从arraylist打印内容

Question

所以我想弄清楚如何打印我的数组列表的实际内容,而不是内存位置

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Scanner;


public class hw2redo 
{
    public static void main(String args[]) throws FileNotFoundException
    {
         //Scan file for data
         GeometricObject g = null;
         BufferedReader file = new BufferedReader(new FileReader("file.txt"));
            Scanner diskScanner = new Scanner(file);
            //Create dynamic array list
            ArrayList<GeometricObject> list = new ArrayList<GeometricObject>();
            //Scan data and add data to list
            while(diskScanner.hasNext())
            {
                String geolist = diskScanner.nextLine();
                g = recreateObject(geolist);

                list.add(g);

            }

            showObjects(list);

    }
    private static GeometricObject recreateObject(String data)
    {
        GeometricObject object = new GeometricObject(data);
        return object;
    }
    private static void showObjects(ArrayList<GeometricObject> list)
    {
    for(GeometricObject o : list)
      System.out.println(o);
    }


}
class GeometricObject
{

    public GeometricObject(String data) {
        // TODO Auto-generated constructor stub
    }

}

所以这是我的代码.我尝试过使用toString()和Arrays.toString(),但它们似乎不适用于arraylist(我试过,因为它们在我的常规数组上工作).

我收到的输出是

// Output
GeometricObject@55f96302
GeometricObject@3d4eac69
GeometricObject@42a57993
GeometricObject@75b84c92
GeometricObject@6bc7c054
GeometricObject@232204a1

这很好,因为我很接近,我只需要弄清楚如何打印实际内容.

我在file.txt中寻找的内容是

Circle,green,false,4.0
Circle,blue,false,2.0
Circle,blue,true,7.0
Rectangle,orange,true,10.0,6.0
Rectangle,green,false,5.0,11.0
Rectangle,red,true,14.0,12.0

任何帮助将非常感激.谢谢!

Answer 1

你toString班上需要一个方法:

class GeometricObject
{

    private String data;

    public GeometricObject(String data) {
        this.data = data;
    }

    @Override
    public String toString() {
        return data;
    }

}

没有覆盖,你正在使用Object.toString().toString正如您所观察到的,Object 打印出对象的类名和哈希码.