1..请说出E类中标注的【代码1】~【代码4】的输出结果。 import java.io. *; public class E{ public static void main(String args ]){ int n= - 1; File f = new File( " hello.txt"); byte]a= "abcd" . getBytes(); try{ FileOutputStream out = new FileOutputStream(f); out.write(a); out.close(); FileInputStream in = new FileInputStream(f); byte] tom= new byte 3]; int m= in. read(tom, 0,3); System. out. println(m);//【代码1】 String s = new String(tom, 0, 3); System. out. println(s); //代码2】 m= in.read(tom, 0, 3); System. out. println(m);//代码3】 s = new String( tom, 0,3); System. out. println(s);//【代码4】 catch( IOException e){} } } 

输出结果： 3 abc 1 abc