如何分支到循环的指定部分？

Question

int a = 0;
int b = 0;
int c = 0;
Scanner sc = new Scanner(System.in);
for (int i = 0; i < 6; i++) {
    b = sc.nextInt();
    a =+ b;
    c =+ (a + 1);
    if (c < 20) {
        i = 2;
    }
}

if I have lines numbered from 0 to 6 inside the loop, the loop would be so if c is less than 20, it repeats the operation "c=+(a+1);" until it breaks out of the loop by c>=20.

this is a simplified code from my program, mine is GUI. every time I run the code, it freezes.

Answer 1

You can tag a loop and do break or continue instructions, but you need design the flow, it is not possible to go into specified line, because java don't use goto instruction. You can only switch the flow inside loops by those instructions.

myloopTag: 
for (...; ...; ...) {
    // and you can break current loop by:
    break;

    // or specific (outer) loop by
    break myloopTag;

    // you can also use 'continue' to go to the start of the loop and increment again
    continue;

    // or to 'continue' at a label:
    continue myloopTag;
}

Answer 2

use c+= instead of c=+ . try that, cheers! and b+= instead of b=+ .

Answer 3

You're probably very new to the language. Welcome!

If I understand your description of your intent properly, you want your code to exit the loop when c>=20. Based on your description of numbering your lines and the fact that you have the statement:

if(c<20){
    i=2;
}

it seems that you think that the iterator i in the for loop is related to the line that will be executed*. This is not the case. The iterator i is a variable that simply holds an integer (just like a , b , and c in your code).

I suggest you take a look at a tutorial on for loops . It might be helpful for you to review other language basics as well, like how control flow works (this may be a better one to start with, actually).

*This guess at your intent is further supported by you counting that there are 6 lines and that your loop goes up to 6.