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1. [20pts]

   Ex2.java	Ex3.java
   public class Ex2 { public static void main(String[] args) { String s; System.out.println(s.length()); } }	public class Ex3 { public static void main(String[] args) { String s = null; System.out.println(s.length()); } }
   Try compiling and running this. Do you get a compile-time or run-time error? What is the problem?	Try compiling and running this. Do you get a compile-time or run-time error? What is the problem?

2. [5pts] Why is it that String s = null; is OK, but double x = null; is not?
    
3. [75pts] Write a program HW02.java that reads in number n, followed by n strings, then prints out the strings columnwise (with spaces between column elements). A sample run looks like this:

   ~/$ java HW02
   4 hello goodbye destiny alive
   h g d a 
   e o e l 
   l o s i 
   l d t v 
   o b i e 
     y n   
     e y   

   Rules: you must define and use in your program a function public static int maxLength(String[] A) that takes an array of Strings as an argument and returns the length of the longest string. If I were you, I would define and thoroughly test this function before doing anything else!
   Hints: Here are a few helpful tidbits.
   • If A is an array, A.length gives the length/size/number-of-elements for A. Note that there are no ()s!
   • If s is a string, s.length() gives the length/size/number-of-characters for s. Note the ()'s!
   • System.out.println(...) prints its argument followed by a newline. System.out.print(...) does the same, but without sticking the newline at the end.
   • System.out.println(), i.e. calling println with no arguments, prints a newline and nothing else.
   • Recall that if s is a String, the character at index i in s is given by s.charAt(i).
   • java.lang.math (available with import java.lang.*) provides a max function. You call it like this: int i = Math.max(a,b);

1. a printout of this sheet (filled in)
2. a printout of your code using the codeprint button from the submit system: