Precedence rules tell in what order operations are done. For example,
the rules tell you that
2+3*4 is 14, not 20.
Every programmer should know the basic rules of precedence. For operators not covered by the basic rules, it is considered good style to use parentheses to indicate the order of operations, even when those parentheses are not necessary; this makes your code more readable by programmers who do not have the following table memorized.
Entries nearer the top of the table have higher precedence (are done first); entries on the same line of the table have equal precedences.
(parameters) [indices] .
expr++ expr-- Method call, array index, field/method access, postincrement, postdecrement
++expr --expr +expr -expr ! ~
Preincrement, predecrement, unary plus, unary minus, not, bitwise complement
Constructor call, cast
* / %
Multiply, divide, modulus
<< >> >>>
Left shift, right shift, right shift with zero fill
< > <= >= instanceof
Less than, greater than, less than or equal to, greater than or equal to, class or interface membership
Test if equal, test if not equal
Bitwise exclusive or
Logical or condition ? expr : expr Shortcut if-else
+= -= *= /= %=
^= &= |= <<= >>=
assignment with operation