Tutorial by Examples: int

Declaration of an interface using the interface keyword: public interface Animal { String getSound(); // Interface methods are public by default } Override Annotation @Override public String getSound() { // Code goes here... } This forces the compiler to check that we are overri...

Collect with toList() and toSet() Elements from a Stream can be easily collected into a container by using the Stream.collect operation: System.out.println(Arrays .asList("apple", "banana", "pear", "kiwi", "orange") .stream() .filter...

A Java class can implement multiple interfaces. public interface NoiseMaker { String noise = "Making Noise"; // interface variables are public static final by default String makeNoise(); //interface methods are public abstract by default } public interface FoodEater { ...

An interface can extend another interface via the extends keyword. public interface BasicResourceService { Resource getResource(); } public interface ExtendedResourceService extends BasicResourceService { void updateResource(Resource resource); } Now a class implementing ExtendedR...

When we create any View in layout, we can use the android:onClick attribute to reference a method in the associated activity or fragment to handle the click events. XML Layout <Button android:id="@+id/button" ... // onClick should reference the method in your activity or fra...

Integers are typically stored in a resource file named integers.xml, but the file name can be chosen arbitrarily. Each integer is defined by using an <integer> element, as shown in the following file: res/values/integers.xml <?xml version="1.0" encoding="utf-8"?> &...

In order to define an integer array write in a resources file res/values/filename.xml <integer-array name="integer_array_name"> <item>integer_value</item> <item>@integer/integer_id</item> </integer-array> for example res/values/arrays.xm...

From the documentation: The exception that is thrown when an application attempts to perform a networking operation on its main thread. This is only thrown for applications targeting the Honeycomb SDK or higher. Applications targeting earlier SDK versions are allowed to do networking on their ma...

You can as well access other interface methods from within your default method. public interface Summable { int getA(); int getB(); default int calculateSum() { return getA() + getB(); } } public class Sum implements Summable { @Override public int get...

Updating the state of a Swing component must happen on the Event Dispatch Thread (the EDT). The javax.swing.Timer triggers its ActionListener on the EDT, making it a good choice to perform Swing operations. The following example updates the text of a JLabel each two seconds: //Use a timer to updat...

public interface MyInterface { public void foo(); int bar(); public String TEXT = "Hello"; int ANSWER = 42; public class X { } class Y { } } Interface members always have public visibility, even if the public keyword is omitted. So both foo...

To create an IntentService, create a class which extends IntentService, and within it, a method which overrides onHandleIntent: package com.example.myapp; public class MyIntentService extends IntentService { @Override protected void onHandleIntent (Intent workIntent) { //Do so...

As you use generic types with utility classes, you may often find that number types aren't very helpful when specified as the object types, as they aren't equal to their primitive counterparts. List<Integer> ints = new ArrayList<Integer>(); Java SE 7 List<Integer> ints = new A...

Let's say you want to define an interface that allows publishing / consuming data to and from different types of channels (e.g. AMQP, JMS, etc), but you want to be able to switch out the implementation details ... Let's define a basic IO interface that can be re-used across multiple implementations...

Sometimes you may wish to read byte-input into a String. To do this you will need to find something that converts between byte and the "native Java" UTF-16 Codepoints used as char. That is done with a InputStreamReader. To speed the process up a bit, it's "usual" to allocate a b...

A primitive data type such as int holds values directly into the variable that is using it, meanwhile a variable that was declared using Integer holds a reference to the value. According to java API: "The Integer class wraps a value of the primitive type int in an object. An object of type Int...

By default, any files that you save to Internal Storage are private to your application. They cannot be accessed by other applications, nor the user under normal circumstances. These files are deleted when the user uninstalls the application. To Write Text to a File String fileName= "hellowor...

Since Java 6, the recommended way to access an SQL-based database in Java is via the JDBC(Java DataBase Connectivity) API. This API comes in two packagages: java.sql and javax.sql. JDBC defines database interactions in terms of Connections and Drivers. A Driver interacts with the database, and pr...

parse() from SimpleDateFormat class helps to convert a String pattern into a Date object. DateFormat dateFormat = DateFormat.getDateInstance(DateFormat.SHORT, Locale.US); String dateStr = "02/25/2016"; // input String Date date = dateFormat.parse(dateStr); System.out.println(date.getYe...

// Obtain an instance of JavaScript engine ScriptEngineManager manager = new ScriptEngineManager(); ScriptEngine engine = manager.getEngineByName("nashorn"); // Setup a custom writer StringWriter stringWriter = new StringWriter(); // Modify the engine context so that the custom writ...