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));