[Java] for statement, while statement

A note of what I learned about loop statements.

for statement

Use when you want to repeat the same process a specified number of times using a loop counter or the like. ** ** It is often used for commands such as ** "Output from 1 to 100!" ** Like fizz buzz. It is also compatible with the access of array elements by subscripts, and is also suitable for referencing the contents of an array one by one.

[Format]

for (Initialization formula;Conditional expression; change expression){
Statement to execute;
Statement to execute;
...
}

[Example using a for statement]

(Declaration and initialization of String array)
String[] fighter = {Zero Fighter,Spitfire,Messerschmitt,Lavo chicken};

(Show all the contents of the array arr)
for (int i = 0; i < fighter.length; i++) {                                      
    System.out.println("fighter[" + i + "] … " + arr[i]);
}

【Execution result】

fighter[0]…Zero Fighter
fighter[1]… Spitfire
fighter[2]… Messerschmitt
fighter[3]… Lavo chicken

while statement

** Iterative syntax controlled only by conditional expressions. ** ** Use it properly with the for statement when the number of repetitions such as ** "until the user inputs something" ** is not fixed. In some cases, it may end without moving to make the first judgment.

[Format]

while(Conditional expression){
Statement to execute
}

[Example using a for statement]

//Variable initialization
int i = 1;

//Output numbers from 1 to 10
while (i  <= 10){
  System.out.println( i );
  i++; //If you forget this, an infinite loop will occur, so be careful!
}

【Execution result】

1
2
3
4
5
6
7
8
9
10

About break

You can break out of the loop at that point by writing a break statement.

[Format]

In the if statement etc. ** "When the condition is met, execute the break statement to get out of the loop" **.

for (Initialization formula;Conditional expression; change expression) {
    if (Conditional expression to exit the loop) {
        break; //Exit the loop if the conditions are met
    }
}

[Example using a for statement]

Iterative statements that output numbers from 1 to 10 are stopped when break reaches 7.

    for (int i = 0; i < 10; i++) {
      System.out.println(i);
      if (i == 7) {
        break;
      }
    }

【Execution result】

1
2
3
4
5
6
7

continue statement

The continue statement skips further processing at that point.

[Format]

while (Conditional expression) {
    [Process 1]
    if (Skip condition) {
        continue;   //Process 2 is skipped if the conditions are met
    }
    [Process 2]
}

[Example using continue statement]

Outputs numbers from 1 to 10, and skips processing if it is a multiple of 4 (4 and 8).

    for (int i = 1; i <= 10; i++) {
      if (i % 4 == 0) {
        System.out.println("It is a multiple of 4.");
        continue;
      }
      System.out.println(i);
    }

【Execution result】

1
2
3
It is a multiple of 4.
5
6
7
It is a multiple of 4.
9
10

I think that if you master it, you will be able to express quite complicated things. The infinite loop will be output at a later date.