Day03_Java condition of the self-Java if statement

The concept of conditional statements

Conditional statements can be given a determination condition, and determines whether the condition is satisfied, performs different operations according to the determination result, so as to change the order of execution of the code, the more functionality during program execution.

Conditional statements if

Single if statement:
Implementation process
  • First, determine the relationship between the expression to see the result is true or false
  • If the statement is true on the implementation of the body
  • If false statement is not executed body

Execution Flow

demand

Illustrates the flow of execution if statement

Code

public  class Demo02IfTest {
     public  static  void main (String [] args) {
         // definition of two variables 
        int A = 66 ;
         int B = 66 ;
         // variables determining if, a == b is a relational expression 
        if (A = = B) {
             // loop 
            System.out.println ( "digits equal to 2" ); 
        } 
        // the following if condition code does not belong 
        System.out.println ( "Code executed after the if statement" ); 

    } 
}

Results of the

Standard format if ... else:
Implementation process
  • First, determine the relationship between the expression to see the result is true or false
  • If the statement is true on the implementation of 1
  • If false statement on the implementation of 2

Execution Flow

demand

Illustrates the execution flow if else

Code

public  class Demo03IfElseTest {
     public  static  void main (String [] args) {
         // determines the given data is odd or even
         // define the variable 
        int A =. 1 ;
         IF (A% 2 == 0 ) { 
            System.out.println ( "A is an even number" ); 
        } the else { 
            System.out.println ( "A is an odd number" ); 
        } 
        System.out.println ( "end" ); 
    } 
}

Results of the

Extended if ... else if ... else format:

Implementation process
  • First, determine the relationship between the expression 1 to see the result is true or false
  • If the statement is true on the implementation of 1
  • If it is false to continue to determine the relationship between the expression 2 to see the result is true or false
  • If the statement is true on the implementation of 2
  • If it is false to continue to determine the relationship between the expression ... see the result is true or false
  • If there is no relationship between the expression is true, then the statement is executed body n + 1.

 Execution Flow

demand

Illustrate execution flow of if..else if ... else

Specifies the test scores to determine student grades 80-89 90-100 good good good 70-79 60-69 60 or less pass fail

Code

public class Demo05IfElsePractise {
    public static void main(String[] args) {
        int score = 120;
        if (score >= 90 && score <= 100) {
            System.out.println("优秀");
        } else if (score >= 80 && score < 90) {
            System.out.println("好");
        } else if (score >= 70 && score < 80) {
            System.out.println("良");
        } else if(Score> = 60 && Score <70 ) { 
            System.out.println ( "pass" ); 
        } the else  IF (Score> = 0 && Score <60 ) { 
            System.out.println ( "fail" ); 
        } the else {
             // separate treatment pathological case outside the boundary 
            System.out.println ( "data error" ); 
        } 
    } 
}

Results of the

note:

In some simple applications, if the statement is a ternary operator can be used interchangeably. For example: selecting the maximum value between the digital
 
 
 

 

 

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Origin www.cnblogs.com/wurengen/p/11516212.html