Java Operators
Warning: These notes have been collected from several different sources - each uses different terminology... they may even be contradictory...
The left operand must be a variable, as: x = 5, not: 5 = x
Boolean Expressions (often make comparisons between numbers)
| Operator | Meaning |
|---|
| A = B | value B is assigned to A |
A = = B
(two equal signs in a row) | is A equal to B ? |
| A < B | is A less than B ? |
| A <= B | is A less than or equal to B ? |
| A > B | is A Greater than B ? |
| A >= B | is A Greater than or equal to B ? |
| A != B | is A not equal to B ? |
| ! ( A < B ) | not (A less than B), becomes A greater than B |
Table of Relational Operators
| Operator | Meaning |
|---|
A = = B
(two equal signs in a row) |
is String A exactly equal to String B ?
are they the same object, do they have the same identity? |
| A.equals(B) | compares the values held in each object |
Table of String comparisons
| Operator | Meaning |
|---|
| + | addition |
| - | subtraction |
| * | multiplication |
| / | division |
| % | modulus (the remainder from a division)
10 % 3 is 1, and 10 % 2 is 0 |
| = | means only assignment (not equals) |
+ +
(two plus signs in a row) | increments, adds one to a variable |
| ++counter | means increment before using |
| counter++ | means increment after using |
- -
(two minus signs in a row) | decrements, subtracts one from a variable |
| --counter | use the value, then subtract 1 |
| counter-- | subtract 1, then use the value |
| = | means assignment (not equals) |
| += |
addition with assignment, ( increment sum by 5 )
sum += 5; is the same as sum = sum + 5; |
| -= |
subtraction with assignment, ( decrement sum by 5 )
sum -= 5; is the same as sum = sum - 5; |
| *= |
multiplication with assignment, ( multiply sum by 5 )
sum *= 5; is the same as sum = sum * 5; |
| /= |
division with assignment, ( divide sum by 5 )
sum /= 5; is the same as sum = sum / 5; |
| %= |
modulus with assignment, ( modulate sum by 5 )
sum %= 5; is the same as sum = sum % 5;
sum/5 has a modulus(remainder) of whatever, then sum becomes the whatever |
Table of Other Operators
| Expression | Result | Evaluation Order |
|---|
| true && true | true | both operands evaluated |
| false && true | false | only first operand evaluated |
| true && false | false | both operands evaluated |
| false && false | false | only first operand evaluated |
| true & true | true | both operands evaluated |
| false & true | false | both operands evaluated |
| true & false | false | both operands evaluated |
| false & false | false | both operands evaluated |
| true || true | true | only first operand evaluated |
| false || true | true | both operands evaluated |
| true || false | true | only first operand evaluated |
| false || false | false | both operands evaluated |
| true | true | true | both operands evaluated |
| false | true | true | both operands evaluated |
| true | false | true | both operands evaluated |
| false | false | false | both operands evaluated |
Table of And/Or Operators
| Operator | Meaning |
|---|
A ? B : C
| makes no changes to any of the three operands,
it is like a simple if statement:
if A is true, then B, else C |
The Conditional Operator
|
See
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