Logical

Logical expressions are combinations of relational expressions.

A logical expression compares two true/false values and results in a single true/false value.

Logical Operators¶

Name	Operator	Example	Evaluates to `true` when...
AND	`&&`	`a && b`	both a and b are true
OR	`\|\|`	`a \|\| b`	either a or b is true
AND¹	`&`	`a & b`	both a and b are true
OR¹	`\|`	`a \| b`	either a or b is true

_{[1] we rarely use this operator}

&& - AND¶

Both of the AND operator's operands must be true for the logical expression to evaluate to true.

boolean maleOlderThan65 = sex == 'M' && age > 65;

|| - OR¶

If either of the OR operator's operands are true, the expression will evaluate to true.

boolean lessThan18orGreaterThan65 = age < 18 || age > 65;

Practice Exercise¶

Each side of a logical expression must evaluate to a boolean result. The example below would generate a compiler error.

  int age = 21;
  boolean isRegistered = true;
  boolean isRegisteredAnd21 = isRegistered && age = 21; //error

See the problem? The right side of the && mistakenly uses the = operator, which results in a number. We cannot compare boolean && int. This code will not compile.

Drill¶

Expressions/src/drills/Logical.java * Add code to check if the salary is in the range of min and max and assign that value to isExpectedSalary. * Add code to check and output whether the salary is "dreamy," where dreamy means it is more than $10,000 greater than your max. * Add code to check and output whether the salary is "laughable," where laughable means it is at least $5,000 less than your minimum salary requirement.

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