Switch statements in Java
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The switch statement provides an alternative way to execute different blocks of code based on the value of an expression. The switch statement evaluates an expression and attempts to match it to the values specified in each case. If a match is found, control passes to that case's statement list. A break statement at the end of each case causes control to pass to the end of the switch statement after execution. If no break is included, execution will continue into the next case. A default case can also be specified to handle any values not explicitly matched.
Switch statements in Java
- 1. Switch Statements Comparing Exact Values
- 2. The Switch Statement • The switch statement provides another way to decide which statement to execute next • The switch statement evaluates an expression, then attempts to match the result to one of several possible cases • The match must be an exact match. 2 switch ( expression ){ case value1 : statement-list1 case value2 : statement-list2 case value3 : statement-list3 case ... }
- 3. The Switch Statement • Each case contains a value and a list of statements • The flow of control transfers to statement associated with the first case value that matches 3 switch ( expression ){ case value1 : statement-list1 case value2 : statement-list2 case value3 : statement-list3 case ... }
- 4. Switch - syntax • The general syntax of a switch statement is: switch ( expression ){ case value1 : statement-list1 case value2 : statement-list2 case value3 : statement-list3 case ... } switch and case are reserved words If expression matches value3, control jumps to here
- 5. The Switch Statement • The break statement can be used as the last statement in each case's statement list • A break statement causes control to transfer to the end of the switch statement • If a break statement is not used, the flow of control will continue into the next case switch ( expression ){ case value1 : statement-list1 break; case value2 : statement-list2 break; case value3 : statement-list3 break; case ... }
- 6. Switch Example • Examples of the switch statement: switch (option){ case 'A': aCount++; break; case 'B': bCount++; break; case 'C': cCount++; break; }
- 7. Switch – no breaks!!! • Another Example: switch (option){ case 'A': aCount++; case 'B': bCount++; case 'C': cCount++; } switch (option){ case 'A': aCount++; break; case 'B': bCount++; break; case 'C': cCount++; break; }
- 8. Switch - default • A switch statement can have an optional default case • The default case has no associated value and simply uses the reserved word default • If the default case is present, control will transfer to it if no other case value matches • If there is no default case, and no other value matches, control falls through to the statement after the switch
- 9. The switch Statement • Switch with default case: switch (option){ case 'A': aCount++; break; case 'B': bCount++; break; case 'C': cCount++; break; default: otherCount++; break; }
- 10. To Switch or not to Switch • The expression of a switch statement must result in an integral type, meaning an integer (byte, short, int, long) or a char • It cannot be a boolean value or a floating point value (float or double) • The implicit boolean condition in a switch statement is equality • You cannot perform relational checks with a switch statement