If you are developing a Java project in Eclipse under a linux system, you may want to remote access the project from another location. You can remote desktop the linux box by using teamviewer, but sometimes that can be very slow. You can also edit, compile and execute your Java project from a regular ssh terminal. Using terminal to edit, compile and run your remote eclipse project is often faster. This post shows you how to compile and run eclipse project in terminal.
Basics
Java Remove Element from ArrayList
To remove some elements from an ArrayList while iterating over the ArrayList, we need to use Iterator. Integer[] arr = {1,2,3,4,5,6}; ArrayList<Integer> list = new ArrayList<Integer>(Arrays.asList(arr)); System.out.println(list); Iterator<Integer> iter = list.iterator(); while(iter.hasNext()){ int i = iter.next(); if(i==5) iter.remove(); } System.out.println(list);Integer[] arr = {1,2,3,4,5,6}; ArrayList<Integer> list = new ArrayList<Integer>(Arrays.asList(arr)); System.out.println(list); Iterator<Integer> iter = list.iterator(); … Read more
How Developers Sort in Java?
While analyzing source code of a large number of open source Java projects, I found Java developers frequently sort in two ways. One is using the sort() method of Collections or Arrays, and the other is using sorted data structures, such as TreeMap and TreeSet.
Compile and Run Java in Command Line with External Jars
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
Java Serialization
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
Java Varargs Examples
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
How to Calculate Time Difference in Java?
Given two strings of time, you may want to calculate the difference between them. The following provide a simple solution. import java.text.SimpleDateFormat; import java.util.Date; public class Main { public static void main(String[] args) throws Exception{ String time1 = "12:00:00"; String time2 = "12:01:00"; SimpleDateFormat format = new SimpleDateFormat("HH:mm:ss"); Date date1 = format.parse(time1); Date … Read more
Java Enum Examples
An enum in Java is just like any other class, with a predefined set of instances. Here are several examples to highlight how to use Java Enum. 1. Simple Example public enum Color { RED, YELLOW, BLUE; //each is an instance of Color }public enum Color { RED, YELLOW, BLUE; //each is an instance of … Read more
Deep Understanding of Arrays.sort()
Arrays.sort(T[], Comparator < ? super T > c) is a method for sorting user-defined object array. The official Java Doc briefly describe what it does, but not much for deep understanding. In this post, I will walk though the key information for deeper understanding of this method. 1. How to Use Arrays.sort(): A Simple Example … Read more
Top 9 questions about Java Maps
In general, Map is a data structure consisting of a set of key-value pairs, and each key can only appears once in the map. This post summarizes Top 9 FAQ of how to use Java Map and its implemented classes. For sake of simplicity, I will use generics in examples. Therefore, I will just write Map instead of specific Map. But you can always assume that both the K and V are comparable, which means K extends Comparable and V extends Comparable.
Java hashCode() and equals() Contract for the contains(Object o) Method of Set
The article is about hashCode and equals contract used for the contains(Object o) method in Set.
The substring() Method in JDK 6 and JDK 7
The implementation of the substring(int beginIndex, int endIndex) method in JDK 6 is different from JDK 7. This post explains the differences. For simplicity reasons, the substring() method represents the substring(int beginIndex, int endIndex) method in this post.