try-catch语句嵌套

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class TryCatchCatchs {

	public static void main(String[] args) {
		Date date = readDate();
		System.out.println("日期 = " + date);
	}

	private static Date readDate() {
		//IO文件输入流
		FileInputStream readfile = null;
		//IO文件输出流
		InputStreamReader ir = null;
		BufferedReader in= null;
		try {
			//通过FileInputStream读取一个文件文件
			readfile = new FileInputStream("readme.txt");
			ir = new InputStreamReader(readfile);
			in = new BufferedReader(ir);
			//try-catch嵌套
			try {
				//读取文件中的一行数据
				String str = in.readLine();
				if(str == null){
					return null;
				}
				//初始化时间格式
				DateFormat df = new SimpleDateFormat("yyyy-MM-dd");
				//格式化时间格式
				Date date = df.parse(str);
				return date;
			} catch (ParseException e) {
				System.out.println("处理ParseException...");
				e.printStackTrace();
			}
			
		} catch (FileNotFoundException e) {
			System.out.println("处理FileNotFoundException...");
			e.printStackTrace();
		} catch (IOException e){
			System.out.println("处理IOException...");
			e.printStackTrace();
		}
		return null;
	}

}