How to compare strings in Java?
String comparison in Java == performs a reference equality check, whether the 2 objects (strings in this case) refer to the same object in the memory. The equals() method will …
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Repeating a string using StringBuilder
Suppose you have the string ‘qwe’ and you need to repeat string ‘n’ times. Here’s how to do it with StringBuilder: Using StringBuilder and loop
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int n = 3; String in = "qwe"; StringBuilder b = new StringBuilder(n * in.length()); for (int i = 0; i < n; i += 1) { b.append(in); } String newString = b.toString(); |
How to add local jar files to a Maven project?
Imagine that you have implemented your java jar library and you need to connect it. Here are some examples of how to do it.
Read MoreHow to print a java array
Since Java 5 you can use Arrays.toString(arr) or Arrays.deepToString(arr) for arrays within arrays. Note that the Object[] version calls .toString() on each object in the array. The output is even …
Read MoreHow to parse JSON in Java
Google GSON library Let’s assume you have a class Book with just a title.
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private class Book { public String title; public Book(String title) { this.title = title; } } |
Create maven project and add dependencies.
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<dependency> <groupId>com.google.code.gson</groupId> <artifactId>gson</artifactId> <version>2.8.5</version> </dependency> |
Then write this code to transform JSON into class: …
Read MoreCode style examples from top java development companies
I decided to collect code style examples from the well-known company in the java community. There are both direct links to setting up the checkstyle and examples of setting the …
Read MoreHow to generate word document with apache poi
Today we will continue the topic of generating office documents from the template. To generate a docx document, we use the apache poi library.
Read MoreCheckstyle configuration in maven
What most annoying programmers besides reading someone else’s code? That’s right, formatting! In a large team it is difficult to impart to everyone the same requirements for the style of …
Read MoreWriting forEach with java 8 lambda
Let’s take a simple example. It’s easier, probably, and can not be – create a list of numbers and display it on the screen through the simplest cycle:
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List <Integer> numbers = Arrays.asList (1, 2, 3, 4, 5, 6); for (int number: numbers) { System.out.println (number); } |