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The nameof operator allows you to get the name of a variable, type or member in string form without hard-coding it as a literal. The operation is evaluated at compile-time, which means that you can rename, using an IDE's rename feature, a referenced identifier and the name string will update with it...

Snippet public void DoSomething(int paramValue) { Console.WriteLine(nameof(paramValue)); } ... int myValue = 10; DoSomething(myValue); Console Output paramValue

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...

An exception can be caught and handled using the try...catch statement. (In fact try statements take other forms, as described in other examples about try...catch...finally and try-with-resources.) Try-catch with one catch block The most simple form looks like this: try { doSomething(); } ...

We can create an ArrayList (following the List interface): List aListOfFruits = new ArrayList(); Java SE 5 List<String> aListOfFruits = new ArrayList<String>(); Java SE 7 List<String> aListOfFruits = new ArrayList<>(); Now, use the method add to add a String: ...

Generics enable classes, interfaces, and methods to take other classes and interfaces as type parameters. This example uses generic class Param to take a single type parameter T, delimited by angle brackets (<>): public class Param<T> { private T value; public T getValue() ...

To use a NavigationView just add the dependency in the build.gradle file as described in the remarks section Then add the NavigationView in the layout <?xml version="1.0" encoding="utf-8"?> <android.support.v4.widget.DrawerLayout xmlns:android="http://schema...

The following example shows the basics of throwing an exception: public void checkNumber(int number) throws IllegalArgumentException { if (number < 0) { throw new IllegalArgumentException("Number must be positive: " + number); } } The exception is thrown on the 3...

Basic cases int[] numbers1 = new int[3]; // Array for 3 int values, default value is 0 int[] numbers2 = { 1, 2, 3 }; // Array literal of 3 int values int[] numbers3 = new int[] { 1, 2, 3 }; // Array of 3 int values initialized int[][] numbers4 = { { 1, 2...

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...

Create the JSONObject using the empty constructor and add fields using the put() method, which is overloaded so that it can be used with different types: try { // Create a new instance of a JSONObject final JSONObject object = new JSONObject(); // With put you can add a name/va...

Two methods in java.util.Collection create an array from a collection: Object[] toArray() <T> T[] toArray(T[] a) Object[] toArray() can be used as follows: Java SE 5 Set<String> set = new HashSet<String>(); set.add("red"); set.add("blue"); ...

Methods can also have generic type parameters. public class Example { // The type parameter T is scoped to the method // and is independent of type parameters of other methods. public <T> List<T> makeList(T t1, T t2) { List<T> result = new ArrayList<T&...

Java 7 introduced the very useful Files class Java SE 7 import java.nio.file.Files; import java.nio.file.Paths; import java.nio.file.Path; Path path = Paths.get("path/to/file"); try { byte[] data = Files.readAllBytes(path); } catch(IOException e) { e.printStackTrace();...

In order to define a string array write in a resources file res/values/filename.xml <string-array name="string_array_name"> <item>text_string</item> <item>@string/string_id</item> </string-array> for example res/values/arrays.xml <?x...

A Toolbar is a generalization of ActionBar for use within application layouts. While an ActionBar is traditionally part of an Activity's opaque window decor controlled by the framework, a Toolbar may be placed at any arbitrary level of nesting within a view hierarchy. It can be added by performing t...

The Arrays.asList() method can be used to return a fixed-size List containing the elements of the given array. The resulting List will be of the same parameter type as the base type of the array. String[] stringArray = {"foo", "bar", "baz"}; List<String> stringL...

In the ActionListener attached to a javax.swing.Timer, you can keep track of the number of times the Timer executed the ActionListener. Once the required number of times is reached, you can use the Timer#stop() method to stop the Timer. Timer timer = new Timer( delay, new ActionListener() { priv...

To check whether a particular String a is being contained in a String b or not, we can use the method String.contains() with the following syntax: b.contains(a); // Return true if a is contained in b, false otherwise The String.contains() method can be used to verify if a CharSequence can be fou...

By using startActivityForResult(Intent intent, int requestCode) you can start another Activity and then receive a result from that Activity in the onActivityResult(int requestCode, int resultCode, Intent data) method. The result will be returned as an Intent. An intent can contain data via a Bundle ...