Java Pages

Dot Net Perls has example pages for many languages, with explanations and code side by side (for easy understanding).
ArrayList. Build up a collection of many strings or integers with the ArrayList class from java.util.ArrayList.Java ArrayList Examples
Lambdas. Invoke lambda expressions, creating instances of Functions, Suppliers and Consumers.Java Lambda Expressions
2D array. Use 2D arrays and jagged arrays. Initialize arrays and assign elements.Java 2D Array Examples
Array. Use arrays: create and initialize string and int arrays. Use for to iterate over arrays.Java Array Examples
Boolean. Use the boolean type and the values true and false. Test them with expressions and ifs.Java Boolean Examples: If True, False
Casts. Cast variables, including objects and numbers. Arrays too are cast.Java Cast and Convert Types
Character. Use the Character class to test and transform chars. Call isLetter, isDigit and toLowerCase.Java Character: isLetter, isDigit and toLowerCase
Console. Use the System.out println and print methods. Read console input with Console Examples: System.out and
Files. Handle files with BufferedReader and FileReader. Use readLine on text files.Java File: BufferedReader and FileReader
For. Use the for-loop to iterate over numeric ranges and collections. Compare different loops.Java For Loop Examples
Format. Use String.format to create strings with variables inserted in them. Handle integers and strings.Java String.format Examples: Numbers and Strings
HashMap. Use the HashMap class from java.util.HashMap. Perform fast key lookups with hashing.Java HashMap Examples
HashSet. Use the HashSet type as a set collection. Test for element existence and uniqueness.Java HashSet Examples
If. Use the if-statement to test a variable. Apply the if-statement, else-if and else.Java if, else if, else Statements
IndexOf. Use indexOf to search for characters and strings. Call indexOf in while-loops.Java indexOf Examples
Integer, maximum. Examine the MIN_VALUE and MAX_VALUE final ints on Integer and other classes. Use loop boundaries.Java Integer.MAX VALUE, MIN and SIZE
Keywords. Learn about keywords in the Java language. Review core parts of Java.Java Keywords
Math. Use the Math class, part of java.lang.Math. Call Math.floor, ceil and other methods.Java Math Class: java.lang.Math
ParseInt. Use parseInt to convert strings into ints. Test for valid strings and handle NumberFormatException.Java parseInt: Convert String to Int
Process. Use ProcessBuilder and Process.start. Issue operating system commands with start.Java Process.start EXE: ProcessBuilder Examples
Random. Use the Random class and the Math.random method. Generate random numbers.Java Random Number Examples
Regex. Use Regex: create Pattern and Matcher. Text is tested with regular expressions.Java Regex Examples (Pattern.matches)
Remove duplicates. Remove duplicates from an ArrayList of strings. Use a HashSet in removeDuplicates.Java Remove Duplicates From ArrayList
Replace. Use replace, replaceFirst and replaceAll to swap strings, chars and CharSequences.Java Replace Strings: replaceFirst and replaceAll
Return. Use the return keyword in methods. Return multiple values, return expressions and fix errors.Java Return Examples: Expressions and Void
Sort. Sort elements in arrays and other collections. Use Arrays.sort and the Comparable interface.Java Sort Examples: Arrays.sort, Comparable
Split. Separate strings on a delimiter with the split method. Split lines of a file.Java Split Examples
Stream. Explore the Stream class. Call and convert an ArrayList to a Stream.Java Stream: and ArrayList stream
String. Review the String class. Declare, concatenate and manipulate strings.Java String Class
StringBuilder. Use the StringBuilder class to append Strings. Benchmark and test StringBuilder.Java StringBuilder Examples
Substring. Use the substring and subSequence methods. One or two indexes can be specified.Java Substring Examples, subSequence
Switch. Use switch, and the case, default and break statements, to run code based on a variable.Java Switch Examples: Case and Break
Vector. Use the Vector type, from java.util.Vector. Vector is a resizable, thread-safe array.Java Vector Examples
While. Loop with while: this loop helps when proceeding until an unknown end condition is reached.Java While Loop Examples
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