Java Source Code Examples

This page contains 1000+ Java source code examples. All the Java source code examples contain an output. You can use these Java source code examples and code snippets in your Java projects.

Here are the source code examples of important Java topics such as Java basics, String, Array, Collections, JDBC, Java 8 Lambda, Streams, Functional Interfaces, Date-time API, and more.

Latest Java Examples:

• Java Record Class Example
• Java Text Blocks Example
• Java Record Builder Pattern Example
• Java Record Constructor Example
• Java Record Constructor Validation Example
• Java Record Serializable Example
• Java Record Getter Example
• Java Record Default Constructor
• Java Records CRUD (Create, Read, Update, Delete) Example
• Java Record Custom Methods
• Java Record Custom toString
• Java Record Custom equals and hashCode
• Java Records with Spring Boot CRUD Example
• Java Record Implement Interface Example
• Java Switch Expressions Example
• Java Pattern Matching for instanceof
• Java Sealed Class Example
• Java Sealed Class vs Final Class
• Java Sealed Class Record Example
• Java Sealed Class Generic Example
• Java Sealed Class Enum Example
• Java Sealed Class Switch Example
• Java var Keyword Example
• Java CompactNumberFormat Class Example
• Java Vector API Example
• Pattern Matching for Switch Example
• Collectors.teeing() in Stream API Example
• Java FileSystems.newFileSystem() Method Example
• Java Files.readString() and Files.writeString() Example
• Java String isBlank Example
• Java String strip Example
• Java String repeat Example
• Java String lines Example
• Java String stripIndent Example

Java Basic Programs and Coding Examples

• Java Binary Search (Recursive and Iterative) Program
• Java Happy Birthday Program
• Java Program That Calculates the Age of a Person
• Java Logical And Or Xor Examples
• Java Format Date and Time Examples
• Java Convert String to Date and Time
• Java Convert Roman to Integer Number
• Java Convert Octal to HexaDecimal
• Java Convert Octal to Decimal
• Java Convert Integer Number to Roman Number
• Java Convert Hexadecimal to Binary
• Java Convert Decimal to Octal
• Java Convert Decimal to Binary
• Java Convert Binary to Decimal
• Java Convert Binary to an Octal
• Java Convert Binary to a Hexadecimal
• Java Convert a Unix Timestamp to Date Time
• Java Check If Two Integer Arrays are Equals
• Java program that removes all white spaces from the given string
• Java 8 program that counts the number of vowels and consonants in a given string
• Java 8 program that reverses words of a given string
• Java Program to Count Number of Digits in an Integer
• Java Program Fibonacci Series Using Recursion
• Java Program to Find Factorial of a Number
• Java program to calculate the area of Triangle
• Java Program to Calculate Area of Square
• Java Program to Calculate Area of Rectangle
• Java Program to find the Smallest of three numbers using Ternary Operator
• Java Program to Find Largest of Three Numbers
• Java Program to Find GCD of Two Numbers
• Java Program to Check Armstrong Number
• Java Program to Generate Random Number
• Java Program to Check if Number is Positive or Negative
• Java program to check prime number
• Java Program to Calculate Simple Interest
• Java Program to Swap Two Numbers Without using a Temporary Variable
• Java Program to Swap Two Numbers
• Java Program to Find ASCII Value of a Character
• Java Program to Check Whether an Alphabet is Vowel or Consonant
• Java Program to Check Leap Year
• Java Program to Check Even or Odd Number
• Java Program to Add Two Numbers
• Java Program to Swap Two Strings Without Using Third Variable
• Java Program to Swap Two Strings with Third Variable
• How to Get All Digits from String in Java
• Find Duplicate Number in Array in Java
• How to Get Current Working Directory in Java?
• Check Palindrome String in Java
• Java Program to Create Pyramid Of Numbers

Java String Source Code Examples

• Create a String object in Java Example
• Java String valueOf() Method Example
• Java String.trim() Method Example
• Java String.toUpperCase() Method Example
• Java String toLowerCase() Method Example
• Java String toCharArray() Method Example
• Java String substring() Method Example
• Java String.startsWith() Method Example
• Java String split() Method Example
• Java String.replaceFirst() Method Example
• Java String.replaceAll() Method Example
• Java String replace() Method Example
• Java String regionMatches() Method Example
• Java String length() Method Example
• Java String lastIndexOf() Method Example
• Java String intern() Method Example
• Java String indexOf() Method Example
• Java String getChars() Method Example
• Java String getBytes() Method Example
• Java String equals() and equalsIgnoreCase() Example
• Java String.endsWith() Method Example
• Java String.contentEquals() Method Example
• Java String.contains() Method Example
• Java String concat() Method Example
• What's the Simplest Way to Print a Java Array?
• Merge two String Arrays Example
• Checks If a String is Not Empty and Not Null in Java
• Reverse a String in Java Using StringBuilder
• Capitalize the First Letter of a String in Java Example
• Java String codePointAt() Method Example
• Java String Compare Using equals() Method
• Sort String in Descending Order in Java
• Sort String in Ascending Order in Java

Java String Utility Methods Code Examples

• How to Get All Digits from String in Java
• Java String getDigits() Utility Method
• Java String isAlphanumeric() Utility Method
• Java String isAlpha() Utility Method
• Java String countMatches() Utility Method
• Java String mergeStringArrays(String array1[], String array2[]) Utility Method Example
• Java String quote( String str) Utility Method
• Java arrayToMap(String[][] array) Utility Method
• Java String fromBufferedReader() Utility Method - Converts a BufferedReader into a String
• Java String isNumericSpace() Utility Method
• Java String isNumeric() Utility Method
• Java String isAlphanumericSpace() Utility Method
• Java String isAlphaSpace(() Utility Method
• Java trimArrayElements() Utility Method
• Java trimArrayElements() Utility Method
• Java String containsWhitespace() Utility Method
• Java String isBlank() Utility Method
• Java String isAnyEmpty() Utility Method
• Java String isNotEmpty() Utility Method
• Java String isEmpty() Utility Method
• Java String Uppercase First Character Example
• Java String uppercaseFirstChar() Utility Method
• Java String trimTrailingCharacter() Utility Method
• Java String trimLeadingCharacter() Utility Method
• Java String trimTrailingWhitespace() Utility Method
• Java String trimLeadingWhitespace() Utility Method
• Java String trimAllWhitespace() Utility Method
• Java String trimWhitespace() Utility Method

Java StringBuilder Source Code Examples

• Java StringBuilder trimToSize() Method Example
• Java StringBuilder substring() Method Example
• Java StringBuilder setLength() Method Example
• Java StringBuilder reverse() Method Example
• Java StringBuilder lastIndexOf() Method Example
• Java StringBuilder insert() Method Example
• Java StringBuilder indexOf() Method Example
• Java StringBuilder getChars() Method Example
• Java StringBuilder ensureCapacity() Method Example
• Java StringBuilder deleteCharAt() Method Example
• Java StringBuilder delete() Method Example
• Java StringBuilder codePointBefore() Method Example
• Java StringBuilder codePointAt Method Example
• Java StringBuilder capacity() Method Example
• Java StringBuilder append() Method Example

Java String Conversion Code Examples

Conversion from String to Wrapper classes or Primitive types:

• Java Convert Integer to String Example
• Java Convert Float to String Example
• Java Convert Double to String Example
• Java Convert Short to String Example
• Java Convert Long to String Example
• Java Convert Character to String Example
• Java Convert Byte to String Example
• Java Convert Boolean to String Example

Conversion from Wrapper classes or Primitive types to String:

• Java Convert String To Short Example
• Java Convert String To Long Example
• Java Convert String To Integer Example
• Java Convert String To Float Example
• Java Convert String To Double Example
• Java Convert String To Byte Example
• Java Convert String To Boolean Example

Java ArrayList Source Code Examples

• Clear ArrayList in Java Example
• Java ArrayList add(), get() and set() Method Example
• Iterate over ArrayList Using forEach Java
• Iterate over ArrayList using Iterator in Java
• Java ArrayList indexOf() and lastIndexOf() Example
• Search an Element in an ArrayList in Java
• Java ArrayList removeAll() Method Example
• Java ArrayList remove() Method Example
• How to Iterate over ArrayList in Java
• How to Remove Element from ArrayList in Java
• How to Access Elements of ArrayList in Java
• Create ArrayList from Another ArrayList in Java
• How to Create an ArrayList and Add Elements to It
• Java ArrayList subList() Example
• Get Index of Elements in ArrayList Example
• Java ArrayList removeIf() Example

Java Arrays Source Code Examples

• Copying part of Array in Java Example
• Sorting an Array using Arrays.sort() Method
• Check Two Arrays are Deeply Equal
• Java Arrays.copyOf() Example - Copying an Array
• Java Arrays.binarySearch() Example - Searching an Array
• Java Arrays.asList() Example - Convert Array to ArrayList

Java Collections Utility Class Code Examples

• Sort String in Ascending Order in Java
• Sort String in Descending Order in Java
• Sort Integer in Ascending Order in Java Example
• Sort Integer in Descending Order in Java Example
• Sort User-Defined Objects in Ascending Order in Java
• Sort User-Defined Objects in Descending Order in Java
• Sort User-Defined Objects using Comparator Interface

Java LinkedList Source Code Examples

• Java LinkedList add(), addFirst(), addLast() and addAll() Example
• Iterate LinkedList using forEach() Method Example
• Iterate through a LinkedList using an Iterator in Java
• Iterate or Loop Through Elements LinkedList in Java Example
• Search Elements of LinkedList in Java with Example
• Remove First and Last Elements of LinkedList in Java
• Get Elements from LinkedList Java Example
• Java LinkedList remove(), removeFirst(), removeLast(), removeIf() and clear() Example

Java HashSet Source Code Examples

• Create HashSet in Java
• Iterating over a HashSet using Iterator
• Iterate over HashSet in Java
• Remove Element from HashSet in Java
• Create HashSet in Java

Java LinkedHashSet Source Code Examples

• Iterating over a LinkedHashSet using forEach() Method Example
• Iterate over LinkedHashSet using Iterator in Java Example
• Iterate over LinkedHashSet in Java Example
• Remove all Elements from LinkedHashSet in Java Example
• Remove Element from LinkedHashSet Example
• Check If an Element Exists in Java LinkedHashSet Example
• Create LinkedHashSet in Java Example

Java TreeSet Source Code Examples

• Create TreeSet in Java Example
• Iterating over a TreeSet using Java 8 forEach() Method
• Iterate over a TreeSet using Iterator in Java Example
• Iterate over TreeSet in Java Example
• Remove All Elements from Java TreeSet Example
• Remove First and Last Element from TreeSet in Java
• Remove Element from TreeSet in Java Example
• Check If an Element Exists in Java TreeSet Example
• Java TreeSet add(), first() and last() Method Example

Java Stack Source Code Examples

• Java Convert ArrayList to Stack Example
• Java Convert Array to Stack Example
• Java Stack push() Method Example
• Java Stack empty() Method Example
• Java Stack peek() Method Example
• Java Stack search() Method Example
• Java Stack pop() Method Example

Java Queue Source Code Examples

• Java Deque and ArrayDeque Examples
• Iterating over a Queue in Java Example
• Java Queue isEmpty(), size(), element() and peek() Example
• Java Queue Interface Example
• Java Priority Queue of User Defined Objects Example
• Java Create a Priority Queue with a Custom Comparator
• Create a Priority Queue in Java Example

Java HashMap Source Code Examples

• HashMap Stream and Filtering Example
• Java HashMap Iteration over Values Example
• Java HashMap Iteration over Keys
• Java HashMap replace() Example
• Java HashMap size Example
• Iterate over a HashMap Java using Lambda
• Iterate over a HashMap Java 8 forEach
• Iterating over a HashMap using Iterator in Java
• Iterate over HashMap in Java
• How to Store Employee Objects in HashMap
• Remove Entry from HashMap Java
• Check If Value Exists in HashMap Java Example
• Check If Key Exists in HashMap Java Example
• Create a HashMap in Java Example

Java JDBC Source Code Examples

• How to Delete Data from MySQL Table using Java
• How to Insert Data in MySQL Table using Java
• How to Create Database Table in Java
• JDBC DriverManager Example
• JDBC PreparedStatement Example
• JDBC Statement Example
• Java MySQL DataSource Example
• Update Query in MySQL using Java PreparedStatement
• Login Example with JSP + Servlet + JDBC + MySQL Database
• JSP + JDBC + MySQL Example Tutorial
• JSP Form Example with JDBC and MySQL Database
• Java JDBC CRUD Example - SQL Insert, Select, Update, and Delete Examples
• Java Swing JDBC MySQL Database Example
• Java JDBC Connection to HSQLDB Database
• JDBC Connection to H2 Database Example
• JDBC Connection to PostgreSQL Example
• JDBC Connection to Oracle Database Example
• JDBC Transaction Management Example
• JDBC Delete Query Example
• JDBC Select Query Example
• JDBC Update Query Example
• JDBC Insert Multiple Rows Example
• JDBC Create a Table Example
• What are different types of JDBC Drivers
• Advantages of Hibernate Framework over JDBC
• Java PostgreSQL Example
• Java H2 Insert Record Example
• Java H2 Embedded Database Example
• Java H2 Create Table Example

Java 8 Lambda Source Code Examples

• Java Simple Lambda Expression Example
• Java Lambda Expressions Multiple Statements
• Java Lambda Expressions forEach Example
• Java Lambda Expression with Multiple Parameters Example
• Java Lambda Expression Runnable Example
• Java Lambda Expression Comparator Example
• Refactoring Factory Design Pattern with Lambdas
• Refactoring Chain of Responsibility Pattern with Lambdas
• Refactoring Observer Design Pattern with Lambdas
• Refactoring Strategy Design Pattern with Lambdas
• Iterate HashMap with forEach() + Lambda Expression Example
• Iterate HashSet with forEach() + Lambda Expression Example
• Iterate ArrayList with forEach() + Lambda Expression Example

Java Method References Source Code Examples

• Java method reference to a constructor example
• Java method reference to static method example
• Java method reference to an instance method of an object example
• Java method reference to an instance method of an arbitrary object of a particular type

Java 8 Stream API Source Code Examples

• Java 8 - Create Stream Object from Arrays Example
• Java 8 Creating a Stream from an Array
• Java 8 - Create Stream Object from Collection, List, Set
• Java 8 Stream - Sort List of String objects in Descending Order Example
• Java 8 Stream - Sort List of String objects in Ascending Order Example
• How to convert a Java 8 Stream to an Array?
• Java 8 Stream - allMatch(),anyMatch() and noneMatch() Example
• Java 8 Stream - Sort List of Objects by Multiple Fields
• Java 8 Stream - Sort List of Custom Objects in Ascending and Descending Order
• Java 8 - Stream filter(), forEach(), collect() and Collectors.toList() Example
• Java Stream filter null values example
• Java Stream filter map by values example
• Java Stream filter map by keys example
• Java 8 Collectors.counting() Example
• Java 8 Collectors.averagingDouble() Example
• Java 8 Collectors.toSet() Example
• Java 8 Collectors.toList() Example
• Java 8 Collectors.joining() example
• Java 8 Stream multiple filter operations
• Java 8 Stream filter map by keys
• Java 8 Stream filter map by values
• Java 8 Stream collect to list example
• Java 8 Stream Collectors.counting() exmaple
• Java 8 Collectors.collectingAndThen() example
• Java 8 Collectors.toList() Example
• Java 8 Collectors.minBy() and Collectors.maxBy() example

Java Stream Methods/APIs Examples

• Java Stream filter() Example
• Java Stream map() Example
• Java Stream flatMap() Example
• Java Stream distinct() Example
• Java Stream limit() Example
• Java Stream peek() Example
• Java Stream anyMatch() Example
• Java Stream allMatch() Example
• Java Stream noneMatch() Example
• Java Stream collect() Example
• Java Stream count() Example
• Java Stream findAny() Example
• Java Stream findFirst() Example
• Java Stream forEach() Example
• Java Stream min() Example
• Java Stream max() Example
• Java Stream reduce() Example
• Java Stream toArray() Example

Java 8 Functional Interface Source Code Examples

• Java Function Functional Interface Example
• Java Supplier Functional Interface Example
• Java Consumer Example
• Java BiConsumer Example
• Java BiFunction Example
• Java Predicate Example
• Java 8 LongConsumer Example
• Java 8 IntConsumer Example
• Java 8 DoubleConsumer Example
• Java StringJoiner Example

Optional Class Source Code Examples

• Create Optional Class Object in Java - empty(), of(), ofNullable() Methods
• Optional get() Method - Get Value from Optional Object in Java
• Optional isPresent() Method Example
• Optional orElse() Method Example
• Optional orElseGet() Method Example
• Optional orElseThrow() Method Example
• Optional filter() and map() Method Examples

Java 8 - Misc

• Java 8 program that counts the number of vowels and consonants in a given string
• Java 8 program that reverses words of a given string
• Java 8 - Copy List into Another List Example
• Check Whether the Given Year is Leap Year or Not in Java
• Java 8 forEach() Array Example
• Java 8 forEach() Map Example
• Java 8 forEach() Set Example
• Java 8 forEach() List Example

Java 8 Date-Time API Source Code Examples

• Getting current date and time with Clock
• Convert LocalDate to Date in Java
• Convert LocalDateTime into Date in Java
• Connvert java.util.Date to java.time.LocalDateTime Example
• Convert java.util.Date to java.time.LocalDate Example
• Duration Between Two LocalDate in Java
• Java Convert ZonedDateTime to String Example
• Convert String to ZonedDateTime in Java
• Compare ZonedDateTime Objects in Java
• How to Get Hour, Minute, Second from ZonedDateTime in Java
• Convert ZonedDateTime to LocalTime Example
• Convert ZonedDateTime to LocalDateTime in Java
• Java ZonedDateTime now() and of() Method Example
• Convert LocalDateTime to LocalTime in Java
• Convert LocalDateTime to LocalDate in Java
• Compare LocalDateTime Objects in Java
• Java LocalDateTime - Get Hour, Minute and Second
• How to Get Day Month and Year from LocalDateTime in Java
• Java LocalDateTime now() Method Example
• How to Get Current Date Time in Java
• Convert LocalDate to String in Java
• Convert String to LocalDate in Java
• Java LocalDate isLeapYear() Method Example
• How to Get Number of Days from Month and Year using LocalDate in Java
• Compare Java LocalDate Objects Example
• How to Add Days Weeks Months and Years to LocalDate in Java
• How to get Day Month and Year from LocalDate in Java
• Java LocalDate now() Method Example - Get Current Date and Specific Date
• Convert LocalTime to String in Java
• Convert String to LocalTime in Java
• Java LocalTime isBefore() and isAfter() Method Example
• How to Compare Time in Java
• Java 8 - LocalTime getHour(), getMinute(), getSecond() and getNano() Example
• Java LocalTime now() Method Example - Get Current Time and Specific Time
• Java 8 Get Local Date Time in All Available Time Zones
• How to get year, month, day, hours, minutes, seconds and milliseconds of LocalDateTime in Java 8?
• How to get year, month, day, hours, minutes, seconds and milliseconds of Date in Java?
• Difference between Two Dates in Java
• Create LocalDateTime from LocalDate and LocalTime in Java