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Easy Learn Java: Programming Articles, Examples and Tips - Page 364


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'else' Not Required

Go to all tips in General Java

'else' is not required

It is not necessary to have the else part of an if statement. Maybe only 50% of the time there is an else part.

Form

The if statement without an else has this form:
   if (condition) {
      do this if the condition is true
   }

Example

Here is a paintComponent() method with an if statement without an else clause.
public void paintComponent(Graphics g) {
  super.paintComponent(g);  // draw background etc.
  if (marks < 50) {
     g.setColor(Color.red);
  }
  g.drawString("Score = " + marks, 10, 50);
}
When the paintComponent() method begins, the Graphics context g uses Color.black by default. Therefore there is no need to set the color to black.

7 comments | Printer Friendly Page  Send to a Friend | Score: 0
Posted by jalex on Friday, May 27, 2005 (00:00:00) (3935 reads)

if Statement - Overview

Go to all tips in General Java

Purpose

The purpose of the if statement is to make decisions, and execute different parts of your program depending on a true/false value.

General Forms

The if statement has this form:

do these statements
if (condition) {
    do this clause if the condition is true
}
do these statements afterwards

or

do these statements
if (condition) {
    do this clause if the condition is true
} else {
    do this clause if the condition is false
}
do these statements afterwards

It is good programming style to always write the curly braces, {}, altho they are not needed if the clause contains only a single statement.

Condition is true or false

The value of condition must be true or false (ie, a boolean value). It is often a comparison.

. . .
if (marks < 60) {
    JOptionPane.showMessageDialog(null, "This is terrible");
} else {
    JOptionPane.showMessageDialog(null, "Not so bad");
}
. . .

The code above will display one of two dialogs, depending on teh value of marks.



15 comments | Printer Friendly Page  Send to a Friend | Score: 0
Posted by jalex on Thursday, May 26, 2005 (00:00:00) (2583 reads)

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