CHAPTER 15: Expressions

Previous

Java Language

Index

Next

15.27 Constant Expression

ConstantExpression:

	Expression

A compile-time constant expression is an expression denoting a value of primitive type or a String that is composed using only the following:

• Literals of primitive type and literals of type String
• Casts to primitive types and casts to type String
• The unary operators + , - , ~ , and ! (but not ++ or -- )
• The multiplicative operators * , / , and %
• The additive operators + and -
• The shift operators << , >> , and >>>
• The relational operators < , <= , > , and >= (but not instanceof )
• The equality operators == and !=
• The bitwise and logical operators & , ^ , and |
• The conditional-and operator && and the conditional-or operator ||
• The ternary conditional operator ? :
• Simple names that refer to final variables whose initializers are constant expressions
• Qualified names of the form TypeName . Identifier that refer to final variables whose initializers are constant expressions

Compile-time constant expressions are used in case labels in switch statements (S14.9) and have a special significance for assignment conversion (S5.2).

Examples of constant expressions:

true
(short)(1*2*3*4*5*6)
Integer.MAX_VALUE / 2
2.0 * Math.PI
"The integer " + Long.MAX_VALUE + " is mighty big."