Java - Operator

Tables

Operators Precedence
postfix expr++ expr–
unary ++expr –expr +expr -expr ~ !
multiplicative * / %
additive + -
shift « » »>
relational < > ⇐ >= instanceof
equality == !=
bitwise AND &
bitwise exclusive OR ^
bitwise inclusive OR |
logical AND &&
logical OR ||
conditional operator (ternary) ? :
assignment = += -= *= /= %= &= ^= |= <<= >>= >>>=

Equality

==

The == operator only compares two references- i.e. whether the two object references point to the same object. The equals function actually compares the two values for equality:

String

A string is by nature an array.

myString.equals("myWord");

null

a == b
a == null
a != b
a != null

Collection

myCollection.size() != 0

In

The Java language doesn't have a IN operator. You must implement it by using another logic.

String

String[] arr = { "Nico", "Fred" };
Set<String> names = new HashSet<String>(Arrays.asList(arr));

System.out.println(names.contains("Nico")); // true
System.out.println(names.contains("Eric")); // false
String s = "Today is Monday";
boolean hasCheese = s.contains("Monday");

Date

Set<Integer> weekendDay = new HashSet<>();
weekendDay.add(Calendar.SATURDAY);
weekendDay.add(Calendar.SUNDAY);
weekendDay.contains(calendar.get(Calendar.DAY_OF_WEEK));

Documentation / Reference


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