How to read data from a file and create an object and assign it to an array?

问题

GeometricObjectsData.txt

“CIRCLE”, 1, “blue”, true
“RECTANGLE”, 1, 2, “blue”, true
“RECTANGLE”, 10, 2, “red”, true
“CIRCLE”, 2, “green”
“RECTANGLE”
“CIRCLE”

Driver: I'm a bit confused on how to transfer the above information into an object and then assign it to an array.

import java.io.File;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.Scanner;

public class Driver {
public static void main(String[] args) throws FileNotFoundException {
    Scanner input = new Scanner(new File("C:/Users/Charles/Desktop/GeometricObjectsData.txt"));

    ArrayList<GeometricObject> list = new ArrayList<GeometricObject>();

    while (input.hasNext()) {
        String line = input.nextLine();
        System.out.println(line);
    }
  }
}

I also have created 3 other classes called GeometricObject, Circle, and Recetangle if you want to see the code for them. The information above indicates the type of figure and the given parameters of radius, length, width, color, and filled.

回答1:

As microsby0 said, you could probably split the raw words into arrays. I don't believe there is an easy way to directly convert a raw word into a class name ((Circle)"Circle" doesn't work and is what I believe is confusing you). You should read each array into certain parameters and process them:

/*somewhere else in code:*/ shapeArray[i] = convert(array[0],array[1],...)//where i is some incremental value in a loop

Shape convert(String s, int someNumber,...) {
  Shape c;
  switch(s) {
    case "Circle":
      c = new Circle(...);
    break;
    case "Square"
      ...
    break;
    //and so on
  }

 //more application logic
 return c;
 }

Convert can return a shape which you can assign to an array of shapes. You can always use function(method) 'overloading' to handle different inputs.

回答2:

PSUEDOCODE is used:

I probably wouldn't use a Scanner but

BufferedReader buffer = new BufferedReader(new FileReader(file));

then you would

//this should split the text of each line into an array

String buf[]= null;
    while ((line = buffer.readLine()) != null) {

        resultLine += line + ";";
        buf = resultLine.split(";");

    }
    buffer.close();

then looped through the array buf and do

if(buf[i].startsWith("C"))

then do another split on buf[i] using "," into another array like String arr[]

arr = buf[i].split(",");

then but the elements of the second array in the Circle Class like

Circle circle = new Circle(arr[0],arr[1],etc

then add to an array

Object result[] = new Object[100];
result[0] = circle;

来源：https://stackoverflow.com/questions/26241322/how-to-read-data-from-a-file-and-create-an-object-and-assign-it-to-an-array

标签

java

object

geometry

java.util.scanner