Linux: RPM

Here is couple of functions I use when working with RPM packages:


Show containing "postg"

rpm -qa | grep postg

Show top 20:

rpm -qa | tail -20

Install package:

rpm -ivh somed-1.0.0.armv7l

Uninstall:

rpm -e somed-1.0.0.armv7l

Linux: RPM

Here is couple of functions I use when working with RPM packages:


Show containing "postg"

rpm -qa | grep postg

Show top 20:

rpm -qa | tail -20

Install package:

rpm -ivh somed-1.0.0.armv7l

Uninstall:

rpm -e somed-1.0.0.armv7l

Java Map interface

In this tutorial we will discuss various implementations of Java Map interface. Java Map is one of the most commonly used datatypes when you want to store items by key.

HashMap

HashMap should be only used when the objects we store as KEYS have implemented the method hashCode in such way that it give unique key for a given object.

 @Override public int hashCode() {

Let's say we have an object USCitizen

name,
socialSecurityNumber


Map myMap = new HashMap();

Java Map interface

In this tutorial we will discuss various implementations of Java Map interface. Java Map is one of the most commonly used datatypes when you want to store items by key.

HashMap

HashMap should be only used when the objects we store as KEYS have implemented the method hashCode in such way that it give unique key for a given object.

 @Override public int hashCode() {

Let's say we have an object USCitizen

name,
socialSecurityNumber


Map myMap = new HashMap();

Java: RegEx: WebSpider

In this tutorial we will create a basis for a WebSpider program that fetches all links from the given Web page, checks which have extensions of interest and downloads these files.

The result of the app will be a folder with Google Earth map overlays:

/Users/uki/Desktop/KMZ

├── 1.kmz

├── 10.kmz

├── 11.kmz

├── 12.kmz

├── 13.kmz

├── 14.kmz

├── 15.kmz

├── 16.kmz

├── 17.kmz

├── 18.kmz

We will use basic java networking classes:

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.net.URL;

and regular expressions:

ublic class RegExConstants {

   /**    * @param extensions    * @return    *  (                -- start of main grouping    *     [^\s]+        -- must contains one, or many strings (but not white space)    *     (             -- start of extension grouping    *        \.         -- existence of a dot, eg.: .kmz    *        (?i)       -- NOT case sensitive for the next group    *        (kmz|kml)  -- kmz OR kml strings    *     )$            -- should exist on the end    *  )                -- end of main grouping    */   public static String fileExtensionPattern(String[] extensions) {

      StringBuilder sb = new StringBuilder("");

      if (extensions.length > 0) {
         int n = 0;
         for (String extension : extensions) {
            if (n > 0) {
               sb.append("|"); // append OR            }
            sb.append(extension);
         }
      }
      String pattern = "([^\\s]+(\\.(?i)(" + sb.toString() + "))$)";
      System.out.println("fileExtensionPattern: " + pattern);
      return pattern;
   }

   public static final String anchorTagPattern = "<a *href=\"(.+?)</a>";
   public static final String urlPattern = "(https?|ftp|file)://[-a-zA-Z0-9+&@#/%?=~_|!:,.;]*[-a-zA-Z0-9+&@#/%=~_|]";
}