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We suppose that we have have a java.io.InputStream object, how can you process that object and produce a String ? to anser this question, lets see the following example : I will Suppose that I have an InputStream that contains text data, and I want to convert it to a String. What is the easiest […]
On the Windows taskbar, right-click the Windows icon and select System. In the Settings window, under Related Settings, click Advanced system settings. 3. On the Advanced tab, click Environment Variables. 4. Click Edit to modify an existing environment variable. 5. After creating or modifying the environment variable, click Apply and then OK to have the change take effect. Information ! If you don’t have JAVA_HOME […]
synchronized methods enable a simple strategy for preventing thread interference and memory consistency errors: if an object is visible to more than one thread, all reads or writes to that object’s variables are done through synchronized methods. The synchronized keyword is all about different threads reading and writing to the same variables, objects and resources. […]
Which is more efficient for non-threaded applications? There are several differences between HashMap and Hashtable in Java: Hashtable is synchronized, whereas HashMap is not. This makes HashMap better for non-threaded applications, as unsynchronized Objects typically perform better than synchronized ones. Hashtable does not allow null keys or values. HashMap allows one null key and any number of null values. One of HashMap’s subclasses is LinkedHashMap, so in the event that you’d want predictable iteration order […]
1. Historic In the early 1990s, Sun was working on a project to design simple, high-performance software that ran in Personal Digital Assistant (PDAs). The C ++ language was chosen for the programming of this software, but the C language proved to be inefficient, especially with regard to security and ease of use. We therefore […]
Parameters and local variables are allocated on the stack (with reference types, the object lives on the heap and a variable in the stack references that object on the heap). The stack typically lives at the upper end of your address space and as it is used up it heads towards the bottom of the address space (i.e. towards zero). Your process also […]
We suppose that we have a text and we want to save this text inside a file using Java. To do this we can use the PrintWriter , lets see the following solution : Then, write your String to it, just like you would to any output stream : Be sure to call out.close() when […]
To read a Response body from a Post Request , JAX-RS provide response.readEntity(String.class). The next example is tested with Jersey 3.x Below is a JAX-RS POST request endpoint to accept a JSON input and return a JSON response. So the question here is how to read the response body from a post request ? Solution […]
In this Topic we will try to simulate the java.lang.OutOfMemoryError !! We will create an object holding 1MB of bytes, add it into a List, and repeat the create and add process until the JVM throw OutOfMemoryError. java.lang.OutOfMemoryError: Java heap space This example will run a while then it will throws java.lang.OutOfMemoryError. The Output : […]
In This post we will show you and example of Hello World using Java Swing . We will configures a JFrame and attach a JLabel to display a “hello world” centered in the JLabel component. The output : Also read : Java Basics
In this tutorial , we will show a Java 8 example of how to convert from Instant to ZonedDateTime So the output will be : If we need to convert from ZonedDateTime to Instant The output will be : Also read : How to convert String to Date in Java ? References : JavaDoc mkYong
In this tutorial, we will show you how to convert a String to java.util.Date. Many Java beginners Always find this problem of Date conversion. so we decided to post this solution !! let understand how to convert String Date in JAVA. java.text.SimpleDateFormat provide many date and time patterns : Letter Description Examples y Year 2013 […]
In this tutorial , we will see how we can get the extension of file in Java. In the next example , we will use lastIndexOf to get the file extension of a file. The above process, will fail if the directory name or file path includes a dot or double dots AND the file […]
In this tutorial , we will see how we can convert file to path using Java ? The java.nio.file package includes Java virtual machine interfaces and classes for accessing files, file attributes, and file systems. Convert File to Path If we want to convert from java.io.File to java.nio.file.Path we can use toPath() Convert Path to […]
Java Map : There are no duplicate values allowed in the map. A map object’s keys must be unique. HashMap, TreeMap, and LinkedHashMap are three groups that implement the Map interface in the Java collection system. SortedMap is a special interface for keeping all of the elements sorted. HashMap vs LinkedHashMap The ordering of the […]
Iterate a list in Java : in this Post we will discover different ways to browse a list in Java. (ArrayList) List.toString() If we want to iterate over a list in java , we can do that by converting the list to a string using the toString() function, then outputting it Output : Using For […]
ArrayList vs LinkedList : Both ArrayList and LinkedList implement the List interface, but what’s the difference then ? The main difference between ArrayList and LinkedList is in ArrayList which is implemented using an extensible array. As more items are added to ArrayList, its size dynamically increases. Its elements can be accessed directly using the get() […]
We’ll show you how to write a Comparator to sort a List using Java 8 Lambda expressions in this example. Classic Comparator example Lambda expression equivalent. Sort without Lambda A comparison of Developer objects based on their age is an example. Normally, you use Collections.sort and pass an anonymous Comparator class like this : Output […]
Minimum number of increment, We’ve been given an array of n components. You can choose any one element and increase the rest of the n-1 elements by one at each operation. You must make all elements equal and replicate the process as many times as you like. Determine the smallest number of operations required. Examples: […]
List<Integer> to int[] To convert List<Integer> to int[] in java we can use les Streams, With Java 8, int[] can be converted to Integer[] easily : Integer[] is generally not a good map key, as others have said. However, we now have a reasonably clean and native code in terms of conversion. Also read , […]