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The if Statement The if Statement The if Statement The if Statement An example of an if statement: The if statement has the following syntax: if (sum < 0) System.out.print (“less”); System.out.println (“ OK”); The condition must be a boolean expression. It must evaluate to either true or false. if is a Java reserved word if ( condition ) statement; The condition sum < 0 is evaluated. If the condition is true, less OK is printed. If it is not, OK is printed. If the condition is true, the statement is executed. If it is false, the statement is skipped. 6 5 The if-else if else Statement Boolean Expressions Boolean Expressions An else clause can be added to an if statement to make an if-else statement A condition often uses one of Java's equality operators or relational operators, which all return boolean results: if ( condition ) statement1; else statement2; == equal to != not equal to < less than > greater than = greater than or equal to If the condition is true, statement1 is executed; if the condition is false, statement2 is executed One or the other will be executed, but not both Note the difference between the equality operator (==) and the assignment operator (=) 8 7
Block Statements Block Statements The if-else if else Statement Several statements can be grouped together into a block statement A block is delimited by braces : { … } if (sum < 0) System.out.print (“less”); else System.out.print (“more”); System.out.println (“ OK”); When the value of sum is -99 , it prints less OK When the value of sum is 23 , it prints more OK 10 9 Nested if Statements Nested if Statements Block Statements Block Statements There could be an if statement within another if or an else clause Example These are called nested if statements if (sum < 0) System.out.print (“less”); System.out.println (“ OK”); An else clause is matched to the last unmatched if (no matter what the indentation implies) Braces can be used to specify the if statement to which an else clause belongs if (sum < 0) { System.out.print (“less”); System.out.println (“ OK”); } When the value of sum is 5, The 1st prints OK. The 2nd prints nothing at all. 12 11
Page 1: Outline Conditional Statements •
Page 5 and 6: The switch Statement The switch Sta
Page 7 and 8: Comparing Strings Comparing Strings
Page 9 and 10: Assignment Operators Assignment Ope
Page 11 and 12: The while Statement The while State
Page 13: Choosing a Loop Structure Choosing

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