在Java中中断文件txt

Question

my data in notepad 1,2,3,4,5,6,7,8,9,10... why when str ==5 using break does not good work, my data is supposed stop when in numbers 5 ...just display 1,2,3,4,5,6,7,8,9,10...

 Scanner sc = new Scanner (new File("c:/Users/ASUS/Desktop/Numbers.txt"));
            while (sc.hasNextInt()){
                int str = sc.nextInt();
                for (int i=0; i<str; i++){
                    if (str == 5);
                    break;
                }

                System.out.print(str+ " ");
            }       
            sc.close();
        }
    }

Answer 1

You need to get rid of the ; after if(str==5); There should be no ;.

for (int i=0; i<str; i++){
    if (str == 5)
    {
        break;
    }
}

The thing is your loop isn't actually doing any processing. You are looping a max of 6 times but you aren't doing anything in your loop. You aren't changing your output at all the loop is completely useless in this case...

You are just breaking out of the for loop not the while loop. If you want to break out of the while loop you should do like this:

Scanner sc = new Scanner (new File("c:/Users/ASUS/Desktop/Numbers.txt"));
            while (sc.hasNextInt()){
                int str = sc.nextInt();
                System.out.print(str+ " ");
                if (str == 5)
                {
                   break;
                }
            }       
            sc.close();
        }
}

Answer 2

You could just change your code to be easier and do:

 Scanner sc = new Scanner (new File("c:/Users/ASUS/Desktop/Numbers.txt"));
            int str = sc.nextInt();
            while (sc.hasNextInt() && str != 6){
                System.out.print(str+ " ");
                str = sc.nextInt();
            }       
            sc.close();
        }
    }

Answer 3

Just to respond with the example, the ; after your if ends that if statement. Use braces {}

if(str==5){
    break;
}

so:

 Scanner sc = new Scanner (new File("c:/Users/ASUS/Desktop/Numbers.txt"));
        while (sc.hasNextInt()){
            int str = sc.nextInt();
                if (str == 5){
                    break;
                }

            System.out.print(str+ " ");
        }       
        sc.close();
    }
}

An alternative way to do it would be to load the entire line, split on , and then iterate through the following array and print out if there is a 5 and break if you find it

Answer 4

I think the solution is to loop as long as the number has not been found.

boolean foundFive = false;
Scanner sc = new Scanner (new File("c:/Users/ASUS/Desktop/Numbers.txt"));
while (sc.hasNextInt() && !foundFive) {
    int number = sc.nextInt();
    System.out.print(number+ " ");
    if (number == 5) {
        foundFive = true;
    }
}       
sc.close();