Assignment Operators
Assignment operators are used to assign values to variables. While
the basic equals sign = is the most common, Java offers "compound"
assignment operators that perform a math operation and assignment in one step.
Assignment Operators List
| Operator | Example | Equivalent To |
|---|---|---|
= |
x = 5 |
x = 5 |
+= |
x += 3 |
x = x + 3 |
-= |
x -= 3 |
x = x - 3 |
*= |
x *= 3 |
x = x * 3 |
/= |
x /= 3 |
x = x / 3 |
%= |
x %= 3 |
x = x % 3 |
Output
Click Run to execute your code
Hidden Type Casting
Compound assignment operators like += have a special feature: they
automatically perform a type cast.
Consider adding an int to a byte (remember, byte +
int results in int):
byte b = 10;
// b = b + 1; // Compile ERROR! (int cannot be converted to byte)
// Correct way with explicit cast:
b = (byte)(b + 1);
// SHORTCUT with +=
b += 1; // Works! Cast is implicit.The compiler treats E1 op= E2 as
E1 = (Type of E1)(E1 op E2).
Watch Out: Because of hidden casting, you might trigger an
overflow without realizing it!
byte b = 127; b += 1; // b becomes -128 (overflow)
Summary
- Use
=to assign a value. - Use
+=,-=, etc. for cleaner code when modifying a variable by a value. - Compound assignment operators automatically handle type casting, which is convenient but hides potential data loss or overflows.
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