The
Thebreak
Statementbreak
statement has two forms: labeled and unabeled. You saw the unlabeled form in the previous discussion of theswitch
statement. You can also use an unlabeledbreak
to terminate afor
,while
, ordo-while
loop, as shown in the followingBreakDemo
program:This program searches for the number 12 in an array. Theclass BreakDemo { public static void main(String[] args) { int[] arrayOfInts = { 32, 87, 3, 589, 12, 1076, 2000, 8, 622, 127 }; int searchfor = 12; int i; boolean foundIt = false; for (i = 0; i < arrayOfInts.length; i++) { if (arrayOfInts[i] == searchfor) { foundIt = true; break; } } if (foundIt) { System.out.println("Found " + searchfor + " at index " + i); } else { System.out.println(searchfor + " not in the array"); } } }break
statement, shown in boldface, terminates thefor
loop when that value is found. Control flow then transfers to the print statement at the end of the program. This program's output is:An unlabeledFound 12 at index 4break
statement terminates the innermostswitch
,for
,while
, ordo-while
statement, but a labeledbreak
terminates an outer statement. The following program,BreakWithLabelDemo
, is similar to the previous program, but uses nestedfor
loops to search for a value in a two-dimensional array. When the value is found, a labeledbreak
terminates the outerfor
loop (labeled "search"):class BreakWithLabelDemo { public static void main(String[] args) { int[][] arrayOfInts = { { 32, 87, 3, 589 }, { 12, 1076, 2000, 8 }, { 622, 127, 77, 955 } }; int searchfor = 12; int i; int j = 0; boolean foundIt = false; search: for (i = 0; i < arrayOfInts.length; i++) { for (j = 0; j < arrayOfInts[i].length; j++) { if (arrayOfInts[i][j] == searchfor) { foundIt = true; break search; } } } if (foundIt) { System.out.println("Found " + searchfor + " at " + i + ", " + j); } else { System.out.println(searchfor + " not in the array"); } } }This is the output of the program.
Found 12 at 1, 0Thebreak
statement terminates the labeled statement; it does not transfer the flow of control to the label. Control flow is transferred to the statement immediately following the labeled (terminated) statement.The
Thecontinue
Statementcontinue
statement skips the current iteration of afor
,while
, ordo-while
loop. The unlabeled form skips to the end of the innermost loop's body and evaluates theboolean
expression that controls the loop. The following program,ContinueDemo
, steps through aString
, counting the occurences of the letter "p". If the current character is not a p, thecontinue
statement skips the rest of the loop and proceeds to the next character. If it is a "p", the program increments the letter count.Here is the output of this program:class ContinueDemo { public static void main(String[] args) { String searchMe = "peter piper picked a peck of pickled peppers"; int max = searchMe.length(); int numPs = 0; for (int i = 0; i < max; i++) { //interested only in p's if (searchMe.charAt(i) != 'p') continue; //process p's numPs++; } System.out.println("Found " + numPs + " p's in the string."); } }To see this effect more clearly, try removing theFound 9 p's in the string.continue
statement and recompiling. When you run the program again, the count will be wrong, saying that it found 44 p's instead of 9.A labeled
continue
statement skips the current iteration of an outer loop marked with the given label. The following example program,ContinueWithLabelDemo
, uses nested loops to search for a substring within another string. Two nested loops are required: one to iterate over the substring and one to iterate over the string being searched. The following program,ContinueWithLabelDemo
, uses the labeled form of continue to skip an iteration in the outer loop.class ContinueWithLabelDemo { public static void main(String[] args) { String searchMe = "Look for a substring in me"; String substring = "sub"; boolean foundIt = false; int max = searchMe.length() - substring.length(); test: for (int i = 0; i <= max; i++) { int n = substring.length(); int j = i; int k = 0; while (n-- != 0) { if (searchMe.charAt(j++) != substring.charAt(k++)) { continue test; } } foundIt = true; break test; } System.out.println(foundIt ? "Found it" : "Didn't find it"); } }Here is the output from this program.
Found itThe
The last of the branching statements is thereturn
Statementreturn
statement. Thereturn
statement exits from the current method, and control flow returns to where the method was invoked. Thereturn
statement has two forms: one that returns a value, and one that doesn't. To return a value, simply put the value (or an expression that calculates the value) after thereturn
keyword.The data type of the returmed value must match the type of the method's declared return value. When a method is declaredreturn ++count;void
, use the form ofreturn
that doesn't return a value.The Classes and Objects lesson will cover everything you need to know about writing methods.return;