Use the else statement to specify a block of code to be executed if the condition is false.
if (condition
) {
// block of code to be executed if the condition is true
} else {
// block of code to be executed if the condition is false
}
You already know that Java supports the usual logical conditions from mathematics:
You can use these conditions to perform different actions for different decisions.
Java has the following conditional statements:
if to specify a block of code to be executed, if a specified condition is trueelse to specify a block of code to be executed, if the same condition is falseelse if to specify a new condition to test, if the first condition is falseswitch to specify many alternative blocks of code to be executedVery often, in programming, you will need a data type that can only have one of two values, like:
For this, Java has a boolean data type, which can store true or false values.
The Java Math class has many methods that allows you to perform mathematical tasks on numbers.
The Math.max(x,y) method can be used to find the highest value of x and y:
Math.max(5, 10);
Because strings must be written within quotes, Java will misunderstand this string, and generate an error:
String txt = "We are the so-called "Vikings" from the north.";
The solution to avoid this problem, is to use the backslash escape character. Continue reading Java Special Characters
WARNING!
Java uses the + operator for both addition and concatenation.
Numbers are added. Strings are concatenated.
If you add two numbers, the result will be a number:
int x = 10;
int y = 20;
int z = x + y; // z will be 30 (an integer/number)
If you add two strings, the result will be a string concatenation : Continue reading Java Numbers and Strings
The + operator can be used between strings to combine them. This is called concatenation:
String firstName = "John";
String lastName = "Doe";
System.out.println(firstName + " " + lastName);
Strings are used for storing text.
A String variable contains a collection of characters surrounded by double quotes:
Create a variable of type String and assign it a value:
String greeting = "Hello";
Operators are used to perform operations on variables and values.
In the example below, we use the + operator to add together two values:
int x = 100 + 50;
Although the + operator is often used to add together two values, like in the example above, it can also be used to add together a variable and a value, or a variable and another variable:
int sum1 = 100 + 50; // 150 (100 + 50)
int sum2 = sum1 + 250; // 400 (150 + 250)
int sum3 = sum2 + sum2; // 800 (400 + 400)
Java divides the operators into the following groups:
Type casting is when you assign a value of one primitive data type to another type.
In Java, there are two types of casting:
byte -> short -> char -> int -> long -> float -> doubledouble -> float -> long -> int -> char -> short -> byte