Tutorial by Examples: le

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...

Create a property with getter and/or setter and initialize all in one line: public string Foobar { get; set; } = "xyz";

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...

Sorting lists Prior to Java 8, it was necessary to implement the java.util.Comparator interface with an anonymous (or named) class when sorting a list1: Java SE 1.2 List<Person> people = ... Collections.sort( people, new Comparator<Person>() { public int compare(Pe...

This is an example of a default build.gradle file in a module. apply plugin: 'com.android.application' android { compileSdkVersion 25 buildToolsVersion '25.0.3' signingConfigs { applicationName { keyAlias 'applicationName' keyPassword 'password...

public class SampleAdapter extends RecyclerView.Adapter<SampleAdapter.ViewHolder> { private String[] mDataSet; private OnRVItemClickListener mListener; /** * Provide a reference to the type of views that you are using (custom ViewHolder) */ public static cla...

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 { ...

Addition Map<Integer, String> map = new HashMap<>(); map.put(1, "First element."); System.out.println(map.get(1)); Output: First element. Override Map<Integer, String> map = new HashMap<>(); map.put(1, "First element."); map.put(1, &quot...

We can use V put(K key,V value): Associates the specified value with the specified key in this map (optional operation). If the map previously contained a mapping for the key, the old value is replaced by the specified value. String currentVal; Map<Integer, String> map = new TreeMap&l...

Map<Integer, String> map = new HashMap<>(); map.put(1, "First element."); map.put(2, "Second element."); map.put(3, "Third element."); map.clear(); System.out.println(map.size()); // => 0

Consider the following JSON string: { "title": "test", "content": "Hello World!!!", "year": 2016, "names" : [ "Hannah", "David", "Steve" ] } This JSON object can...

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...

First example reimplemented in Kotlin and using RxJava for cleaner interaction. import android.view.LayoutInflater import android.view.View import android.view.ViewGroup import android.support.v7.widget.RecyclerView import rx.subjects.PublishSubject public class SampleAdapter(private val ite...

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"); ...

class TrivialClass {} A class consists at a minimum of the class keyword, a name, and a body, which might be empty. You instantiate a class with the new operator. TrivialClass tc = new TrivialClass();

int i = 0; while (i < 100) { // condition gets checked BEFORE the loop body executes System.out.println(i); i++; } A while loop runs as long as the condition inside the parentheses is true. This is also called the "pre-test loop" structure because the conditional stateme...

The do...while loop differs from other loops in that it is guaranteed to execute at least once. It is also called the "post-test loop" structure because the conditional statement is performed after the main loop body. int i = 0; do { i++; System.out.println(i); } while (i &l...

Using BufferedReader: System.out.println("Please type your name and press Enter."); BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); try { String name = reader.readLine(); System.out.println("Hello, " + name + "!"); } catch(I...

For basic prototypes or basic command-line behavior, the following loop comes in handy. public class ExampleCli { private static final String CLI_LINE = "example-cli>"; //console like string private static final String CMD_QUIT = "quit"; //string for exit...