一：try catch

package cn.wyj.one;import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;public class Demo1_捕获异常 {public static void main(String[] args) {FileReader reader = null;try {reader = new FileReader("C:/Myjava/project9_常用类/Text.txt");//如果将文件名改成错误的则会  执行   step2 和step3System.out.println("step1");char c1 =(char)reader.read();System.out.println(c1);} catch (FileNotFoundException e) {//子类在前 父类在后// TODO Auto-generated catch blockSystem.out.println("step2");e.printStackTrace();} catch (IOException e) {//父类// TODO Auto-generated catch blocke.printStackTrace();}finally{System.out.println("step3");try {if(reader != null){reader.close();}} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}}