Category Archives: Java

Json: sending/receiving Binary Data

You cannot just send raw binary data in JSON. You need to do a conversion first. The general way to encode binary data to a String is to use an implementation of Base64 encoding. Encode: String Base64.encodeToString(byteArray, Base64.DEFAULT); Decode: byte … Continue reading

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Death of Singleton? Rise of Dependency Injection?

Was researching on the Singleton pattern and most articles on stack overflow were negative on the Singleton. link.  What I got out of the discussions is that it’s really bad for developers who do TDD (test driven development). In the … Continue reading

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Eclipse Shortcut: Open any file quickly without browsing for it (Ctrl + Shift + R)

I was watching Google IO videos and wondering how they could search and open file without using the package explorer. Turns out they were using this shortcut to find and open files. It’s really handy when you know the name … Continue reading

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Addition, Subtraction, Multiplication using bit operators

The key for addition is to think about how numbers the carry works. You want to get the sum without worrying about caring, and then sum first (XOR), and then worry about the carry bit (AND << 1). // Iterative … Continue reading

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Java: Comparator

Writing a Comparator for Integer for use with Arrays.sort: Arrays.sort(Integer[], new Comparator<Integer>() { public int compare(Integer a, Integer b) { if (function(a) != function(b)) return function(a)-function(b); } } Normal compare return values: if (a < b) return -1; if (a … Continue reading

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Java: Quick Way to initialize arrays

Instead of: for (i = 0; i < array.length; i++) array[i] = <initValue> One can just do: Arrays.fill(array,<initValue>); Works for String[] at least.  

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Java: ArrayList.toArray() usage shortcut

Saw this pretty neat shortcut to get a List<T>[] to T[]. Usage: List<String> res = new ArrayList<String>(); String[] result = res.toArray(new String[res.size()]);  I had originially seen this: String[] result = res.toArray(new String[0]);  But supposedly using res.size() is better. StackOverflow

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Regular Expressions

“1+1=2” How do I use Java’s String.split so + and = will be matched on? Regular Expression : \\+|= Forgot about the existence of the OR |. public static final String EQUATION_TEST = “1+1=2”; String[] str = EQUATION_TEST.split(“\\+|=”); System.out.println(“EQUATION_TEST.split=”+str.length);// Should … Continue reading

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Java: JDBC Basics

Running through this tutorail: http://docs.oracle.com/javase/tutorial/jdbc/basics/index.html Used JDBC before at Northrop figuring it out with working knowledge but never really went through a tutorial for it. Nice thing about the tutorial is that it populates a DB with data for you … Continue reading

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