使用扫描仪时没有此类元素异常

Question

I am attempting to read a txt file. I keep getting a "no such element" error and I cannot understand why. My code is,

File myFile = new File(input.txt)
Scanner reader = new Scanner(myFile);

for (int i = 0; i<20; i++)
{
    name[i] = reader.nextLine();
    grade[i] = reader.nextInt();
    reader.nextLine();
    rank[i] = reader.nextInt();
    reader.nextLine();
}
reader.close();

Here is an example of the file format . What am I missing?

Answer 1

This is why using a for loop is a bad idea when reading from a file; you don't know (rather, you shouldn't care for most intents and purposes) how large your file is.

Switch it out for a while loop:

while(reader.hasNext()) {
    // code
}

(Don't forget to advance i in the loop.)

Provided that your tokens are divided up into exact multiples of three, this will read the tokens in without running out of stuff to read from.

Answer 2

Definitely not a good choice to use for loop.

You can try something like this:

int i=0;
int i1=0;
int i2=0;
int i3=0;

while(reader.hasNextLine()) {
    i++;
    if(i==1){
        name[i1]=reader.nextLine();
        i1++;
    }
    if(i==2){
        grade[i2]=Integer.valueOf(reader.nextLine());
        i2++;
    }
    if(i==3){
        rank[i3]=Integer.valueOf(reader.nextLine());
        i3++;
        i=0;
    }
}