This line is throwing anNPE, producing an IllegalStateException in the exception chain: as you don’t initialize stopPort (or startPort) in your onCreate method. You should have something like: The statement simply declares the variable which is null by default. Only instances that have been instantiated can have their methods invoked.
Use the (excellent) JSON-Java library from json.org then toString can take a second argument to provide the name of the XML root node. This library is also able to convert XML to JSON using XML.toJSONObject(java.lang.String string) Check the Javadoc Link to the the github repository POM original post updated with new links
Using the generified version of class Class allows you, among other things, to write things like and then you can be sure that the Class object you receive extends Collection, and an instance of this class will be (at least) a Collection.
This is how you can do it. This code assumes the existance of a buffered image called ‘image’ (like your comment says)
An Iterable is a simple representation of a series of elements that can be iterated over. It does not have any iteration state such as a “current element”. Instead, it has one method that produces an Iterator. An Iterator is the object with iteration state. It lets you check if it has more elements using hasNext() and move to the next element … Read more
If the directory doesn’t exist you need to create it. Java won’t create it by itself since the File class is just a link to an entity that can also not exist at all. As you stated the error is that the file cannot be created. If you read the documentation of PrintWriter constructor you can see … Read more
Short answer: Explanation: (based on this question about LocalDate) Despite its name, java.util.Date represents an instant on the time-line, not a “date”. The actual data stored within the object is a long count of milliseconds since 1970-01-01T00:00Z (midnight at the start of 1970 GMT/UTC). The equivalent class to java.util.Date in JSR-310 is Instant, thus there are convenient methods to provide the conversion to and fro: … Read more
You have to do a few things: define a new variable JAVA_HOME and assign to it exactly JDK installation location, like C:\java\jdk_1.8.0 update your Path variable with: %JAVA_HOME%\bin important point set it first to Path.Finally, your Path will look: %JAVA_HOME%\bin;C:\Program Files\Common Files\Oracle\Java\javapath;C:\Program Files\Common Files\Microsoft Shared\Windows open console and type: java -version The output should be something like: BTW your Path has some duplication. Just remove an unneeded part.
The basic paradigm in Java is that you write classes, and that those classes are instantiated. Instantiated objects (an instance of a class) have attributes associated with them (member variables) that affect their behavior; when the instance has its method executed it will refer to these variables. However, all objects of a particular type might … Read more
Take a look here: Understanding Instance and Class Members When a number of objects are created from the same class blueprint, they each have their own distinct copies of instance variables. (…) Sometimes, you want to have variables that are common to all objects. This is accomplished with the static modifier. Fields that have the static modifier … Read more