Java Language
- Getting started with Java Language
- Top 10 Java Errors with Solutions
- Awesome Book
- Awesome Community
- Awesome Course
- Awesome Tutorial
- Awesome YouTube
- 2D Graphics in Java
- Alternative Collections
- Annotations
- Apache Commons Lang
- AppDynamics and TIBCO BusinessWorks Instrumentation for Easy Integration
- Applets
- Arrays
- Asserting
- Atomic Types
- Audio
- Autoboxing
- Basic Control Structures
- Benchmarks
- BigDecimal
- BigInteger
- Bit Manipulation
- BufferedWriter
- ByteBuffer
- Bytecode Modification
- C++ Comparison
- Calendar and its Subclasses
- Character encoding
- Choosing Collections
- Class - Java Reflection
- Classes and Objects
- Classloaders
- Collection Factory Methods
- Collections
- Command line Argument Processing
- Common Java Pitfalls
- Comparable and Comparator
- CompletableFuture
- Concurrent Collections
- Concurrent Programming (Threads)
- Console I/O
- Constructors
- Converting to and from Strings
- Creating Images Programmatically
- Currency and Money
- Date Class
- Dates and Time (java.time.*)
- Default Methods
- Dequeue Interface
- Disassembling and Decompiling
- Documenting Java Code
- Dynamic Method Dispatch
- Encapsulation
- Enum Map
- Enum starting with number
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- EnumSet class
- Exceptions and exception handling
- Executor, ExecutorService and Thread pools
- Expressions
- File I/O
- FileUpload to AWS
- Fluent Interface
- FTP (File Transfer Protocol)
- Functional Interfaces
- Generating Java Code
- Generics
- Getters and Setters
- Hashtable
- HttpURLConnection
- Immutable Class
- Immutable Objects
- Inheritance
- InputStreams and OutputStreams
- Installing Java (Standard Edition)
- Interfaces
- Iterator and Iterable
- Java Agents
- Java Compiler - 'javac'
- Java deployment
- Java Editions, Versions, Releases and Distributions
- Java Floating Point Operations
- Java Memory Management
- Java Memory Model
- Java Native Access
- Java Native Interface
- Java Performance Tuning
- Java Pitfalls - Exception usage
- Java Pitfalls - Language syntax
- Java Pitfalls - Nulls and NullPointerException
- Java Pitfalls - Performance Issues
- Pitfall - Calling 'new String(String)' is inefficient
- Pitfall - Calling System.gc() is inefficient
- Pitfall - Efficiency concerns with regular expressions
- Pitfall - Interning strings so that you can use == is a bad idea
- Pitfall - Iterating a Map's keys can be inefficient
- Pitfall - Over-use of primitive wrapper types is inefficient
- Pitfall - Small reads / writes on unbuffered streams are inefficient
- Pitfall - String concatenation in a loop does not scale
- Pitfall - The overheads of creating log messages
- Pitfall - Using 'new' to create primitive wrapper instances is inefficient
- Pitfall - Using size() to test if a collection is empty is inefficient.
- Java Pitfalls - Threads and Concurrency
- Java plugin system implementations
- Java Print Service
- Java SE 7 Features
- Java SE 8 Features
- Java Sockets
- Java Virtual Machine (JVM)
- JavaBean
- JAXB
- JAX-WS
- JMX
- JNDI
- JShell
- JSON in Java
- Just in Time (JIT) compiler
- JVM Flags
- JVM Tool Interface
- Lambda Expressions
- LinkedHashMap
- List vs SET
- Lists
- Literals
- Local Inner Class
- Localization and Internationalization
- LocalTime
- log4j / log4j2
- Logging (java.util.logging)
- Maps
- Modules
- Multi-Release JAR Files
- Nashorn JavaScript engine
- Nested and Inner Classes
- Networking
- New File I/O
- NIO - Networking
- Non-Access Modifiers
- NumberFormat
- Object Class Methods and Constructor
- Object Cloning
- Object References
- Operators
- Optional
- Oracle Official Code Standard
- Packages
- Parallel programming with Fork/Join framework
- Polymorphism
- Preferences
- Primitive Data Types
- Process
- Properties Class
- Queues and Deques
- Random Number Generation
- Readers and Writers
- Recursion
- Reference Data Types
- Reference Types
- Reflection API
- Regular Expressions
- Remote Method Invocation (RMI)
- Resources (on classpath)
- RSA Encryption
- Runtime Commands
- Scanner
- Secure objects
- Security & Cryptography
- Security & Cryptography
- SecurityManager
- Serialization
- ServiceLoader
- Sets
- Singletons
- Sockets
- SortedMap
- Splitting a string into fixed length parts
- Stack-Walking API
- Streams
- String Tokenizer
- StringBuffer
- StringBuilder
- Strings
- sun.misc.Unsafe
- super keyword
- The Classpath
- The Java Command - 'java' and 'javaw'
- The java.util.Objects Class
- ThreadLocal
- TreeMap and TreeSet
- Type Conversion
- Unit Testing
- Using Other Scripting Languages in Java
- Using the static keyword
- Using ThreadPoolExecutor in MultiThreaded applications.
- Varargs (Variable Argument)
- Visibility (controlling access to members of a class)
- WeakHashMap
- XJC
- XML Parsing using the JAXP APIs
- XML XPath Evaluation
- XOM - XML Object Model
Java Language Java Pitfalls - Performance Issues Pitfall - Calling 'new String(String)' is inefficient
Example
Using new String(String) to duplicate a string is inefficient and almost always unnecessary.
- String objects are immutable, so there is no need to copy them to protect against changes.
- In some older versions of Java,
Stringobjects can share backing arrays with otherStringobjects. In those versions, it is possible to leak memory by creating a (small) substring of a (large) string and retaining it. However, from Java 7 onwards,Stringbacking arrays are not shared.
In the absence of any tangible benefit, calling new String(String) is simply wasteful:
- Making the copy takes CPU time.
- The copy uses more memory which increases the application's memoru footprint and / or increases GC overheads.
- Operations like
equals(Object)andhashCode()can be slower if String objects are copied.
