JAVA程序员笔试题目与答案

1. Given: Integer i = new Integer (42); Long l = new Long (42); Double d = new Double (42.0); Which two expressions evaluate to True? A. (i == 1) B. (i == d) C. (d == 1) D. (i.equals (l)) E. (d.equals (l)) F. (i.equals (42)) G. none of above Answer: 2. Given: public class Foo { public static void main (String [] args) { StringBuffer a = new StringBuffer("A"); StringBuffer b = new StringBuffer ("B"); operate (a,b); System.out.println(a + "," +b); } static void operate(StringBuffer x, StringBuffer y) { x.append(y); y = x; } } What is the result? A. The code compiles and prints “A,B”. B. The code compiles and prints “A,A”. C. The code compiles and prints “B,B”. D. The code compiles and prints “AB,B”. E. The code compiles and prints “AB,AB”. F. The code does not compile because “+” cannot be overloaded for StringBuffer. Answer: 3.Given: class BaseClass { private float x = 1.0f ; protected float getVar() {return x;} } class Subclass extends BaseClass { private float x = 2.0f; //insert here } Which two are valid examples of method overriding? A. float getVar() { return x;} B. public float getVar() { return x;} C. public double getVar() { return x;} D. protected float getVar() { return x;} E. public float getVar(float f) { return f;} Answer: 4. Which of the following are methods of the Runnable interface A) run B) start C) yield D) stop Answer: 5. Which of the following are legal statements? A) float f=1/3; B) int i=1/3; C) float f=1.01; D) double d=999d; Answer: 6. Given: public class test( public static void main(string[] args){ String foo = args[1]; String baz = args[2]; String bax = args[3]; } } And the command line invocation: Java Test red green blue What is...