Tutorial by Examples: is

Snippet public class Person : INotifyPropertyChanged { private string _address; public event PropertyChangedEventHandler PropertyChanged; private void OnPropertyChanged(string propertyName) { PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName))...

Say we have a button (we can create it programmatically, or bind it from a view using findViewbyId(), etc...) Button btnOK = (...) Now, create an anonymous class and set it inline. btnOk.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { ...

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: ...

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...

Visible to the class, package, and subclass. Let's see an example with the class Test. public class Test{ public int number = 2; public Test(){ } } Now let's try to create an instance of the class. In this example, we can access number because it is public. public class Ot...

private visibility allows a variable to only be accessed by its class. They are often used in conjunction with public getters and setters. class SomeClass { private int variable; public int getVariable() { return variable; } public void setVariable(int variable) { ...

With no modifier, the default is package visibility. From the Java Documentation, "[package visibility] indicates whether classes in the same package as the class (regardless of their parentage) have access to the member." In this example from javax.swing, package javax.swing; public abs...

Protected visibility causes means that this member is visible to its package, along with any of its subclasses. As an example: package com.stackexchange.docs; public class MyClass{ protected int variable; //This is the variable that we are trying to access public MyClass(){ var...

Buttons fire action events when they are activated (e.g. clicked, a keybinding for the button is pressed, ...). button.setOnAction(new EventHandler<ActionEvent>() { @Override public void handle(ActionEvent event) { System.out.println("Hello World!"); } }); ...

Don't just use Optional.get() since that may throw NoSuchElementException. The Optional.orElse(T) and Optional.orElseGet(Supplier<? extends T>) methods provide a way to supply a default value in case the Optional is empty. String value = "something"; return Optional.ofNullable(v...

Use the orElseThrow() method of Optional to get the contained value or throw an exception, if it hasn't been set. This is similar to calling get(), except that it allows for arbitrary exception types. The method takes a supplier that must return the exception to be thrown. In the first example, the...

The Collections class offers two standard static methods to sort a list: sort(List<T> list) applicable to lists where T extends Comparable<? super T>, and sort(List<T> list, Comparator<? super T> c) applicable to lists of any type. Applying the former requires amending...

WebHistory history = webView.getEngine().getHistory(); The history is basically a list of entries. Each entry represents a visited page and it provides access to relevant page info, such as URL, title, and the date the page was last visited. The list can be obtained by using the getEntries() met...

BindingList<string> listOfUIItems = new BindingList<string>(); listOfUIItems.Add("Alice"); listOfUIItems.Add("Bob");

Optional<String> optionalWithValue = Optional.of("foo"); optionalWithValue.ifPresent(System.out::println);//Prints "foo". Optional<String> emptyOptional = Optional.empty(); emptyOptional.ifPresent(System.out::println);//Does nothing.

A list comprehension creates a new list by applying an expression to each element of an iterable. The most basic form is: [ <expression> for <element> in <iterable> ] There's also an optional 'if' condition: [ <expression> for <element> in <iterable> if <c...

The division operator (/) perform arithmetic division on numbers (literals or variables). console.log(15 / 3); // 5 console.log(15 / 4); // 3.75

Given a list comprehension you can append one or more if conditions to filter values. [<expression> for <element> in <iterable> if <condition>] For each <element> in <iterable>; if <condition> evaluates to True, add <expression> (usually a function...

Python lists are zero-indexed, and act like arrays in other languages. lst = [1, 2, 3, 4] lst[0] # 1 lst[1] # 2 Attempting to access an index outside the bounds of the list will raise an IndexError. lst[4] # IndexError: list index out of range Negative indices are interpreted as countin...

To iterate through a list you can use for: for x in ['one', 'two', 'three', 'four']: print(x) This will print out the elements of the list: one two three four The range function generates numbers which are also often used in a for loop. for x in range(1, 6): print(x) The res...