此程序在没有名为“test object.to”的现有文件时运行。这个程序的输出是“io捕获”。为什么？

import java.io.*;

public class Test 
{
    public static void main (String [] args)
    {
        TestObject testObject = new TestObject("Test Object");

        try
        {
            saveTestObject(testObject);
        }
        catch (FileNotFoundException fnf)
        {
            System.out.println("FNF caught");
        }
        catch (IOException io)
        {
            System.out.println("IO caught");
        }
    }

    static void saveTestObject(TestObject to)  throws FileNotFoundException, IOException
    {
        ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(to.name + ".to"));
        oos.writeObject(to);
        oos.close();
    }
}

class TestObject
{
    String name;

    TestObject(String s)
    {
        name = s;
    }
}