Java，将文本分类为行

Question

I'm writing a code that read a text from a file and then sort it into lines of max specific width.

Example: a text that contains "aaaa bbbb cccc dddd"

specified width is 16

so the output should be

aaaa bbbb cccc //width is only 14, if dddd is added, it would be longer than 16.

dddd

My approach: read the text and assign it to a string

Scanner input_OUT = new Scanner(new File("abc"));

PrintStream output = new PrintStream("abc");
.
.


 while (input_OUT.hasNextLine()) {
            str = input_OUT.nextLine();
        }

String s = "";

while(input_OUT.hasNext()) { // get words if it still have

            if (s.length() + input_OUT.next().length() > width) { 
                s = str.substring(0,s.length());
                output.println(s);
                str = str.substring(s.length()+1,str.length());
                s = "";
            }
            else {
                s += input_OUT.next();
            }

        }

Although it compiles. But the file doesn't show any output. I think my code is not right. I know there is options for stringbuild, string split, array. But i'm now allowed to do that.

Answer 1

The first issue is within this loop, assuming there is more than one thing being scanned from the file this approach won't work.

String str;
while (input_OUT.hasNextLine()) {
   str = input_OUT.nextLine();
}

All you are doing is resetting str to the next element scanned.

A better approach would be to store file input into an array of Strings.

String str;   
String S[] = new String[#stringsInFile];
int i = 0;
while (input_OUT.hasNextLine()) {
   str = input_OUT.nextLine();
   S[i] = str;
   i++
}

Now all you have to do is manipulate the array S[] and then output to your output file.

Noted in comments you said you can't an array. Lets just keep adding to S then and allow you to perform manipulations on S . The approach:

 String str;
 String S = "";    
 while (input_OUT.hasNextLine()) {
    str = input_OUT.nextLine();
    S = S +" "+ str; //This will keep adding onto S until hasNextLine is false
 }