LESS TALK, MORE CODE: java basics

Showing posts with label java basics. Show all posts

Tuesday

Dynamically calling a class - method in java by using reflection

Dynamically call a method on a dynamically given class by using reflection:

import java.lang.reflect.Method;

try {
       String myClassName = "tr.com.xx.xx.xx.Example";
       String myMethodName = "exampleMethod";

       Class<?> myClassRef = Class.forName(myClassName);
       Object instanceOfMyClass = myClassRef.newInstance();
       
       //my object input types in order: param1(int), param2(String), param3(MyDTO), param4(List<MyDTO>)
       Method method = myClassRef.getDeclaredMethod(myMethodName, int.class, String.class, MyDTO.class, List.class);
       MyResult respoonse = (MyResult) method.invoke(instanceOfMyClass, param1, param2, param3, param4);
       System.out.println("response" + response.getX());

} catch(Exception e) {
       //logging
       System.out.println(e.getMessage());

Why is SimpleDateFormat changing given date?

//The upper case Y is "week year". It has 364 or 371 days 
//The lower case y has usual 365 or 366.
//So they give different outputs:
//Locale.forLanguageTag("tr_TR") >> comes with Java 7

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;


public class Test {

    public static void main(String[] args) {
       try {
           String dateString = new java.util.Date().toString();
           System.out.println(dateString);

           SimpleDateFormat format = new SimpleDateFormat("EEE MMM dd HH:mm:ss z yyyy", Locale.forLanguageTag("tr_TR"));
           Date date = format.parse(dateString);
           System.out.println(date.toString());

           SimpleDateFormat format2 = new SimpleDateFormat("EEE MMM dd HH:mm:ss z YYYY", Locale.forLanguageTag("tr_TR"));
           Date date2 = format2.parse(dateString);
           System.out.println(date2.toString());

       } catch (ParseException e) {
           //log
       }
    }
    
}

Output:

Mon May 14 10:31:14 EEST 2018
Mon May 14 10:31:14 EEST 2018
Mon Jan 01 09:31:14 EET 2018

Friday

Sort list of strings by using Localization

import java.text.Collator;

List<String> yourValues = …;
Collections.sort(yourValues, Collator.getInstance(Locale.forLanguageTag("your locale ")));

See Collator interface.

Join ArrayList String elements into a single String with a separator

Download commons-lang3-3.0.1.jar.

https://mvnrepository.com/artifact/

org.apache.commons/commons-lang3/3.0.1

For maven:

<groupId>org.apache.commons</groupId>

<artifactId>commons-lang3</artifactId>

</dependency>

import java.util.ArrayList;

import java.util.List;

import org.apache.commons.lang3.StringUtils;

public class Test {

public static void main(String[] args) {

List<String> list = new ArrayList<String>();

list.add("less");

list.add("talk");

list.add("more");

list.add("code");

System.out.println(StringUtils.join(list, ", "));

}

OUTPUT:

less, talk, more, code

Tuesday

Get URL content

import java.io.BufferedReader;

import java.io.BufferedWriter;

import java.io.File;

import java.io.FileWriter;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.net.MalformedURLException;

import java.net.URL;

import java.net.HttpURLConnection;

public class Test {

public static void main(String[] args) {

BufferedWriter bw = null;

BufferedReader br = null;

String inputLine;

try {

//If you are behind a proxy you should set the following settings.

//You can look my other post to learn your own proxy infos

// System.setProperty("http.proxyHost", "your proxy host");

// System.setProperty("http.proxyPort", "your proxy port");

URL url = new URL("http://lesstalkmorecode.blogspot.com.tr/");

HttpURLConnection conn = (HttpURLConnection) url.openConnection();

conn.setReadTimeout(10*1000);

conn.setConnectTimeout(5*1000);

InputStream in = conn.getInputStream();

br = new BufferedReader(new InputStreamReader(in));

String fileName = "/users/content.html";

File file = new File(fileName);

if (!file.exists())

file.createNewFile();

FileWriter fw = new FileWriter(file.getAbsoluteFile());

bw = new BufferedWriter(fw);

while ((inputLine = br.readLine()) != null)

bw.write(inputLine);

} catch (MalformedURLException e) {

//log

} catch (IOException e) {

//log

} finally {

try {

if(bw != null)

bw.close();

if(br != null)

br.close();

} catch (IOException e) {

//log

}

View your proxy settings

Open Google Chrome enter below address in the bar:

chrome://net-internals/#proxy

Open cmd, write >> ipconfig /all

See >> Windows IP Configuration >> Primary Dns Suffix

Open Internet Explorer

Internet Options >> Connections >> LAN Settings
See from the pop-up address bar

Open Mozilla Firefox enter below address in the bar:

about:preferences#advanced

Friday

Check if a web service is accessible? Ping a host for availability.

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