java學習之switch語句與循環語句

int a = 1,b =2;
switch(a+b){
	case 1:
	System.out.print(1);
	case 3:
	System.out.print(3);
	case 4:
    System.out.print(4);
    default:
    System.out.print(5);
}

345

int a = 2, b = 34;
switch(a + b){
	case 5:
	System.out.println(5);
	break;
    case 6:
    System.out.println(6);
    break;
    default:
    System.out.println(12);
}

12

Scanner a = new Scanner(System.in);
System.out.print("please input a month：");
int month = a.nextInt();
switch(month){
	case 1: case 2: case 3:
	System.out.println("Spring");
	break;
	case 4: case 5: case 6:
	System.out.println("Summer");
	break;
	case 7: case 8: case 9:
	System.out.println("Autumn");
	break;
	case 10: case 11: case 12:
	System.out.println("Winter");
	break;
	default:
	System.out.println("fasle");
}

Scanner a = new Scanner(System.in);
System.out.print("please input a month：");
int month = a.nextInt();
switch(month){
	case 1: 
	case 2:
    case 3:
	System.out.println("Spring");
	break;
	case 4: 
	case 5: 
	case 6:
	System.out.println("Summer");
	break;
	case 7: 
	case 8: 
	case 9:
	System.out.println("Autumn");
	break;
	case 10: 
	case 11: 
	case 12:
	System.out.println("Winter");
	break;
	default:
	System.out.println("fasle");
}

int j;
for (int i = 0; i < 1000; i++) {
	for (j = 2; j < i; j++) 
		if (i % j == 0)
			break;
    if (j == i)
    	System.out.println(i);
}

2
3
5
…

for (int i = 0; i < 1000; i++) {
	if(i == 2)
		System.out.println(2);
    for (int j = 2; j < i; j++) {
    	if(i % j == 0)
        	break;
        if(j == i - 1 )
            System.out.println(i);
     }
}