Java

ลำดับตอนที่ #4 : Java Ⅱ - Booleans and Conditions

Booleans and Comparison Operators

Booleans

          First, we'll learn a new data type called boolean. A boolean can have only two values, true and false. Be careful not to use quotes for true and false!

Comparison Operators

          Comparison operators compare two values, then return true or false. x == y judges whether x and y have the same value. The result will be true if they do, and false if they don't. x != y is the opposite. Make sure not to confuse = (assign) and == (compare).

Printing Booleans

          You can print booleans as well. However, you shouldn't enclose true and false in quotes, so be careful! As comparison operators return boolean values, they also get printed as true or false.

Comparison Operators

          Just like math, you can use < and > to compare numbers. You can also use >= and <= if you want to make them inclusive.

Logical Operators

&& (AND)

          Logical operators are used to express relations like AND, OR, and NOT. && is used to express AND , and it can be used to combine conditions. For example, condition1 && condition2 will return true only when both condition1 and condition2 are true.

| | (OR)

          || is used for OR, and it can also be used to combine conditions. For instance, condition1 || condition2 will return true if either condition1 or condition2 is true. Take a look at the examples below!

! (NOT)

          ! is used for NOT, and it can be used to negate a condition. For example, the condition !(x >= 30) becomes true when x is smaller than 30 and false when x is greater than or equal to 30.

Logical Operators Review

          Let's review logical operators using the two simple examples below. && results in true only when both values are true while || becomes true if either one of them is true. Make sure to remember them to master logical operators!