下面这段程序看不懂 谁能大概解释下的import java.io.*;class J_Exception extends Exception { } public class J_Test { public static void main(String[] args) { try { int i = System.in.read(); if(i == '0') throw new J_Exception(); //手动抛出异常System.out.print("1"); }catch(IOException ex) { System.out.print("2"); }catch(J_Exception ex) { System.out.print("3"); }finally{ System.out.println("4"); } } }为什么当输入0时得到34

下面这段程序看不懂 谁能大概解释下的
import java.io.*;
class J_Exception extends Exception {
} public class J_Test {
public static void main(String[] args)
{ try { int i = System.in.read(); if(i == '0')
throw new J_Exception(); //手动抛出异常
System.out.print("1");
}catch(IOException ex) {
System.out.print("2");
}catch(J_Exception ex) {
System.out.print("3");
}finally
{ System.out.println("4");
}
}
}
为什么当输入0时得到34