assignment to itself java

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Java Assignment Operators

Description.

Assigning a value to a variable seems straightforward enough; you simply assign the stuff on the right side of the '= 'to the variable on the left. Below statement 1 assigning value 10 to variable x and statement 2 is creating String object called name and assigning value "Amit" to it.

Assignment can be of various types. Let’s discuss each in detail.

Primitive Assignment:

The equal (=) sign is used for assigning a value to a variable. We can assign a primitive variable using a literal or the result of an expression.

Primitive Casting

Casting lets you convert primitive values from one type to another. We need to provide casting when we are trying to assign higher precision primitive to lower precision primitive for example If we try to assign int variable (which is in the range of byte variable) to byte variable then the compiler will throw an exception called "possible loss of precision". Eclipse IDE will suggest the solution as well as shown below. To avoid such problem we should use type casting which will instruct compiler for type conversion.

For cases where we try to assign smaller container variable to larger container variables we do not need of explicit casting. The compiler will take care of those type conversions. For example, we can assign byte variable or short variable to an int without any explicit casting.

Assigning Literal that is too large for a variable

When we try to assign a variable value which is too large (or out of range ) for a primitive variable then the compiler will throw exception “possible loss of precision” if we try to provide explicit cast then the compiler will accept it but narrowed down the value using two’s complement method. Let’s take an example of the byte which has 8-bit storage space and range -128 to 127. In below program we are trying to assign 129 literal value to byte primitive type which is out of range for byte so compiler converted it to -127 using two’s complement method. Refer link for two’s complement calculation (http://en.wikipedia.org/wiki/Two's_complement)

Java Code: Go to the editor

Reference variable assignment

We can assign newly created object to object reference variable as below

First line will do following things,

• Makes a reference variable named s of type String
• Creates a new String object on the heap memory
• Assigns the newly created String object to the reference variables

You can also assign null to an object reference variable, which simply means the variable is not referring to any object. The below statement creates space for the Employee reference variable (the bit holder for a reference value) but doesn't create an actual Employee object.

Compound Assignment Operators

Sometime we need to modify the same variable value and reassigned it to a same reference variable. Java allows you to combine assignment and addition operators using a shorthand operator. For example, the preceding statement can be written as:

The += is called the addition assignment operator. Other shorthand operators are shown below table

Below is the sample program explaining assignment operators:

• Assigning a value to can be straight forward or casting.
• If we assign the value which is out of range of variable type then 2’s complement is assigned.
• Java supports shortcut/compound assignment operator.

Java Code Editor:

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1. Overview

Simply put, static final variables, also called constants , are key features in Java to create a class variable that won’t change after initialization . However, in the case of a static final object reference, the state of the object may change.

In this tutorial, we’ll learn how to declare and initialize constant variables. Also, we’ll discuss their usefulness.

2. static final Variables

The static keyword associates a variable to a class itself, not to instances of the class.

Furthermore, the final keyword makes a variable immutable. Its value can’t change after initialization.

The combination of the two keywords helps create a constant. They are mostly named using uppercase and underscores to separate words .

2.1. Initializing static final Variables

Here’s an example of how to declare a static final field and assign a value:

Here, we create a class named Bike  with a constant class variable named TIRE and initialize it to two.

Alternatively, we can initialize the variable via a static initializer block:

This will compile without an error:

Here are some key rules for constant variables:

• We must initialize upon declaration or in a static initializer block
• We can’t reassign it after initialization

Attempting to initialize it outside the initialization scope will cause an exception.

Also, we can’t initialize it via the constructor because constructors are invoked when we create an instance of a class. Static variables belong to the class itself and not to individual instances .

2.2. static   final  Objects

We can also create static final object references:

Since the PART reference is constant, it can’t be reassigned:

The code above throws an exception because we assign a new reference to an immutable variable.

However, we can modify the state of the object:

Here, we can change the value of the seat  despite setting it to one initially. We mutate the contents of PART  despite being a constant reference. Only the reference itself is immutable.

Notably, the final  keyword only makes primitive types, String , and other immutable types constant. In the case of an object, it only makes the reference constant, but the state of the object can be altered .

3. Why Constants Are Useful

Using static final variables has several advantages. It provides better performance since its values are inlined at compile time instead of a runtime value lookup .

Moreover, declaring reusable values as constant avoids duplicating literals. Constant can be reused anywhere in the code, depending on the access modifier . A constant with a private access modifier will only be usable within the class.

Additionally, a static final variable of primitive or String type is thread-safe. Its value remains unchanged when shared among multiple threads.

Finally, giving semantic names to constant values increases code readability. Also, it makes code self-documenting. For example, the  java.math package provides constants like PI :

The  Math.PI  encapsulates the mathematical constant value in a reusable way.

4. Conclusion

In this article, we learned how to declare and initialize a constant variable. Also, we highlighted some of its use cases.

A final static variable defines a class-level constant. However, a  static final object may still be mutable, even if the reference can’t change.

As always, the complete source code for the examples is available over on GitHub .

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Assignment, Arithmetic, and Unary Operators

The simple assignment operator.

One of the most common operators that you'll encounter is the simple assignment operator " = ". You saw this operator in the Bicycle class; it assigns the value on its right to the operand on its left:

This operator can also be used on objects to assign object references , as discussed in Creating Objects .

The Arithmetic Operators

The Java programming language provides operators that perform addition, subtraction, multiplication, and division. There's a good chance you'll recognize them by their counterparts in basic mathematics. The only symbol that might look new to you is " % ", which divides one operand by another and returns the remainder as its result.

The following program, ArithmeticDemo , tests the arithmetic operators.

This program prints the following:

You can also combine the arithmetic operators with the simple assignment operator to create compound assignments . For example, x+=1; and x=x+1; both increment the value of x by 1.

The + operator can also be used for concatenating (joining) two strings together, as shown in the following ConcatDemo program:

By the end of this program, the variable thirdString contains "This is a concatenated string.", which gets printed to standard output.

The Unary Operators

The unary operators require only one operand; they perform various operations such as incrementing/decrementing a value by one, negating an expression, or inverting the value of a boolean.

The following program, UnaryDemo , tests the unary operators:

The increment/decrement operators can be applied before (prefix) or after (postfix) the operand. The code result++; and ++result; will both end in result being incremented by one. The only difference is that the prefix version ( ++result ) evaluates to the incremented value, whereas the postfix version ( result++ ) evaluates to the original value. If you are just performing a simple increment/decrement, it doesn't really matter which version you choose. But if you use this operator in part of a larger expression, the one that you choose may make a significant difference.

The following program, PrePostDemo , illustrates the prefix/postfix unary increment operator:

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• Variables and Data Types
• ➤ What is Variable
• ➤ Types of Java Variables
• ➤ Naming conventions for Identifiers
• ➤ Data Type in Java
• ➤ Mathematical operators in Java
• ➤ Assignment operator in Java
• ➤ Arithmetic operators in Java
• ➤ Unary operators in Java
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Assignment Operator in Java with Example

Assignment operator is one of the simplest and most used operator in java programming language. As the name itself suggests, the assignment operator is used to assign value inside a variable. In java we can divide assignment operator in two types :

• Assignment operator or simple assignment operator
• Compound assignment operators

What is assignment operator in java

The = operator in java is known as assignment or simple assignment operator. It assigns the value on its right side to the operand(variable) on its left side. For example :

The left-hand side of an assignment operator must be a variable while the right side of it should be a value which can be in the form of a constant value, a variable name, an expression, a method call returning a compatible value or a combination of these.

The value at right side of assignment operator must be compatible with the data type of left side variable, otherwise compiler will throw compilation error. Following are incorrect assignment :

Another important thing about assignment operator is that, it is evaluated from right to left . If there is an expression at right side of assignment operator, it is evaluated first then the resulted value is assigned in left side variable.

Here in statement int x = a + b + c; the expression a + b + c is evaluated first, then the resulted value( 60 ) is assigned into x . Similarly in statement a = b = c , first the value of c which is 30 is assigned into b and then the value of b which is now 30 is assigned into a .

The variable at left side of an assignment operator can also be a non-primitive variable. For example if we have a class MyFirstProgram , we can assign object of MyFirstProgram class using = operator in MyFirstProgram type variable.

Is == an assignment operator ?

No , it's not an assignment operator, it's a relational operator used to compare two values.

Is assignment operator a binary operator

Yes , as it requires two operands.

Assignment operator program in Java

a = 2 b = 2 c = 4 d = 4 e = false

Java compound assignment operators

The assignment operator can be mixed or compound with other operators like addition, subtraction, multiplication etc. We call such assignment operators as compound assignment operator. For example :

Here the statement a += 10; is the short version of a = a + 10; the operator += is basically addition compound assignment operator. Similarly b *= 5; is short version of b = b * 5; the operator *= is multiplication compound assignment operator. The compound assignment can be in more complex form as well, like below :

List of all assignment operators in Java

The table below shows the list of all possible assignment(simple and compound) operators in java. Consider a is an integer variable for this table.

How many assignment operators are there in Java ?

Including simple and compound assignment we have total 12 assignment operators in java as given in above table.

What is shorthand operator in Java ?

Shorthand operators are nothing new they are just a shorter way to write something that is already available in java language. For example the code a += 5 is shorter way to write a = a + 5 , so += is a shorthand operator. In java all the compound assignment operator(given above) and the increment/decrement operators are basically shorthand operators.

Compound assignment operator program in Java

a = 20 b = 80 c = 30 s = 64 s2 = 110 b2 = 15

What is the difference between += and =+ in Java?

An expression a += 1 will result as a = a + 1 while the expression a =+ 1 will result as a = +1 . The correct compound statement is += , not =+ , so do not use the later one.

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Java's Basic and Shorthand Assignment Operators

Reference assignment, primitive assignment, primitive casting, shorthand assignment operators, basic assignment operator.

Java's basic assignment operator is a single equals-to (=) sign that assigns the right-hand side value to the left-hand side operand. On left side of the assignment operator there must be a variable that can hold the value assigned to it. Assignment operator operates on both primitive and reference types. It has the following syntax: var = expression; Note that the type of var must be compatible with the type of expression .

Chaining of assignment operator is also possible where we can create a chain of assignments in order to assign a single value to multiple variables. For example,

The above piece of code sets the variables x, y, and z to 100 using a single statement. This works because the = is an operator that yields the value of the right-hand expression. Thus, the value of z = 100 is 100, which is then assigned to y , which in turn is assigned to x . Using a "chain of assignment" is an easy way to set a group of variables to a common value.

A variable referring to an object is a reference variable not an object. We can assign a newly created object to an object reference variable as follows:

The above line of code performs three tasks

• Creates a reference variable named st1 , of type Student .
• Creates a new Student object on the heap.
• Assigns the newly created Student object to the reference variable st1

We can also assign null to an object reference variable, which simply means the variable is not referring to any object:

Above line of code creates space for the Student reference variable st2 but doesn't create an actual Student object.

Note that, we can also use a reference variable to refer to any object that is a subclass of the declared reference variable type.

Primitive variables can be assigned either by using a literal or the result of an expression. For example,

The most important point that we should keep in mind, while assigning primitive types is if we are going to assign a bigger value to a smaller type, we have to typecast it properly. In Above piece of code the literal integer 130 is implicitly an int but it is acceptable here because the variable x is of type int . It gets weird if you try 130 to assign to a byte variable. For example, The below piece of code will not compile because literal 130 is implicitly an integer and it does not fit into a smaller type byte x . Likewise, byte c = a + b will also not compile because the result of an expression involving anything int-sized or smaller is always an int .

Casting lets us convert primitive values from one type to another (specially from bigger to smaller types). Casts can be implicit or explicit. An implicit cast means we don't have to write code for the cast; the conversion happens automatically. Typically, an implicit cast happens when we do a widening conversion. In other words, putting a smaller thing (say, a byte ) into a bigger container (like an int ). Remember those "possible loss of precision" compiler errors we saw during assignments. Those happened when we tried to put a larger thing (say, an int ) into a smaller container (like a byte ). The large-value-into-small-container conversion is referred to as narrowing and requires an explicit cast, where we tell the compiler that we are aware of the danger and accept full responsibility.

As a final note on casting, it is very important to note that the shorthand assignment operators let us perform addition, subtraction, multiplication or division without putting in an explicit cast. In fact, +=, -=, *=, and /= will all put in an implicit cast. Below is an example:

In addition to the basic assignment operator, Java also defines 12 shorthand assignment operators that combine assignment with the 5 arithmetic operators ( += , -= , *= , /= , %= ) and the 6 bitwise and shift operators ( &= , |= , ^= , <<= , >>= , >>>= ). For example, the += operator reads the value of the left variable, adds the value of the right operand to it, stores the sum back into the left variable as a side effect, and returns the sum as the value of the expression. Thus, the expression x += 2 is almost the same x = x + 2 .

The difference between these two expressions is that when we use the += operator, the left operand is evaluated only once. This makes a difference when that operand has a side effect. Consider the following two expressions a[i++] += 2; and a[i++] = a[i++] + 2; , which are not equivalent:

In this tutorial we discussed basic and shorthand (compound) assignment operators of Java. Hope you have enjoyed reading this tutorial. Please do write us if you have any suggestion/comment or come across any error on this page. Thanks for reading!

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Avoid self-assigned variables

Why you should care.

There is no reason to re-assign a variable to itself. Either this statement is redundant and should be removed, or the re-assignment is a mistake and some other value or variable was intended for the assignment instead.

How we detect

This Code Insight counts one occurrence each time a variable is re-assigned to itself.

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Java 8 interview questions, download pdf.

Java, originally evolved from the Oak language, was born in early 1996 with its major version as Java 1 or JDK 1.0. Java was initially designed and developed by Sir James Gosling at Sun Microsystems. Java 8 or JDK 8.0 is one of the major releases of the Java programming language in 2014. It is also known by the codename Spider. Java is an open-source project and is currently managed by Oracle Corporation.

This article would walk you through the Java 8 interview questions for freshers and experienced, scope, and opportunities.

Java 8 Interview Questions for Freshers

1. what is the lambda expression in java and how does a lambda expression relate to a functional interface.

Lambda expression is a type of function without a name. It may or may not have results and parameters. It is known as an anonymous function as it does not have type information by itself. It is executed on-demand. It is beneficial in iterating, filtering, and extracting data from a collection.

As lambda expressions are similar to anonymous functions, they can only be applied to the single abstract method of Functional Interface. It will infer the return type, type, and several arguments from the signature of the abstract method of functional interface.

2. What are the various categories of pre-defined function interfaces?

Function: To transform arguments in returnable value.

Predicate: To perform a test and return a Boolean value.

Consumer: Accept arguments but do not return any values.

Supplier: Do not accept any arguments but return a value. 

Operator: Perform a reduction type operation that accepts the same input types.

3. What are some standard Java pre-defined functional interfaces?

Some of the famous pre-defined functional interfaces from previous Java versions are Runnable, Callable, Comparator, and Comparable. While Java 8 introduces functional interfaces like Supplier, Consumer, Predicate, etc. Please refer to the java.util.function doc for other predefined functional interfaces and its description introduced in Java 8.

Runnable: use to execute the instances of a class over another thread with no arguments and no return value. 

Callable: use to execute the instances of a class over another thread with no arguments and it either returns a value or throws an exception.

Comparator: use to sort different objects in a user-defined order

Comparable: use to sort objects in the natural sort order

4. What are static methods in Interfaces?

Static methods, which contains method implementation is owned by the interface and is invoked using the name of the interface, it is suitable for defining the utility methods and cannot be overridden.

5. What is the default method, and why is it required?

A method in the interface that has a predefined body is known as the default method. It uses the keyword default. default methods were introduced in Java 8 to have 'Backward Compatibility in case JDK modifies any interfaces. In case a new abstract method is added to the interface, all classes implementing the interface will break and will have to implement the new method. With default methods, there will not be any impact on the interface implementing classes. default methods can be overridden if needed in the implementation. Also, it does not qualify as synchronized or final.

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6. Can a functional interface extend/inherit another interface?

A functional interface cannot extend another interface with abstract methods as it will void the rule of one abstract method per functional interface. E.g:

It can extend other interfaces which do not have any abstract method and only have the default, static, another class is overridden, and normal methods. For eg:

7. What are functional or SAM interfaces?

Functional Interfaces are an interface with only one abstract method. Due to which it is also known as the Single Abstract Method (SAM) interface. It is known as a functional interface because it wraps a function as an interface or in other words a function is represented by a single abstract method of the interface.

Functional interfaces can have any number of default, static, and overridden methods. For declaring Functional Interfaces @FunctionalInterface annotation is optional to use. If this annotation is used for interfaces with more than one abstract method, it will generate a compiler error.

8. What is MetaSpace? How does it differ from PermGen?

PremGen: MetaData information of classes was stored in PremGen (Permanent-Generation) memory type before Java 8. PremGen is fixed in size and cannot be dynamically resized. It was a contiguous Java Heap Memory.

MetaSpace: Java 8 stores the MetaData of classes in native memory called 'MetaSpace'. It is not a contiguous Heap Memory and hence can be grown dynamically which helps to overcome the size constraints. This improves the garbage collection, auto-tuning, and de-allocation of metadata.

9. What are the significant advantages of Java 8?

• Compact, readable, and reusable code.
• Less boilerplate code.
• Parallel operations and execution.
• Can be ported across operating systems.
• High stability.
• Stable environment.
• Adequate support

10. In which programming paradigm Java 8 falls?

• Object-oriented programming language.
• Functional programming language.
• Procedural programming language.
• Logic programming language

11. Describe the newly added features in Java 8?

Here are the newly added features of Java 8:

Java 8 Interview Questions for Experienced

1. what is the basic structure/syntax of a lambda expression.

Lambda expression can be divided into three distinct parts as below:

1. List of Arguments/Params:

(String name) 

A list of params is passed in () round brackets. It can have zero or more params. Declaring the type of parameter is optional and can be inferred for the context. 

2. Arrow Token:

->  Arrow token is known as the lambda arrow operator. It is used to separate the parameters from the body, or it points the list of arguments to the body. 3. Expression/Body:

A body can have expressions or statements. {} curly braces are only required when there is more than one line. In one statement, the return type is the same as the return type of the statement. In other cases, the return type is either inferred by the return keyword or void if nothing is returned.

2. What are the features of a lambda expression?

Below are the two significant features of the methods that are defined as the lambda expressions: 

• Lambda expressions can be passed as a parameter to another method. 
• Lambda expressions can be standalone without belonging to any class.

3. What is a type interface?

Type interface is available even in earlier versions of Java. It is used to infer the type of argument by the compiler at the compile time by looking at method invocation and corresponding declaration.

4. What are the types and common ways to use lambda expressions?

A lambda expression does not have any specific type by itself. A lambda expression receives type once it is assigned to a functional interface. That same lambda expression can be assigned to different functional interface types and can have a different type.

For eg consider expression s -> s.isEmpty() :

Predicate<String> stringPredicate = s -> s.isEmpty();   Predicate<List> listPredicate = s -> s.isEmpty(); Function<String, Boolean> func = s -> s.isEmpty(); Consumer<String> stringConsumer = s -> s.isEmpty();

Common ways to use the expression

Assignment to a functional Interface —> Predicate<String> stringPredicate = s -> s.isEmpty(); Can be passed as a parameter that has a functional type —> stream.filter(s -> s.isEmpty()) Returning it from a function —> return s -> s.isEmpty() Casting it to a functional type —> (Predicate<String>) s -> s.isEmpty()

5. In Java 8, what is Method Reference?

Method reference is a compact way of referring to a method of functional interface. It is used to refer to a method without invoking it. :: (double colon) is used for describing the method reference. The syntax is class::methodName

Integer::parseInt(str) \\ method reference

str -> Integer.ParseInt(str); \\ equivalent lambda

6. What does the String::ValueOf expression mean?

It is a static method reference to method Valueof() of class String. It will return the string representation of the argument passed.

7. What is an Optional class?

Optional is a container type which may or may not contain value i.e. zero(null) or one(not-null) value. It is part of java.util package. There are pre-defined methods like isPresent(), which returns true if the value is present or else false and the method get(), which will return the value if it is present.

8. What are the advantages of using the Optional class?

Below are the main advantage of using the Optional class: 

It encapsulates optional values, i.e., null or not-null values, which helps in avoiding null checks, which results in better, readable, and robust code It acts as a wrapper around the object and returns an object instead of a value, which can be used to avoid run-time NullPointerExceptions.

9. What are Java 8 streams?

A stream is an abstraction to express data processing queries in a declarative way. 

A Stream, which represents a sequence of data objects & series of operations on that data is a data pipeline that is not related to Java I/O Streams does not hold any data permanently. The key interface is java.util.stream.Stream<T> . It accepts Functional Interfaces so that lambdas can be passed. Streams support a fluent interface or chaining. Below is the basic stream timeline marble diagram:

10. What are the main components of a Stream?

Components of the stream are:

• A data source
• Set of Intermediate Operations to process the data source
• Single Terminal Operation that produces the result

11. What are the sources of data objects a Stream can process?

A Stream can process the following data:

• A collection of an Array.
• An I/O channel or an input device.
• A reactive source (e.g., comments in social media or tweets/re-tweets) 
• A stream generator function or a static factory.

12. What are Intermediate and Terminal operations?

Intermediate Operations:

• Process the stream elements.
• Typically transforms a stream into another stream.
• Are lazy, i.e., not executed till a terminal operation is invoked.
• Does internal iteration of all source elements.
• Any number of operations can be chained in the processing pipeline.
• Operations are applied as per the defined order.
• Intermediate operations are mostly lambda functions.

Terminal Operations:

• Kick-starts the Stream pipeline.
• used to collect the processed Stream data.

13. What are the most commonly used Intermediate operations?

Filter(Predicate<T>) - Allows selective processing of Stream elements. It returns elements that are satisfying the supplied condition by the predicate.

map(Funtion<T, R>) - Returns a new Stream, transforming each of the elements by applying the supplied mapper function.= sorted() - Sorts the input elements and then passes them to the next stage.

distinct() - Only pass on elements to the next stage, not passed yet.

limit(long maxsize) - Limit the stream size to maxsize.

skip(long start) - Skip the initial elements till the start.

peek(Consumer) - Apply a consumer without modification to the stream.

flatMap(mapper) - Transform each element to a stream of its constituent elements and flatten all the streams into a single stream.

14. What is the stateful intermediate operation? Give some examples of stateful intermediate operations.

To complete some of the intermediate operations, some state is to be maintained, and such intermediate operations are called stateful intermediate operations. Parallel execution of these types of operations is complex.

For Eg: sorted() , distinct() , limit() , skip() etc. 

Sending data elements to further steps in the pipeline stops till all the data is sorted for sorted() and stream data elements are stored in temporary data structures.

15. What is the most common type of Terminal operations?

• collect() - Collects single result from all elements of the stream sequence.
• count() - Returns the number of elements on the stream.
• min() - Returns the min element from the stream.
• max() - Returns the max element from the stream.
• anyMatch() , noneMatch() , allMatch() , ... - Short-circuiting operations.
• Takes a Predicate as input for the match condition.
• Stream processing will be stopped, as and when the result can be determined.
• forEach() - Useful to do something with each of the Stream elements. It accepts a consumer.
• forEachOrdered() - It is helpful to maintain order in parallel streams.

16. What is the difference between findFirst() and findAny()?

17. How are Collections different from Stream?

Collections are the source for the Stream. Java 8 collection API is enhanced with the default methods returning Stream<T> from the collections.

18. What is the feature of the new Date and Time API in Java 8?

• Immutable classes and Thread-safe 
• Timezone support
• Fluent methods for object creation and arithmetic
• Addresses I18N issue for earlier APIs
• Influenced by popular joda-time package
• All packages are based on the ISO-8601 calendar system

19. What are the important packages for the new Data and Time API?

• time-zones 
• Java.time.format
• Java.time.temporal
• java.time.zone

20. Explain with example, LocalDate, LocalTime, and LocalDateTime APIs.

• Date with no time component
• Default format - yyyy-MM-dd (2020-02-20)
• LocalDate today = LocalDate.now();  // gives today’s date
• LocalDate aDate = LocalDate.of(2011, 12, 30); //(year, month, date)
• Time with no date with nanosecond precision
• Default format - hh:mm:ss:zzz (12:06:03.015) nanosecond is optional
• LocalTime now = LocalTime.now();  // gives time now
• LocalTime aTime2 = LocalTime.of(18, 20, 30); // (hours, min, sec)

LocalDateTime

• Holds both Date and Time
• Default format - yyyy-MM-dd-HH-mm-ss.zzz (2020-02-20T12:06:03.015)
• LocalDateTime timestamp = LocalDateTime.now(); // gives timestamp now
• //(year, month, date, hours, min, sec)
• LocalDateTime dt1 = LocalDateTime.of(2011, 12, 30, 18, 20, 30);

21. Define Nashorn in Java 8

Nashorn is a JavaScript processing engine that is bundled with Java 8. It provides better compliance with ECMA (European Computer Manufacturers Association) normalized JavaScript specifications and better performance at run-time than older versions.

22. What is the use of JJS in Java 8?

As part of Java 8, JJS is a command-line tool that helps to execute the JavaScript code in the console. Below is the example of CLI commands:

JAVA>jjs jjs> print("Hello, Java 8 - I am the new JJS!") Hello, Java 8 - I am the new JJS! jjs> quit() >>

All in all, Java is a prevalent programming language securing the second rank in popularity in both TIOBE and PYPL programming language ranking. The world's leading tech giants like Twitter, LinkedIn, Amazon, PayPal, etc., use Java to build their web apps and backend web systems. Java is also one of the primary languages used to develop Android apps; an operating system backed and promoted by Google.

As of today, there are 1,751,661 questions around Java on StackOverflow and 123,776 Java public repositories on GitHub and continuously increasing. Considering Java 8 to be one of the most stable versions, there are immense career opportunities and scope in the same. Just understand the concepts, implement them and get ready for the interviews!

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Java 8 mcqs.

What would be the output of the following code

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Lambdas vs. Anonymous Inner classes - what is false?

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Self assignment check in assignment operator

In C++, assignment operator should be overloaded with self assignment check.

For example, consider the following class Array and overloaded assignment operator function without self assignment check.

If we have an object say a1 of type Array and if we have a line like a1 = a1 somewhere, the program results in unpredictable behavior because there is no self assignment check in the above code. To avoid the above issue, self assignment check must be there while overloading assignment operator. For example, following code does self assignment check.

References: http://www.cs.caltech.edu/courses/cs11/material/cpp/donnie/cpp-ops.html

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Multiple assignment at once in java

In python you can do this:

Is there an equivalent in java?

4 Answers 4

tl;dr: No, there isn't such a thing in Java.

You can assign initial values to variables like this:

But if your want (1, 2, 3) to be the result of a method call, this is not possible in Java. Java does not allow returning multiple values.

Python allows this:

The main point, why this does not work in Java is, that the left hand side (LHS) of the assignment must be one variable:

You can not assign to a tuple on the LHS as you can in Python.

• 1 python is not a big bad guy - it returning one value, in case of OP example - tuple. But it supporting unboxing a tuple to variables. java not support such thing. –  Reishin Commented Nov 5, 2019 at 12:21

If you want (1,2,3) to be the result of a method call, you can use an array:

• 1 What about the type of this array? What if is more complex than int[] ? –  user1907906 Commented Nov 16, 2014 at 13:21
• @user1907906 See the generics in Java. –  f1nch Commented Apr 20, 2022 at 7:56

I realize this is an old post, but I could point out a way that comes somewhat close to this.

Using the OP's example (This could obviously use multiple types instead of three ints, but I'm going with the original example),

Now at this point I realize you haven't actually ASSIGNED this to three local variables (or member variables) as you would have liked, however you do have a local variable you can use as though you had... like:

The advantages here are that this is quite terse, hardly more work than the python example and safer/clearer/easier to read; as is I'd be really happy with this!

Perhaps more important though is that as you go on you will realize that this mini-class should have been a real class all along since the values are going to be somewhat associated since they are from the same function!

You can change what you have to a real class with simple editor refactors--replace member access with getter/setter, make members private, extract the class into it's own file and you have a full class!

Chances are that you'll eventually figure out that your original function f() should have been a member (or constructor) of this class in the first place!

By the way, the disadvantage is that this will fully trigger some Java programmers that don't understand that rules were meant to be broken--if you have old coders who are insistent on stuff that seems pedantic (rule-obsessed) it's best not to try this because it'll make their head explode (all over you, most likely).

As I noted in this other question , if your goal is specifically to return multiple values from a function, in Java 16+ you can accomplish something similar to this using a record type:

This will let you return any set of types, with named fields, at the expense of having to add a line to declare the record. This won't really help with assignments like (i, j) = (j, i) however.

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