How to use java.util.Scanner class to read input?

Question

I have a question about using java.util.Scanner class to read input.

Below is my coding without using java.util.Scanner class to read input:

         public class NewTry {
          public static float[][] clone(float[][] a) throws Exception {
          float b[][] = new float[a.length][a[0].length];

           for (int i = 0; i < a.length; i++) {
            for (int j = 0; j < a[0].length; j++) {
                b[i][j] = a[i][j];
              }
           }
           return b;
         }

         public static void main(String args[]) {


          float[][] a = new float[][] { { 1.513f, 2.321f, 3.421f }, { 4.213f, 5.432f, 6.123f },
        { 7.214f, 8.213f, 9.213f } };



          try {
    float b[][] = clone(a);
    for (int i = 0; i < a.length; i++) {
        for (int j = 0; j < a[0].length; j++) {
            System.out.print(b[i][j] + " ");
        }
         System.out.println();
          }
      } catch (Exception e) {
          System.out.println("Error!!!");
    }
        }
    }

Show output without using java.util.Scanner:

      run:
     1.513 2.321 3.421 
     4.213 5.432 6.123 
     7.214 8.213 9.213 
     BUILD SUCCESSFUL (total time: 3 seconds)

My problem is how to add java.util.Scanner class to read input without default float number in the coding? Is using array run scanner?

Actually I want the sample output same like the below （the float number must key in myself）：

       run:
       Type nine float numbers two-dimensional array of similar type and size with line breaks, end 
       by"-1":
       1.513
       2.321
       3.421 
       4.213
       5.432 
       6.123 
       7.214
       8.213 
       9.213 
       -1


       The result is:

       1.513 2.321 3.421 
       4.213 5.432 6.123 
       7.214 8.213 9.213 
       BUILD SUCCESSFUL (total time: 11 second) 

Hope someone can guide me or modified my coding to add java.util.Scanner class to read input .Thanks.

Answer 1

Check this out

 public static void main(String args[]) {

            Scanner sc = new Scanner (System.in);
            System.out.println ("Type nine float numbers two-dimensional array of similar type and size with line breaks, end by -1:");
            float[][] a = new float[3][3];
            for (int i=0; i<3; i++){
                for (int j=0; j<3; j++){
                    String line = sc.nextLine();
                    if ("-1".equals(line)){
                        break;
                    }
                    a[i][j]=Float.parseFloat(line);
                }
            }

            System.out.println("\n The result is:");

            try {
                float b[][] = clone(a);
                for (int i = 0; i < a.length; i++) {
                    for (int j = 0; j < a[0].length; j++) {
                        System.out.print(b[i][j] + " ");
                    }
                    System.out.println();
                }
            } catch (Exception e) {
                System.out.println("Error!!!");
            }
        }

You should define a new Scanner (sc) and then loop 3 x 3 times until you read all input. If the user enters -1 the loop ends. Note that you do not need to exit when 9 numbers are entered.

Also each user input is read as a line and not as a token, and then is parsed into a Float. If the user enters a String that is not a float number then it throws an Exception.

Sample:

Type nine float numbers two-dimensional array of similar type and size with line breaks, end by -1:
1.1
1.2
1.3
2.1
2.2
2.3
3.1
3.2
3.3

The result is:
1.1 1.2 1.3 
2.1 2.2 2.3 
3.1 3.2 3.3 

Answer 2

Scanner scan =new Scanner(System.in);
float[][] a = new float[3][3];

for(int i =0 ;i<3;i++) {
   for(int j=0; j<3; i++) {
      a[i][j] =scan.Float();
   }
}