📋Preface📋 💝Blog homepage: Red eye aromatherapy_CSDN blog-Big data, computer theory, MySQL field blogger💝 ✍This article was originally created by Zai Xia [Red Eye Aromatherapy], first published on CSDN✍ 🤗The biggest wish in 2022: [Serving millions of technical people]🤗 💝Initial environment address:[ spark environment construction (idea version) - Hongmu aromatherapy - CSDN blog]💝
Environmental requirements
Environment: win10 Development tools: IntelliJ IDEA 2021.2 maven version: 3.6.3
Table of contents
Scala if else branch statement
Create a test class [day1/demo2.scalc], select Object as the type
Scala operators
An operator is a symbol that tells the compiler to perform specified mathematical and logical operations.
Scala has a rich set of built-in operators, including the following types:
- arithmetic operator
- relational operator
- Logical Operators
- bitwise operator
- assignment operator
Next, we will introduce the application of the above operators in detail.
arithmetic operator
The following table lists the arithmetic operators supported by Scala.
Assume variable A is 10 and B is 20:
operator | describe | example |
|---|---|---|
+ | plus | The result of A + B operation is 30 |
- | minus sign | A - B operation result is -10 |
* | Multiplication sign | The result of A * B operation is 200 |
/ | division sign | The result of B / A operation is 2 |
% | Take the remainder | B % A operation result is 0 |
example
package day1
object demo2 {
def main(args: Array[String]) {
var a = 5;
var b = 6;
var c = 7;
var d = 8;
println("a + b = " + (a + b) );
println("a - b = " + (a - b) );
println("a * b = " + (a * b) );
println("b / a = " + (b / a) );
println("b % a = " + (b % a) );
println("c % a = " + (c % a) );
}
}
relational operator
The following table lists the relational operators supported by Scala.
Assume variable A is 10 and B is 20:
operator | describe | example |
|---|---|---|
== | equal | (A == B) evaluates to false |
!= | not equal to | (A != B) evaluates to true |
> | more than the | (A > B) evaluates to false |
< | less than | (A < B) evaluates to true |
>= | greater or equal to | (A >= B) evaluates to false |
<= | less than or equal to | (A <= B) evaluates to true |
example
package day1
object demo2 {
def main(args: Array[String]) {
var a = 5;
var b = 6;
println("a == b = " + (a == b) );
println("a != b = " + (a != b) );
println("a > b = " + (a > b) );
println("a < b = " + (a < b) );
println("b >= a = " + (b >= a) );
println("b <= a = " + (b <= a) );
}
}
Logical Operators
The following table lists the logical operators supported by Scala.
Assume variable A is 1 and B is 0:
operator | describe | example |
|---|---|---|
&& | logic and | (A && B) evaluates to false |
|| | logical or | (A || B) evaluates to true |
! | logical NOT | !(A && B) evaluates to true |
example
package day1
object demo2 {
def main(args: Array[String]) {
var a = true;
var b = false;
println("a && b = " + (a&&b) );
println("a || b = " + (a||b) );
println("!(a && b) = " + !(a && b) );
}
}
assignment operator
The assignment operators supported by the Scala language are listed below:
operator | describe | example |
|---|---|---|
= | A simple assignment operation, specifying that the right operand is assigned to the left operand. | C = A + B Assign the operation result of A + B to C |
+= | Add and then assign, add the left and right operands together and assign to the left operand. | C += A is equivalent to C = C + A |
-= | Subtract and then assign, subtract the left and right operands and then assign to the left operand. | C -= A is equivalent to C = C - A |
*= | Multiply and then assign, the left and right operands are multiplied and then assigned to the left operand. | C *= A is equivalent to C = C * A |
/= | Assign after division, divide the left and right operands and then assign to the left operand. | C /= A is equivalent to C = C / A |
%= | After the remainder is assigned, the remainder of the left and right operands is assigned to the left operand. | C %= A is equivalent to C = C % A |
<<= | Bitwise left shift and then assign | C <<= 2 is equivalent to C = C << 2 |
>>= | Bitwise right shift and then assign | C >>= 2 is equivalent to C = C >> 2 |
&= | Assignment after bitwise AND operation | C &= 2 is equivalent to C = C & 2 |
^= | Bitwise XOR operator and then assignment | C ^= 2 is equivalent to C = C ^ 2 |
|= | Bitwise OR operation and then assignment | C |= 2 is equivalent to C = C | 2 |
example
package day1
object demo2 {
def main(args: Array[String]) {
var a = 5;
var b = 6;
var c = 0;
c = a + b;
println("c = a + b = " + c );
c += a ;
println("c += a = " + c );
c -= a ;
println("c -= a = " + c );
c *= a ;
println("c *= a = " + c );
a = 10;
c = 15;
c /= a ;
println("c /= a = " + c );
a = 10;
c = 15;
c %= a ;
println("c %= a = " + c );
c <<= 2 ;
println("c <<= 2 = " + c );
c >>= 2 ;
println("c >>= 2 = " + c );
c >>= a ;
println("c >>= a = " + c );
c &= a ;
println("c &= 2 = " + c );
c ^= a ;
println("c ^= a = " + c );
c |= a ;
println("c |= a = " + c );
}
}
operator precedence
Example: Calculate multiplication and division first, then addition and subtraction. Parentheses look first.
Check the following table, the priority is descending from top to bottom, the top has the highest priority, and the comma operator has the lowest priority.
category | operator | relevance |
|---|---|---|
1 | () [] | left to right |
2 | ! ~ | right to left |
3 | * / % | left to right |
4 | + - | left to right |
5 | >> >>> << | left to right |
6 | > >= < <= | left to right |
7 | == != | left to right |
8 | & | left to right |
9 | ^ | left to right |
10 | | | left to right |
11 | && | left to right |
12 | || | left to right |
13 | = += -= *= /= %= >>= <<= &= ^= |= | right to left |
14 | , | left to right |
Scala if else branch statement
The if else statement is a code block that is determined to be executed by the execution result (True or False) of one or more statements.
You can simply understand the execution process of the conditional statement through the following figure:
if statement
An if statement consists of a Boolean expression followed by a block of statements.
grammar
The syntax of the if statement is as follows:
package day1
object demo2 {
def main(args: Array[String]) {
var isf=true;
if(isf)
{
// Executes the block of statements if the Boolean expression is true
print("is true");
}
}
}if...else statement
The if statement can be followed by an else statement, and the statement block inside the else can be executed when the Boolean expression is false.
grammar
The syntax of if...else is as follows:
package day1
object demo2 {
def main(args: Array[String]) {
var isf=true;
if(isf)
{
// Executes the block of statements if the Boolean expression is true
print("is true");
}else {
print("is false");
}
}
}if...else if...else statement
The if statement can be followed by an else if...else statement, which is useful in the case of multiple conditional judgment statements.
grammar
if...else if...else syntax is as follows:
package day1
object demo2 {
def main(args: Array[String]) {
var i=100;
if(i>90&i<=100){
print("excellent");
}else if(i>=80){
print("good");
}else if(i>=70){
print("generally");
}else if(i>=60){
print("pass");
}else{
print("failed");
}
}
}
Summarize
This is the end of the Scala Basic Grammar Tutorial about spark II. Operators and Branch Statements (idea version) hope that it can help us.