[Java] Java conditional branch

2 minute read

Introduction

It is still difficult to explain the small difficult parts in sentences, so I will write the basics of what I can do first.

How to write a conditional branch

kane.java


if(Conditional expression){
processing;
  }

** This is the basic form **
Boolean value, comparison operator (==, <Etc.), logical operators (etc.)&&, ||, !) Etc. to write the conditional expression.

block{}

Use when you want to combine multiple processes.
No semicolon is required after ** {}. ** **

kane.java



int x = 40

if (x >= 30) {
   System.out.println("x is 30 or more.");
} else if (x > 20) {
   System.out.println("x is greater than 20 and less than 30.");
} else {
   System.out.println("x is less than 20.");
}

//This time it is executed in the first process

You can arrange else if as many as you want, but ** only the first matching condition is executed. ** **

switch statement

When the value of the condition matches the value of case, the process is executed.
Note that it is easy to forget the ** colon (:) after the case. ** **

kane.java


switch(Condition value) {
case value 1:
processing;
      break;
case value 2:
processing;
      break;
case value 3:
processing;
      break;
}

** When the condition value in () and the case value are “==”, the process is executed. **

kane.java


int = x

switch(x % 2) { //Condition value

  case 0: //true
      System.out.println("This is an even number"); //This runs
      break;
  case 1:
      System.out.println("This is odd");
      break;
}

break
Break is extremely important in switch statements. ** Without break **, ** All executed **, break is ** when using switch statements **.
** * If you want to continue processing the case statement, omit break. There is a fall-through, and it is written by omitting the break of the case statement, but at this stage I do not understand how to use it and write it as a word. **

default
Similar to else in an if statement.

kane.java


int number = -1;

 switch(number) {
  case 0:
      System.out.println("0");
      break;
  case 1:
      System.out.println("Is 1");
      break;
  case 2:
      System.out.println("2");
      break;
  default:
      System.out.println("I'm sorry. Once again thank you");
      break;
 }

String type can also be used

kane.java


String number = "zero";

 switch(number) {
  case "zero":
      System.out.println("0");
      break;
  case "Ichi":
      System.out.println("Is 1");
      break;
  case "D":
      System.out.println("2");
      break;
  default:
      System.out.println("I'm sorry. Once again thank you");
      break;
 }

It can be used in the same way as a numerical value.

If the String type is empty, “null”
(A state where there is an irregularity of null other than the state of number = “”, number = “null”, etc.)
In this case, please note that it will not be picked up by default.
** * I don’t understand this either, but leave it as a memo **

At the end

Looking at other posts, I noticed that it becomes easier to see just by changing the indentation of {} and if statement switch statement.
You should also be aware of the number of #s in the table of contents of the post.

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