
}
}
}

Key press


package sys;
import java.util.Scanner;
/**
* https://docs.oracle.com/javase/tutorial/essential/io/scanning.html
* @author padaboo I.B. Aleksandrov
*/
public class InScannerKeyPress {
public static void main(String[] args) {
Scanner keyboard = new Scanner(System.in);
boolean exit = false;

while (!exit) {
String input = keyboard.nextLine();
if(input != null) {
System.out.println("Your input is : " + input);
if ("quit".equals(input)) {
exit = true;
} else if ("x".equals(input)) {
}
}
}
keyboard.close();
}
}

Native Sample

package sys;
/**
*
* https://www3.ntu.edu.sg/home/ehchua/programming/java/JavaNativeInterface.html
* https://en.wikipedia.org/wiki/Java_Native_Interface
* @author padaboo I.B. Aleksandrov
*/
public class NativeSample {

public native void displayHelloWorld();
static{
System.loadLibrary("hello");
}
public static void main(String[] args){
/**
javac NativeSample.java
$ javah -classpath . NativeSample
$ gcc -shared -fPIC -I $JAVA_HOME/include -I $JAVA_HOME/include/linux Hello.cpp -o
hello.so
$ java -classpath . -Djava.library.path=. HelloWorld
Hello World!
*/
new NativeSample().displayHelloWorld();
}
}
/**
#include "HelloJNICppImpl.h"
#include using namespace std;
void sayHello () {
cout << "Hello World from C++!" << endl;
return;
}
*/
/**
#ifndef _HELLO_JNI_CPP_IMPL_H
#define _HELLO_JNI_CPP_IMPL_H
#ifdef __cplusplus
extern "C" {
#endif
void sayHello ();
#ifdef __cplusplus
}
#endif
#endif
*/

Threads


Thread

package threads;
/**
* https://docs.oracle.com/javase/7/docs/api/java/lang/Thread.html
* Java Threads
* @author Padaboo I.B. Aleksandrov
*/
public class ThreadSample{

public static void main(String[] args) {
ThreadSample app = new ThreadSample();
app.threadRun();
}

class MyThread extends Thread{

@Override
public void run() {
System.out.println("Run");
}
}

private void threadRun(){
MyThread t = new MyThread();
t.start();
}
}

Thread Sleep

package threads;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* https://docs.oracle.com/javase/tutorial/essential/concurrency/sleep.html
* Java thread sleep
* @author Padaboo I.B. Aleksandrov
*/
public class ThreadSleepSample {
public static void main(String[] args) {
ThreadSleepSample app = new ThreadSleepSample();
app.threadSleepTest();
}

private void threadSleepTest(){
Runnable r;
r = new Runnable() {
public void run() {
for (int i = 0; i < 9; i = i + 1){
try {
System.out.println("Run " + i);
Thread.sleep(500);
} catch (InterruptedException ex) {
Logger.getLogger(ThreadSleepSample.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
};
Thread t = new Thread(r);
t.start();
}
}

Thread Lock

package threads;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Lock;
/**
* https://docs.oracle.com/javase/tutorial/essential/concurrency/newlocks.html
* Java lock sample
* @author padaboo I.B. Aleksandrov
*/
public class ThreadLock implements Runnable{
private Lock lock;
public static void main(String[] args){
ThreadLock app = new ThreadLock();

}

@Override
public void run() {
try {
if(lock.tryLock(10, TimeUnit.SECONDS)){
//do
}
} catch (InterruptedException e) {
e.printStackTrace();
}finally{
//unlock
lock.unlock();
}
}
}

Thread Local

package threads;
/**
* Java ThreadLocal example
* https://docs.oracle.com/javase/7/docs/api/java/lang/ThreadLocal.html
* @author Padaboo I.B. Aleksandrov
*/
public class ThreadLocalSample implements Runnable {
ThreadLocal str = new ThreadLocal(){
@Override
protected String initialValue(){
return new String("Test");
}
};;

public static void main(String[] args){
ThreadLocalSample app = new ThreadLocalSample();

Thread t = new Thread(app);
t.start();
}
public void run() {
System.out.println(str.get());
}
}

Daemon thread

package threads;
/**
* https://docs.oracle.com/javase/7/docs/api/java/lang/Thread.html
* Java daemon thread
* @author Padaboo I.B Alelsandrov
*/
public class DaemonThread extends Thread{
public static void main(String[] args) throws InterruptedException {
DaemonThread t = new DaemonThread();
t.setDaemon(true);
t.start();

try {
Thread.sleep(3000);
} catch (InterruptedException x) {}
}

@Override
public void run() {
while (true) {
System.out.println("Daemon Run ");
try {
sleep(500);
} catch (InterruptedException e) {
// handle exception here
}
}
}
}

Runnable

package threads;
/**
* Java runnable threads
* @author padaboo I.B Aleksandrov
*/
public class RunnableSample implements Runnable{

public static void main(String[] args) {
RunnableSample run = new RunnableSample();
Thread t = new Thread(run);
t.start();
}
public void run() {
int i = 1;
while(i<=10){
System.out.println(i);
i++;
}
}
}

Runanble handler


package threads;
/**
* Java Runnable handler
* @author Padaboo I.B. Aleksandrov
*/
public class RunnableHandler {

public static void main(String[] args) {
RunnableHandler app = new RunnableHandler();
app.hadlerTest();
}

public void hadlerTest(){
Runnable handler = new Runnable(){
public void run() {
System.out.println("Run");
}
};

Thread t = new Thread(handler);
t.start();
}
}

Thread isInterrupted

package threads;
/**
* https://docs.oracle.com/javase/tutorial/essential/concurrency/interrupt.html
* @author padaboo I.B. Aleksandrov
*/
public class ThreadInterrupted extends Thread{
public static void main(String[] args){
ThreadInterrupted app = new ThreadInterrupted();
app.start();
}

public void run( ) {
int i = 0;
while (!isInterrupted( )) {
System.out.println("i:"+i);
i++;
}
}
}

Thread executors

package threads;
import java.util.concurrent.Executor;
/**
* https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/Executor.html
* Java Thread Executors
* @author padaboo I.B. Aleksandrov
*/
public class ExecutorsSample {

public static void main(String[] args) {
ExecutorsSample app = new ExecutorsSample();
app.executorsTest();
}

private void executorsTest(){
Executor executor = new Executor() {
public void execute(Runnable command) {
command.run();
}
};

Runnable command = new Runnable() {
public void run() {
System.out.println("Run");
}
};

executor.execute(command);
}
}

Thread executors services

package threads;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
/**
* Java Executor ExecutorService
* https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/ExecutorService.html
* @author Padaboo I.B. Aleksandrov
*/
public class ExecutorsServicesSample {
ExecutorService pool = Executors.newFixedThreadPool(2);
public static void main(String[] args) {
ExecutorsServicesSample app = new ExecutorsServicesSample();
app.ExecutorsServicesTest();
}

private void ExecutorsServicesTest(){
pool.execute(new Handler(1));
pool.execute(new Handler(2));
pool.shutdown();
}

class Handler implements Runnable {
private final int number;
Handler(int number) { this.number = number; }
public void run() {

System.out.println("Thread" + this.number);
}
}
}

Thread Callable Future

package threads;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
/**
* Java Callable Future Sample
* https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/Callable.html
* @author padaboo I. B. Aleksandrov
*/
class CallableFutureSample {
public static void main(String[] args) throws ExecutionException, InterruptedException{
CallableFutureSample app = new CallableFutureSample();
app.callableTest();
}

private void callableTest() throws ExecutionException, InterruptedException{
ExecutorService ex = Executors.newCachedThreadPool();

CallableThread call = new CallableThread();

Future future = ex.submit(call);
System.out.println(future.get());

ex.shutdown();
}

class CallableThread implements Callable{
public Integer call() throws Exception {
int i = 1;
return i;
}
}

}

Thread Count Down Latch

package threads;
import java.util.concurrent.CountDownLatch;
/**
*https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/CountDownLatch.html
* @author padaboo I.B. Aleksandrov
*/
public class CountDownLatchSample {

public static void main(String args[]) throws InterruptedException {
CountDownLatchSample app = new CountDownLatchSample();
app.CountDownLatchTest();
}

private void CountDownLatchTest() throws InterruptedException{
CountDownLatch startSignal = new CountDownLatch(1);
CountDownLatch doneSignal = new CountDownLatch(2);
for (int i = 0; i < 2; ++i) // create and start threads
new Thread(new Worker(startSignal, doneSignal)).start();
startSignal.countDown(); // let all threads proceed
doneSignal.await();
}
class Worker implements Runnable {
private final CountDownLatch startSignal;
private final CountDownLatch doneSignal;

private Worker(CountDownLatch startSignal, CountDownLatch doneSignal) {
this.startSignal = startSignal;
this.doneSignal = doneSignal;
}
public void run() {
try {
startSignal.await();
doWork();
doneSignal.countDown();
} catch (InterruptedException ex) {} // return;
}
void doWork() {
System.out.println("Work");
}
}
}

Scheduled Thread Pool

package threads;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
/**
* https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/ScheduledExecutorService.html
* @author Padaboo I.B. Aleksandrov
*/
public class ScheduledThreadPoolSample {
public static void main(String[] args) throws InterruptedException {
ScheduledThreadPoolSample app = new ScheduledThreadPoolSample();

}

private void ScheduledTest() throws InterruptedException{
ScheduledExecutorService scheduledThreadPool = Executors.newScheduledThreadPool(5);

for(int i=0; i<3; i++){
Thread.sleep(1000);
WorkerThread worker = new WorkerThread("Run");
scheduledThreadPool.schedule(worker, 10, TimeUnit.SECONDS);
}

//add some delay to let some threads spawn by scheduler
Thread.sleep(30000);

scheduledThreadPool.shutdown();
while(!scheduledThreadPool.isTerminated()){
//wait for all tasks to finish
}
System.out.println("Finished all threads");
}

public class WorkerThread implements Runnable{
private String command;
public WorkerThread(String str){
this.command = str;
}
@Override
public void run() {
processCommand();
}
private void processCommand() {
try {
Thread.sleep(5000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
@Override
public String toString(){
return this.command;
}
}
}

Thread synchronized


package threads;
/**
* Java syncronized
* @author Padaboo I.B. Aleksandrov
*/
public class ThreadSyncSample{
Sync synchObj;

public static void main(String[] args){
ThreadSyncSample app = new ThreadSyncSample();
app.syncTest();
}

private void syncTest(){
synchObj = new Sync();

Runnable r = new Runnable() {
public void run() {
//synchronized method
synchObj.plus();
System.out.println("synchronized method" + synchObj.getJ());
}
};
Thread t = new Thread(r);
t.start();
}
class Sync{
int j = 1;

public synchronized void plus(){
j++;
}

public synchronized int getJ(){
return j;
}

public void syncTest(){
synchronized (this) {
System.out.println("notifyAll");
this.notifyAll();
}
}
}
}

Net



Client socket

package net;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.Socket;
/**
* https://docs.oracle.com/javase/tutorial/networking/sockets/readingWriting.html
* @author Padaboo I.B. Aleksandrov
*/
public class ClientSocketSample {
public static void main(String[] args) throws Exception {

Socket s = new Socket("127.0.0.1", 8080);
BufferedReader input =
new BufferedReader(new InputStreamReader(s.getInputStream()));

String answer = input.readLine();
System.out.println(answer);
System.exit(0);
}
}

Server socket

package net;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Date;
/**
* https://docs.oracle.com/javase/tutorial/networking/sockets/clientServer.html
* @author padaboo I.B. Aleksandrov
*/
public class ServerSocketSample {
public static void main(String[] args) throws Exception {
ServerSocket listener = new ServerSocket(8080);
try {
while (true) {
Socket socket = listener.accept();
try {
PrintWriter out =
new PrintWriter(socket.getOutputStream(), true);
out.println(new Date().toString());
} finally {
socket.close();
}
}
}
finally {
listener.close();
}
}
}

Thread server

package net;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* Thread Server messages
* @author Padaboo I.B. Aleksandrov
*/
public class ThreadServerSample {
public static void main(String[] args){
ThreadServerSample app = new ThreadServerSample();
try {
app.startUp();
} catch (IOException ex) {
Logger.getLogger(ThreadServerSample.class.getName()).log(Level.SEVERE, null, ex);
}

}

private void startUp() throws IOException{
ServerSocket sock = new ServerSocket(8080);
int i = 1;

while(true){
Socket in = sock.accept();
Runnable r = new ThreadServer(in);
Thread t = new Thread(r);
t.start();
}
}

class ThreadServer implements Runnable{
Socket in;

private ThreadServer(Socket in) {
this.in = in;
}

public void run() {
try {
InputStream inStream = in.getInputStream();
OutputStream outStream = in.getOutputStream();

Scanner in = new Scanner(inStream);

PrintWriter out = new PrintWriter(outStream);

while(in.hasNextLine()){
String line = in.nextLine();
out.println(line);
}

} catch (IOException ex) {
Logger.getLogger(ThreadServerSample.class.getName()).log(Level.SEVERE, null, ex);
}
}
}

}
Url sample

package net;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.URL;
/**
* https://docs.oracle.com/javase/tutorial/networking/urls/readingURL.html
* @author padaboo I.B. Aleksandrov
*/
public class UrlSample {

public static void main(String[] args) throws Exception {
URL oracle = new URL("http://192.168.0.101/");
BufferedReader in = new BufferedReader(
new InputStreamReader(oracle.openStream()));
String inputLine;
while ((inputLine = in.readLine()) != null)
System.out.println(inputLine);
in.close();
}
}

Mysql jdbc

package jdbcmysql;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
/**
* jdbc mysql example (have a dump file)
* Connector http://dev.mysql.com/downloads/connector/j/
* Statement https://docs.oracle.com/javase/tutorial/jdbc/basics/processingsqlstatements.html
* Prepared http://docs.oracle.com/javase/tutorial/jdbc/basics/prepared.html
* @author Padaboo I.B Aleksandrov
*/
public class MysqlConnectSample {

public static void main(String[] args) throws Exception {
Connection conn = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/jdbctest","root",
"");

String query = "SELECT * FROM jdbctest.Users;";

//execute mysql procedure
//CallableStatement stmt;
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery(query);
//stmt.executeUpdate(sql);
ResultSetMetaData md = rs.getMetaData();

System.out.println("count " + md.getColumnCount());

while (rs.next()) {
int id = rs.getInt("id");
System.out.println(id);
}
rs.close();
}
}

Dump

CREATE DATABASE `jdbctest` CHARACTER SET utf8 COLLATE utf8_general_ci;
CREATE TABLE `jdbctest`.`Users` (
`id` INT NOT NULL AUTO_INCREMENT,
`name` VARCHAR(128) NULL,
`session_key` VARCHAR(128) NULL,
`email` VARCHAR(128) CHARACTER SET 'utf8' COLLATE 'utf8_general_ci' NULL,
`password` VARCHAR(128) NULL,
`activation_key` VARCHAR(128) CHARACTER SET 'utf8' COLLATE 'utf8_general_ci' NULL,
PRIMARY KEY (`id`));
INSERT INTO `jdbctest`.`Users` (`name`, `session_key`, `email`, `password`, `activation_key`)
VALUES ('ivan2', 'asdasddd', 'jetananas@yandex.ru', 'asdasad', 'asaadads');
INSERT INTO `jdbctest`.`Users` (`name`, `session_key`, `email`, `password`, `activation_key`)
VALUES ('ivan1', 'asdasddd', 'jetananas@yandex.ru', 'asdasad', 'asaadads');



PDF
Исходники
java
–24
~2900
  Иван (@Padaboo)

комментарии (9)

+4
MyFutureIsYou ,   * (был изменён)
зачем? вот так все скопом без форматирования и какой-то связи
–5
Padaboo ,  
Привет. C форматированием, приложил исходники и pdf.
+3
bromzh ,  

Это чтобы типа как книга была?
Да чо уж там, надо было в jpeg закинуть. Хранить исходники в виде текста на специализированных для таких вещей сайтах в 2017 году — моветон.

0
Padaboo ,  
поправил, point
+5
nesterione ,  
Вам не кажется, что место всему этому github или gist в лучшем случае? Смысл вставлять куски кода без какой либо цели и описания? Кто знает java, тому всё это не нужно, кто не знает, вряли ли будет большое удовольствие смотреть на всё это
+1
+2 –1
Borz ,  

забыли рубрику "Я пиарюсь" указать. И да, это не "tutorial"

+2
+3 –1
shapovalex ,  
У меня только два вопроса:
— Что это?
— Зачем это здесь?
–3
Padaboo ,  
Это набор примеров, это должно быть именно тут.
0
TheRealDoge ,   
//long 8byte -9223372036854775808 -9223372036854775807
long l = 1;

//byte 1byte -128 до 127
byte b = 1;

//float 4byte +-3,40282347E+38F
float f = 0.1f;

У вас на 3 комментария, 3 разных стиля записи диапазона.