Java Toturial 3 - Control Flow

 

1. Conditional Statements(IF)

• 
  Conditional statements execute a block or set of other statements only if certain conditions are met.
  if (name == "Fred")
  {x = 4;}
  else
  {x = 20;};
  Whenthe conditional if statement is used only to make an assignment to onevariable, you can use the terse C conditional operator.
  x = (name == "Fred") ? 4 : 20;

1. Loops (FOR,WHILE)

• For statements allow a set of statements to be repeated or looped through a fixed number of times.
• The round bracket contains initializer(s) ; conditional test ;incrementer(s). If more than one initializer or incrementer is usedthey are separated with commas. The test condition is checked prior toexecuting the block. The incrementing is completed after executing theblock.
• for (int i=1; i<=15; i++) { document.writeln("#"+i); };
• While statements allow a set of statements to be repeated or looped until a certain condition is met.
• The test condition is checked prior to executing the block
• int i = 0;while (i<=5) { document.writeln("#"+i); i = i + 1; };
• DoWhile statements allow a set of statements to be repeated or loopeduntil a certain condition is met. The test condition is checked afterexecuting the block.
• int i = 1;do { document.writeln("#"+i); i = i + 1; } while (i<=5);

1. The Switch Statement(switch case)

• Switch(or case) statements are used to select which statements are to beexecuted depending on a variable's value matching a label. default isused for the else situation.

switch (selection)
{
case '1': System.out.println("You typed a 1"); break;
case '2': System.out.println("You typed a 2"); break;
case '3': System.out.println("You typed a 3"); break;
case '4': System.out.println("You typed a 4"); break;
default : System.out.println("Oops!, that was an invalid entry.");
};

1. Continue, Break and Return

• Continuestatements are used in looping statements to force another iteration ofthe loop before reaching the end of the current one.
• Break statements are used in looping and 'switch' statements to force an abrupt termination or exit from the loop or switch.
• Return statements are used to force a quick exit from a method. They are also used to pass values back from methods.

1. Command Line Arguments

• Command line arguments are accessible through the args array.
• The array does not include the interpreter java command or the class name and the count starts at 0.
• Each argument is passed as a string but may be converted to other types

 

 

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