The following example shows how to compile and run Java program in command line mode with external jars. It is developed under Linux. 1. Compile & Run Java Program Without External Jar Let’s create a simple hello world program “helloworld.java”. public class helloworld{ public static void main(String[] args){ System.out.println("Hello!"); } }public class helloworld{ public static … Read more
Assuming you have created a dynamic web project under Eclipse, and you have tested your project, now you want to deploy the Spring project to a live server. The project runs on Tomcat and it interacts with MySQL database. How to correctly deploy your project? To deploy the project, you need to build a .war … Read more
You may often get error messages like “missing subfigure.sty”, “missing url.sty”, or missing other .sty files. The problem is caused by missing packages. This post outlines the steps to correctly install latex on Ubuntu latest version 14.04LTS. It should also work for most previous other versions. 1. Install Latex on Ubuntu In the terminal, type … Read more
As a web project runs on an HTTP server, a new server should be setup to hold the web project. Download Tomcat 7.0 here. Download the core Zip version, and unzip it to a directory (remember this directory). In your eclipse, create a new Server. Select the directory where you unzipped the tomcat. Run the … Read more
Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses. For example, given n = 3, a solution set is: “((()))”, “(()())”, “(())()”, “()(())”, “()()()” Java Solution 1 – DFS This solution is simple and clear. In the dfs() method, left stands for the remaining number of (, right stands … Read more
You may want to dump all public repositories from Github. First you need to get the list of the names of repositories. The following code can do that for you. There is a limit of number of requests from one machine. So you may want to create a token first, to raise the limit, so … Read more
To convert a Stream to an array, there is an overloaded version of toArray() method for Stream objects. The toArray(IntFunction<A[]> generator) method returns an array containing the elements of this stream, using the provided generator function to allocate the returned array. String[] stringArr = { "a", "b", "c", "d" }; Stream<String> stream = Stream.of(stringArr); String[] … Read more
This post shows how to add Java 8 support to eclipse Kepler. You can following the 3 simple steps to get Java 8 work on your existing Kepler on Mac. 1. Install Java 8 To download Java SE Development Kit 8, select the correct version for Mac here. It is a .dmg file which can … Read more
What is Serialization? In Java, object serialization means representing an object as a sequence of bytes. The bytes includes the object’s data and information. A serialized object can be written into a file/database, and read from the file/database and deserialized. The bytes that represent the object and its data can be used to recreate the … Read more
This article illustrates how to do a Spring Hello World by using Eclipse and Maven. You should install eclipse and maven plugin first. 1. Set up a Maven Project Create a Maven project by using the Wizard. GroupId identifies the project uniquely across all projects, so we need to enforce a naming schema. ArtifactId is … Read more
You may tried to install Maven plugin for eclipse and failed. The problem may be caused by the version. So to solve the problem, you can download a latest version of eclipse. The following shows how I install maven plugin for eclipse under Ubuntu. For Windows platform, it should be the same. Download Eclipse Kepler … Read more
Assuming you have the following list: List<String> list = Arrays.asList("a", "b", "c", "d", "e", "f");List<String> list = Arrays.asList("a", "b", "c", "d", "e", "f"); if you want to do something by using each element in a collection, there are two ways: 1) list.forEach(s -> System.out.println(s));list.forEach(s -> System.out.println(s)); 2) for(String s: list){ System.out.println(s); }for(String s: list){ System.out.println(s); … Read more
iterator often cause problems, because developers often do not know how it works. The following code is from source code of ArrayList. One common problem is throwing java.util.ConcurrentModificationException. This exception is actually throw in the remove method. remove() has to be called after next(). if remove() is called before next(), the size of arraylist changes, … Read more
1. What is Varargs in Java? Varargs (variable arguments) is a feature introduced in Java 1.5. It allows a method take an arbitrary number of values as arguments. public static void main(String[] args) { print("a"); print("a", "b"); print("a", "b", "c"); } public static void print(String … s){ for(String a: s) System.out.println(a); }public static void … Read more
If you want to install Pandas on Linux (Ubuntu, Redhat, etc.), but you don’t have root access, the installation may take a while. This is just record how I did it. After trying various kinds of different ways, I finally use one command to install it. Download Anaconda: http://continuum.io/downloads Change the download .sh file to … Read more