Looping

while, do-while, for

The body of the while loop is run only if the expression is true, so it cannot be executed even once:

while(i < 5){...}

The body of the do-while loop is run at least once because the test expression is evaluated only  after executing  the  loop  body.  Also, don't  forget  the  ending  semicolon  after  the  while expression.

do { ... } while(i < 5);

The for loop syntax is:

for(expr1; expr2; expr3)

{

// body

}

expr1 Æ is for initialization, expr2 Æ is the conditional test, and expr3 Æ is the iteration expression. Any of these sections may be omitted and the syntax will still be legal:

for( ; ; ) {} // an endless loop

Decision making

if-else, switch-case

The if-else statement is used for decision-making -- that is, it decides which course of action have to be taken.

if (x == 5) {...} else {..}

The switch statement is also used for decision-making, based on an integer expression. The argument passed to the switch and case statements could be int, char, short, or byte. The argument passed to the case statement could be a literal or a final variable. If no case matches, the default statement (which is optional) is executed.

int i = 1;

switch(i)

{

case 0:

System.out.println("Zero");break; //if break; is omitted case 1: also executed

case 1:

System.out.println("One");break; //if break; is omitted default: also executed

default: System.out.println("Default");break;

}

Branching

break, continue, label:, return

The break statement is needed to exit from a loop or switch statement, while the continue statement is needed to skip just the current iteration and continue with the next. The return is used to return from a function based on a condition. The label statements may lead to unreadable and unmaintainable spaghetti code hence should be avoided.

Exception handling

try-catch-finally, throw

Exceptions may be used to define ordinary flow control. This is a misuse of the idea of exceptions, which are meant only for exceptional conditions and hence should be avoided.