| Old Syntax ( : ) | New Syntax( -> ) | |
|---|---|---|
| Allows zero or more individual statements or zero or more code blocks.
Examples (all valid):
case 0:
case 1: stmt1; stmt2;
case 2: { <code block1>} { <code block 2> }
|
Allows either exactly one statement or exactly one code block. Examples (all invalid):
case 0 -> //invalid, empty case
case 2 -> stmt1; stmt2; //invalid, more than one statement
case 4 -> { } { }//invalid, more than one block
|
|
| Selector expression type | Limited to: byte, short, int, char, and long and their wrappers,
String, and enums Not Allowed: boolean, float, and double |
Limited to: byte, short, int, char, and long and their wrappers,
String, and enums Not Allowed: boolean, float, and double |
| Case label constant type | Must be compatible with selector expression type. null is allowed in Java 21 but only if the switch is exhaustive. | Must be compatible with selector expression type. null is allowed in Java 21 but only if the switch is exhaustive. |
| case label |
Allows a single case constant. | Allows multiple case constants separated by comma. Example:
case 1, 2 -> { }
|
| default label | Not required | Not required |
| Order of switch labels | No restriction | No restriction |
| break | Needed only to prevent fall through |
Prohibited when a switch label is associated with a single statement. Allowed within the code block associated with a switch label but is redundant. |
| yield | Not allowed |
Not allowed |
| exhaustive | Not neccessary | Not neccessary |
| Old Syntax ( : ) | New Syntax( -> ) | |
|---|---|---|
| Allows one expression or one code block. Examples: case 0: yield 1; //valid, returns 1 case 3: yield "aa".length(); //valid, returns 2. case 2: "a".length(); //syntactically valid, no yield required for non-void method call but falls through without returning a value case 1: 1; //invalid, missing yield keyword |
Allows one expression or one code block. Examples: case 1 -> 1; //valid, returns 1, no yield required case 3 -> "a".length();//valid, returns 1, no yield required case 4 -> { yield 1; }//valid, yield is required in a block case 0 -> //invalid, missing expression case 2 -> yield 1; //invalid, must not write yield |
|
| Selector expression type | Limited to: byte, short, int, char, and long and their wrappers,
String, and enums Not Allowed: boolean, float, and double |
Limited to: byte, short, int, char, and long and their wrappers,
String, and enums Not Allowed: boolean, float, and double |
| Case label constant type | Must be compatible with selector expression type. null is allowed in Java 21 but only if the switch is exhaustive. | Must be compatible with selector expression type. null is allowed in Java 21 but only if the switch is exhaustive. |
| case label |
Allows a single case constant. | Allows multiple case constants separated by comma. Example: case 1, 2 -> 1; |
| default label | Not required if already exhaustive | Not required if already exhaustive |
| Order of switch labels | No restriction | No restriction |
| break | Prohibited | Prohibited |
| yield | Required to return value |
Required only when returning a value from a code block. Otherwise prohibited. |
| exhaustive | Neccessary | Neccessary |
| Old Syntax ( : ) | New Syntax( -> ) | |
|---|---|---|
| Selector expression type | All types are allowed | All types are allowed |
| Type of case constants | Must be compatible with the type of the selector expression | Must be compatible with the type of the selector expression |
| exhaustive | Necessary | Necessary |
| default label |
Not required if already exhaustive |
Not required if already exhaustive |
| Order of switch labels |
Must follow the rule of dominance | Must follow the rule of dominance |
| Fall through behavior | Not allowed. So, break is required after each switch label. | Fall through is not possible. break is prohibited. |