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Evaluating expressions in java

Содержание
  1. What is Expression in Java?
  2. Simple Expressions
  3. Compound Expressions
  4. How to Evaluate Expression in Java?
  5. Types of Operators
  6. Operator Precedence
  7. Associativity Rules
  8. Types of Expressions in Java
  9. Infix Expression
  10. Postfix Expression
  11. Prefix Expression
  12. Examples
  13. Expressions That Produce a Value
  14. Expressions That Assign a Variable
  15. Java Expression with No Results
  16. Java Statements
  17. Difference between Statements and Expressions in Java
  18. Learn More
  19. Conclusion

What is Expression in Java?

Java Course - Mastering the Fundamentals

Here marks=90 is an expression that returns an int value. Example:

Here in this example, a+b-3.4 is an expression.

Simple Expressions

A simple expression is a literal method call or variable name without any usage of an operator. For example:

A simple expression in java has a type that can either be a primitive type or a reference type. In this example, 43 is a 32-bit integer, java is a string, 32L is a long 64-bit integer, etc.

Compound Expressions

It generally involves the usage of operators. It comprises one or more simple expressions, which are then integrated into a larger expression by using the operator. Consider another example in order to understand more clearly.

How to Evaluate Expression in Java?

Types of Operators

  • Additive operators It increases or decreases the numeric value by addition or subtraction. Here are a few additive operators:
    • Addition — syntax: operand1 + operand2 , it returns sum. For example 3+2=5.
    • Subtraction — syntax: operand1 — operand2 , it returns subtraction. For example 5-3=2.
    • Postdecrement — syntax: variable — — , it subtracts 1 from the variable’s value and returns the original value.
    • Postincrement- syntax: variable + + , it adds 1 to the variable’s value, stores and returns the result in the variable.
    • Predecrement- syntax: — — variable , it adds 1 to the variable’s value, stores the result in the variable and returns the updated value.
    • Preincrement — syntax: ++variable , it adds 1 to the variable, stores and returns the incremented value.
    • String concatenation- syntax: operand1 + oeprand2 , it returns the concatenation of two strings.
    • Bitwise AND- syntax: operand1 & operand2 , here operands can be the type of integer or char. The resultant bit is set to 1 when the corresponding operand’s bit is 1, else 0.
    • Bitwise complement- syntax: ~ operand , it flips the bit of operand. If the bit is 1 then it flips to 0 and wise-versa.
    • Bitwise exclusive OR- syntax: operand1 ^ operand2 , the resultant bit is set to 1 if the corresponding bit of the operand is 1 and the other operand’s bit is 0, else 0.
    • Bitwise inclusive OR- syntax: operand1 | operand2 , here the bit is set to 1 when both or either operand’s bit is 1 else the resultant bit is set to 0.
    • Conditional- syntax: operand1 ? operand2 : operand3 , where operand1 is of type boolean when operand1 is true, it returns operand2 else it returns operand3. Example: boolean status = true; int statusInt = (status)? 1 : 0;.
    • Conditional AND- syntax: operand1 && operand2 , here each operand is of type boolean and it returns true when both the operands are true, else false. It is also known as short-circuiting, for example: false && true= false.
    • Conditional OR- syntax: operand1 || operand2 , when one of the operands is true, it returns true, else it returns false. Example: true || false= true
    • Equality — syntax: operand1 == operand2 , where both operands must be comparable. It returns when both the values are true, else false. Example: ‘a’ == ‘b’, it returns false
    • Inequality — syntax: operand1 != operand2 , for example: ‘a’ != ‘b’, it returns true.
    • Logical AND- syntax: operand1 & operand2, here each operand is of type boolean. It returns true if both the operands are true, else false. For example, true and false= false.
    • Logical complement- syntax: !operand, it flips the value of operand, i.e if the value of the operand is true then the output is false, and vice-versa.
    • Multiplication — syntax: operand1 * operand2 . It returns the output as a multiplication of two values. Example, «3*4=12».
    • Division — syntax: operand1 / operand2 . It divides operand1 by operand2. For example, 15/5=3.
    • Remainder — syntax: operand1 % operand2 . It divides operand1 by operand2 leaving behind the remainder. For example, 14%3= 2.
    • Greater than- syntax: operator1 > operator2 . It returns true if operand1 > operand2, else false.
    • Greater than or equal to- syntax: operator1 >= operator2 . It returns true if operator1 is greater than or equal to operator2, else false.
    • Less than- syntax: operand1 < operand2 . It returns true if operand1 is less than operand2, else false.
    • Less than or equal to- syntax: operator1
    • Type checking- syntax: operand1 instanceof operator2 . Here operator1 is an object and operator2 is a class. It returns true if operator1 is an object of class operand2, else false.
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