【Java】制御構文ノート

制御構文#

構造化定理##

• 順次
• 分岐
  • if, switch
• 繰り返し
  • while,for

分岐##

• if
• switch

// if構文
int r=new java.util.Random().nextInt(2);
if (r<1){
	System.out.println("This is true by 'if'.");
}else{
	System.out.println("This is false by 'if'.");
}

// switch構文
int s=new java.util.Random().nextInt(3);
switch(s){
	case 0:
		System.out.println("This is Case.0 by 'switch'.");
		break;
	case 1:
		System.out.println("This is Case.1 by 'switch'.");
		break;
	case 2:
		System.out.println("This is Case.2 by 'switch'.");
		break;
	default:
		System.out.println("This is default by 'switch'.");
}

繰り返し##

• while
• do while
• for

// while構文
int w=1;
while(w<4){
	System.out.println("Count No."+w+" by 'while'.");
	w++;
}

// do while構文
int dw=3;
do{
	System.out.println("Count No."+dw+" by 'do while'.");
	dw--;
	System.out.println("Count decrease -1 by 'do while'.");
}while(dw>0);


// for構文
for(int i=1; i<=3; i++){
	System.out.println("Count No."+i+" by 'for'.");
}

「繰り返しの中断」という概念##

• continue：ループを続ける。
• break：ループを抜ける。

// 繰り返しの中断
for(int i=5; i>=1; i--){
	if(i==3){
		continue;
	}
	if(i==2){
		break;
	}
	System.out.println("Count No."+i+" by 'for/continue(3)/break(2)'.");
}

参考書籍#

[スッキリわかるJava入門第２版]
(https://www.amazon.co.jp/dp/B00MIM1KFC/ref=dp-kindle-redirect?_encoding=UTF8&btkr=1)
Pp.098-133.