Operators - Java Tutorial 5.0 英文版

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Operators

An operator performs a function on one, two, or three operands. An operator that requires one operand is called a unary operator. For example, ++ is a unary operator that increments the value of its operand by 1. An operator that requires two operands is a binary operator. For example, = is a binary operator that assigns the value from its right operand to its left operand. Finally, a ternary operator is one that requires three operands. The Java programming language has one ternary operator, ?:, which is a shorthand if-else statement.

The unary operators support either prefix or postfix notation. Prefix notation means that the operator appears before its operand.

operator op             //prefix notation

Postfix notation means that the operator appears after its operand.

op operator             //postfix notation

All the binary operators use infix notation, which means that the operator appears between its operands.

op1 operator op2        //infix notation

The ternary operator is also infix; each component of the operator appears between operands.

op1 ? op2 : op3         //infix notation

In addition to performing the operation, an operator returns a value. The return value and its type depend on the operator and the type of its operands. For example, arithmetic operators, which perform basic arithmetic operations such as addition and subtraction, return numbers — the result of the arithmetic operation. The data type returned by an arithmetic operator depends on the type of its operands: If you add two integers, you get an integer back. An operation is said to evaluate to its result.

Operators are divided into the following categories:

• Arithmetic Operators
• Relational and Conditional Operators
• Shift and Bitwise Operators
• Assignment Operators
• Other Operators

We end this lesson with Summary of Operators and Questions and Exercises: Operators.

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