Since readLine will return a string, how exactly are we checking for null? The assignment operator in Java returns the assigned value like it does, e. So here, readLine will be executed, and it's return value stored in line. That value is then checked against nulland if it is nullthe loop will terminate. Assignment Operators. At run time, the result of the assignment expression is the value of the variable after the assignment has occurred.
Here, you assigned whatever returned from that to line and check if the line variable is null or not. Learn more. Return value of assignment operation in Java Ask Question. Asked 3 years, 9 months ago. Active 6 months ago. Viewed 13k times. Matthias Braun Active Oldest Votes. Mureinik Mureinik k 29 29 gold badges silver badges bronze badges. It's not quite accurate to say that they "return" anything.
They are an expression that has a value.Java Assignment Statement
Assignment expressions are evaluated to their assignment value. Drew Beres Drew Beres 1 1 gold badge 6 6 silver badges 20 20 bronze badges. Assignment Operators At run time, the result of the assignment expression is the value of the variable after the assignment has occurred.
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Assignment Statements in Java
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 referencesas discussed in Creating Objects. 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 following program, ArithmeticDemotests the arithmetic operators.
You can also combine the arithmetic operators with the simple assignment operator to create compound assignments. By the end of this program, the variable thirdString contains "This is a concatenated string. The following program, UnaryDemotests the unary operators:. But if you use this operator in part of a larger expression, the one that you choose may make a significant difference. All rights reserved. Hide TOC.
Language Basics. Unary plus operator; indicates positive value numbers are positive without this, however.Java Assignment Operators are classified into two categories, such as simple and compound assignment operators. Assignment operators, as the name says, are used for assigning the values to the variables involved in the operations. Simple assignment operators handle plain uncomplicated operations like addition, subtraction, multiplication and division.
The value of the right side must be of the same data type that has been defined in the left side. There are various task operators. First, we are going to see and check the working of the Simple Assignment operator with the help of a Java program. The program includes assigning two values to number 1 and number 2 and then printing it in the output to show that the values have been assigned to the numbers. When we execute the print statement, we get the following as output.
We are able to see that the two numbers which have been initialized earlier have been printed. Both the numbers were initialized with value 5. Here, we are going to check the working of the compound assignment operator.
The following are the list of compound assignment operators. The above mentioned are the four basic compound assignment operators that are present.
There are other compound assignment operators which are present such as:. In this article, we are going to check the first four compound assignment operators in detail along with the other operators. The basic advantage of compound assignment operators is that it saves a lot of amount of code within the program in Java language.
This operator is used to add numbers to a variable continuously throughout the entire loop. We are going to see a program in which we have the sum of the first ith natural number with the help of a loop. In the for loop we are going to use a Compound additional operator. We see that when we enter the value as 10, that is, we get the sum of the first 10 natural numbers as This program can be used to delete a number from an existing bigger number.
In the next program, we are going to see the deletion of numbers from a bigger number In the sample code, we see that the number 5 is entered and from the numberthe sum until 5 is subtracted, we get the answer as This program can be used to multiply numbers up to a certain number which is entered by the user. We see a program that is used to print the multiplication of a certain number by numbers inside a for loop.
We enter the number as 5 and then we see that the result that is shown is the multiplication of the number with numbers below than that. In other words, this program shows the factorial of a number in simple terms.
Assignment Operators in Java
We see the output of the program in the below screen. In this case, we are going to see the division of a number using the division operator. We will input the value of the numerator and divide it by 10 and produce the output to the user. In the program, we input as a number and we divide it by 10 using Compound Division Assignment operator. We get the output finally as 10 as shown in the below screenshot.
In the below program, we are going to see the working of the remaining operators which are present.Java programs store data values in variables. When a programmer creates a variable in a Java application, he declares the type and name of the variable, then assigns a value to it. The value of a variable can be altered at subsequent points in execution using further assignment operations.
Table of Content
The assignment statement in Java involves using the assignment operator to set the value of a variable. The exact syntax depends on the type of variable receiving a value. In Java, variables are strongly typed. This means that when you declare a variable in a Java program, you must declare its type, followed by its name. The following sample Java code demonstrates declaring two variables, one of primitive-type integer and one of an object type for a class within the application: int num; ApplicationHelper myHelp.
Once a program contains a variable declaration, the kind of value assigned to the variable must be suited to the type declared. These variable declarations could be followed by assignment statements on subsequent lines. However, the assignment operation could also take place on the same line as the declaration.
Assignment in Java is the process of giving a value to a primitive-type variable or giving an object reference to an object-type variable. The equals sign acts as assignment operator in Java, followed by the value to assign. When the assignment statement appears with object references, the assignment operation may also involve object instantiation.
When Java code creates a new object instance of a Java class in an application, the "new" keyword causes the constructor method of the class to execute, instantiating the object. When this line of code executes, the class constructor method executes, returning an instance of the class, a reference to which is stored by the variable. Once a variable has been declared and assigned a value, a Java program can refer to the variable in subsequent processing.
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I know that we cant use assignment operator in if statements in java as we use in any other few languages. Because the "result" of an assignment is the value assigned Effectively, your two snippets are:. This is one reason not to do comparisons with true and false directly. I can't say it's ever happened to me though.
EDIT: Responding to your edit - assignments of all kinds can be used in if statements - and while loops etc, so long as the overall condition expression is boolean. For example, you might have:. While I usually avoid side-effects in conditions, this particular idiom is often useful for the example shown above, or using InputStream.
1.7 Java | Assignment Statements & Expressions
Basically it's "while the value I read is useful, use it. For if you need an expression that evaluates to boolean. The reason the second code works okay is because it is assigning 'b' the value of true, and then comparing to see if b is true or false.
The reason you can do this is because you can do assignment operators inside an if statement, AND you can compare against a boolean by itself. It would be the same as doing if true. In java, you don't have implicit casting. So non-boolean values or not automatically transformed to booleans. In the first case, the result of the statements is an int, which is non-boolean, which will not work. The last case, the result is boolean, which can be evaluated in an if-statement. The rule is not that "assignment can't be used in an if statement", but that "the condition in an if statement must be of type boolean ".
An assignment expression produces a value of the type being assigned, so Java only permits assignment in an if statement if you're assigning a boolean value. Learn more. Asked 10 years, 1 month ago. Active 7 years, 11 months ago. Viewed 10k times. MPelletier GuruKulki GuruKulki It's not a bad idea to get in the habit of putting the constant first in your if statements Jones Mar 6 '10 at Ollie: opinions widely differ on that one.
As far as readability is concerned, this is a bad idea. Furthermore, it offers no benefit in languages such as Java since no confusion can arise here. Jones Mar 11 '10 at Compound-assignment operators provide a shorter syntax for assigning the result of an arithmetic or bitwise operator. They perform the operation on the two operands before assigning the result to the first operand. The following are all possible assignment operator in java:. At run time, the expression is evaluated in one of two ways.
Depending upon the programming conditions:. Examples : Resolving the statements with Compound assignment operators. We all know that whenever we are assigning a bigger value to a smaller data type variable then we have to perform explicit type casting to get the result without any compile-time error.
If we did not perform explicit type-casting then we will get compile time error. But in the case of compound assignment operators internally type-casting will be performed automatically, even we are assigning a bigger value to a smaller data-type variable but there may be a chance of loss of data information. The programmer will not responsible to perform explicit type-casting. Because here 6. Refer: When is the Type-conversion required?
Explanation: In the above example, we are using normal assignment operator.
Here we have to do type-casting to get the result. Explanation: In the above example, we are using compound assignment operator. This article is contributed by Bishal Kumar Dubey.
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Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above. Writing code in comment? Please use ide. The following are all possible assignment operator in java: 1. Load Comments.Operators constitute the basic building block to any programming language. Java too provides many types of operators which can be used according to the need to perform various calculation and functions be it logical, arithmetic, relational etc.
They are classified based on the functionality they provide. Here are a few types:. These operators are used to assign values to a variable. The left side operand of the assignment operator is a variable and the right side operand of the assignment operator is a value.
The value on the right side must be of the same data-type of the operand on the left side otherwise the compiler will raise an error. This means that the assignment operators have right to left associativity, i. The general format of assignment operator is. Note: In many cases, the assignment operators can be combined with other operators to build a shorter version of the statement called Compound Statement. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.
See your article appearing on the GeeksforGeeks main page and help other Geeks. Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below. Writing code in comment? Please use ide. Assignment Operators. String name. Output: num is assigned: 10 name is assigned: GeeksforGeeks. Chinmoy Lenka. Check out this Author's contributed articles. Load Comments.