Logical Operators Part 1

Part of the Fundamentals section of Coddy's Java journey — lesson 22 of 73.

Logical operators are used to check combinations of comparisons that return true or false.

For example the following statement contains two comparisons:

Is 5 greater than 3 and less than 6?

Operator	Meaning	Example
`&&`	And - `true` if all operands are `true`	`a && b`
`\|\|`	Or - `true` if any operand is `true`	`a \|\| b`
`!`	Not - `true` if the operand is `false`	`!a`

Let's see some examples,

5 is bigger than 3 and 1 equals 1,

boolean b1 = (5 > 3) && (1 == 1); // holds true

Explanation: All of the operands are true, so b1 will hold true (and operation is true if both operands are true) .

5 is not equals 4 or five equals 2,

boolean b2 = !(5 == 4) || (5 == 2); // holds true

Explanation: The first operand (5 != 4) is true so b2 is also true (or operation is true if either one of the operands is true)

1 is not equals 1 or false,

boolean b3 = !(1 == 1) || false; // holds false

Explanation: All of the operands are false, so b3 will hold false (or operation).

not (3 bigger than 4),

boolean b4 = !(3 > 4); // holds true

Explanation: The operand is false, so b4 will hold true (not operation).

not (5 bigger than 10 or 5 bigger than 1),

boolean b5 = !(5 > 10 || 5 > 1); // holds false

Explanation: 5 > 10 || 5 > 1 is true (one of the operands is true), so in total b5 is false (not operation).

Challenge

Beginner

You are given a code, Replace the question marks of the variables b1 and b2 so that b3 holds true.

There are many right solutions!

Cheat sheet

Logical operators are used to check combinations of comparisons that return true or false.

Operator	Meaning	Example
`&&`	And - `true` if all operands are `true`	`a && b`
`\|\|`	Or - `true` if any operand is `true`	`a \|\| b`
`!`	Not - `true` if the operand is `false`	`!a`

Examples:

boolean b1 = (5 > 3) && (1 == 1); // true - both operands are true
boolean b2 = !(5 == 4) || (5 == 2); // true - first operand is true
boolean b3 = !(1 == 1) || false; // false - both operands are false
boolean b4 = !(3 > 4); // true - operand is false, so NOT makes it true
boolean b5 = !(5 > 10 || 5 > 1); // false - inner expression is true, NOT makes it false

Try it yourself

public class Main {
    public static void main(String[] args) {
        // Type your code below
        boolean b1 = ?;
        boolean b2 = ?;
        boolean b3 = b1 || b2;
        
        // Don't change the line below
        System.out.println("b3 = " + b3);
    }
}