Tutorial by Examples: ch

string helloWorld = "hello world, how is it going?"; string[] parts1 = helloWorld.Split(','); //parts1: ["hello world", " how is it going?"] string[] parts2 = helloWorld.Split(' '); //parts2: ["hello", "world,", "how", "is&qu...

String.Trim() string x = " Hello World! "; string y = x.Trim(); // "Hello World!" string q = "{(Hi!*"; string r = q.Trim( '(', '*', '{' ); // "Hi!" String.TrimStart() and String.TrimEnd() string q = "{(Hi*"; string r = q.TrimStart( '{...

The following is a bad idea because it would dispose the db variable before returning it. public IDBContext GetDBContext() { using (var db = new DBContext()) { return db; } } This can also create more subtle mistakes: public IEnumerable<Person> GetPeople(int age)...

Set function inserts a cache entry into the cache by using a CacheItem instance to supply the key and value for the cache entry. This function Overrides ObjectCache.Set(CacheItem, CacheItemPolicy) private static bool SetToCache() { string key = "Cache_Key"; string value = &quo...

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

Snippet public class BugReport : INotifyPropertyChanged { public string Title { ... } public BugStatus Status { ... } } ... private void BugReport_PropertyChanged(object sender, PropertyChangedEventArgs e) { var bugReport = (BugReport)sender; switch (e.PropertyName) ...

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(); } ...

Java SE 5 With Java 5 and up, one can use for-each loops, also known as enhanced for-loops: List strings = new ArrayList(); strings.add("This"); strings.add("is"); strings.add("a for-each loop"); for (String string : strings) { System.out.println(string); } For each ...

The String type provides two methods for converting strings between upper case and lower case: toUpperCase to convert all characters to upper case toLowerCase to convert all characters to lower case These methods both return the converted strings as new String instances: the original String o...

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...

The ScheduledExecutorService class provides a methods for scheduling single or repeated tasks in a number of ways. The following code sample assume that pool has been declared and initialized as follows: ScheduledExecutorService pool = Executors.newScheduledThreadPool(2); In addition to the nor...

String str = "My String"; System.out.println(str.charAt(0)); // "M" System.out.println(str.charAt(1)); // "y" System.out.println(str.charAt(2)); // " " System.out.println(str.charAt(str.length-1)); // Last character "g" To get the nth charac...

The switch statement is Java's multi-way branch statement. It is used to take the place of long if-else if-else chains, and make them more readable. However, unlike if statements, one may not use inequalities; each value must be concretely defined. There are three critical components to the switch...

Java's Reflection API allows the programmer to perform various checks and operations on class fields, methods and annotations during runtime. However, in order for an annotation to be at all visible at runtime, the RetentionPolicy must be changed to RUNTIME, as demonstrated in the example below: @i...

A char can store a single 16-bit Unicode character. A character literal is enclosed in single quotes char myChar = 'u'; char myChar2 = '5'; char myChar3 = 65; // myChar3 == 'A' It has a minimum value of \u0000 (0 in the decimal representation, also called the null character) and a maximum valu...

Parentheses are now forbidden around named parameters. The following compiles in C#5, but not C#6 5.0 Console.WriteLine((value: 23)); Operands of is and as are no longer allowed to be method groups. The following compiles in C#5, but not C#6 5.0 var result = "".Any is byte; T...

echo and print are language constructs, not functions. This means that they don't require parentheses around the argument like a function does (although one can always add parentheses around almost any PHP expression and thus echo("test") won't do any harm either). They output the string r...

A single case in a switch statement can match on multiple values. let number = 3 switch number { case 1, 2: print("One or Two!") case 3: print("Three!") case 4, 5, 6: print("Four, Five or Six!") default: print("Not One, Two, Three, Four, F...

A single case in a switch statement can match a range of values. let number = 20 switch number { case 0: print("Zero") case 1..<10: print("Between One and Ten") case 10..<20: print("Between Ten and Twenty") case 20..<30: print("Be...

Consider a database with the following two tables. Employees table: IdFNameLNameDeptId1JamesSmith32JohnJohnson4 Departments table: IdName1Sales2Marketing3Finance4IT Simple select statement * is the wildcard character used to select all available columns in a table. When used as a substitute f...