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When an unlabeled continue statement is encountered, it causes the current iteration of the current loop to be terminated and the nextiteration to begin.
A labeled continue statement can cause control to be passed to the next iteration of an outer enclosing loop in a nested loopsituation.
An example of the use of an unlabeled switch statement is given in the next section.
This section discusses the use of labeled break and continue statements.
One way to describe the behavior of a labeled break in Java is to say: "Break all the way out of the labeled statement."
Syntax of a labeled statement
To begin with, the syntax of a labeled statement is a label followed by a colon ahead of the statement as shown in Figure 7 .
| Figure 7 . Syntax of a labeled statement. |
|---|
myLabel: myStatement; |
The label can be any legal Java identifier.
Behavior of labeled break
The behavior of a labeled break can best be illustrated using nested switch statements. For a comparison oflabeled and unlabeled switch statements, consider the program shown in Listing 6 named switch1 , which does not use a labeled break. Even though this program has a labeled statement, that statement isnot referenced by a break . Therefore, the label is of no consequence.
| Listing 6 . The program named switch1.java. |
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/*File switch1.java
This is a Java application which serves as a baseline
comparison for switch2.java which uses a labeled break.Note that the program uses nested switch statements.
The program displays the following output:Match and break from here
Case 6 in outer switchDefault in outer switch
Beyond switch statements********************************************************/
class switch1 { //define the controlling classpublic static void main(String[] args){ //main method//Note that the following labeled switch statement is
// not referenced by a labeled break in this program.// It will be referenced in the next program.
outerSwitch: switch(5){//labeled outer switch statementcase 5: //execute the following switch statement
//Note that the code for this case is not followed// by break. Therefore, execution will fall through
// the case 6 and the default.switch(1){ //inner switch statement
case 1: System.out.println("Match and break from here");
break; //break with no labelcase 2: System.out.println(
"No match for this constant");break;
}//end inner switch statementcase 6: System.out.println("Case 6 in outer switch");
default: System.out.println("Default in outer switch");
}//end outer switch statementSystem.out.println("Beyond switch statements");
}//end main}//End switch1 class. |
After reviewing switch1.java , consider the same program named switch2.java shown in Listing 7 , which was modified touse a labeled break.
The outputs from both programs are shown in the comments at the beginning of theprogram. By examining the second program, and comparing the output from the second program with the first program, you should be able to see how the use ofthe labeled break statement causes control to break all the way out of the labeled switch statement.
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