Java Programmer Certification Mock Exam

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Question 1

Which of these methods modify the contents of the String instance on which it is invoked?

Question 2

class SRC106 {
  public static void main(String[] args) {
    double d1 = Math.floor(0.5);
    double d2 = Math.floor(1.5);
    System.out.print(d1 + "," + d2);
}}

What is the result of attempting to compile and run the program?

Question 3

class MWC204 {
  static void m1(StringBuffer s1) {
    s1 = s1.append("B"); System.out.print(s1);
  }
  static void m2(StringBuffer s1) {
    s1.append("C"); System.out.print(s1);
  }
  public static void main(String[] s) {
    StringBuffer s1 = new StringBuffer("A");
    m1(s1); m2(s1);
    System.out.print(s1);
}}

What is the result of attempting to compile and run the program?

Question 4

class E {
  public static void main (String[] args) {
    Byte b1 = new Byte("1"), b2 = new Byte("1");
    int a = b1.hashCode(), b = b2.hashCode();
    System.out.print((b1.equals(b2))+","+(a==b));
}}

What is the result of attempting to compile and run the program?

Question 5

class E {
  static String m(int i) {return "int primitive";}
  static String m(Integer i) {return "Integer instance";}
  static String m(double i) {return "double primitive";}
  static String m(Double i) {return "Double instance";}
  static String m(String i) {return "String instance";}
  public static void main (String[] args) {
    System.out.print(m(Integer.parseInt("1")));
}}

What is the result of attempting to compile and run the program?

Question 6

class F {
  static String m(long i) {return "long";}
  static String m(Long i) {return "Long";}
  static String m(double i) {return "double";}
  static String m(Double i) {return "Double";}
  static String m(String i) {return "String";}
  public static void main (String[] args) {
    System.out.print(m(Long.parseLong("1L")));
}}

What is the result of attempting to compile and run the program?

Question 7

Which of the following methods are static members of the java.lang.Double class?

Question 8

class E {
  static String m(float f) {return "f";}
  static String m(Float f) {return "F";}
  public static void main (String[] args) {
    System.out.print(m(Float.parseFloat("1")));
    System.out.print(m(Float.floatValue()));
    System.out.print(m(Float.valueOf("1")));
}}

What is the result of attempting to compile and run the program?

Question 9

class D {
  public static void main (String[] args) {
    Boolean b1 = Boolean.valueOf("trUE");           // 1
    Boolean b2 = Boolean.valueOf("Even more true"); // 2
    Boolean b3 = Boolean.valueOf(null);             // 3
    System.out.print((b1==b2) + ",");
    System.out.print((b2==b3) + ",");
    System.out.println(b3==b1);
}}

What is the result of attempting to compile and run the program?

Question 10

class E {
  static String m(short s) {return "p";}
  static String m(Short s) {return "S";}
  public static void main (String[] args) {
    Short s1 = new Short("1");
    System.out.print(m(s1.shortValue())+",");
    System.out.print(m(Short.parseShort("1"))+",");
    System.out.print(m(Short.valueOf("1")));
}}

What is the result of attempting to compile and run the program?

Question 11

Which of these methods is a static member of the java.lang.String class?

Question 12

class SRC107 {
  public static void main (String[] args) {
    int a = -1; long b = -2;
    float c = -3.0f; double d = -4.0;
    a = Math.abs(a); b = Math.abs(b);
    c = Math.abs(c); d = Math.abs(d);
    System.out.print(a+b+c+d);
}}

What is the result of attempting to compile and run the program?

Question 13

class MWC205 {
  static void m1(StringBuffer s1) {
    s1.append("B"); System.out.print(s1);
  }
  static void m2(StringBuffer s1) {
    s1 = new StringBuffer("C"); System.out.print(s1);
  }
  public static void main(String[] s) {
    StringBuffer s1 = new StringBuffer("A");
    m1(s1); m2(s1);
    System.out.print(s1);
}}

What is the result of attempting to compile and run the program?

Question 14

class F {
  public static void main (String[] args) {
    System.out.print(Byte.MIN_VALUE+","+Byte.MAX_VALUE);
}}

What is the result of attempting to compile and run the program?

Question 15

class D {
  public static void main (String args[]) {
    boolean b1 = Integer.MIN_VALUE == 0x80000000;
    boolean b2 = Integer.MAX_VALUE == 0x7FFFFFFF;
    System.out.print(b1 + "," + b2);
}}

What is the result of attempting to compile and run the program?

Question 16

class G {
  public static void main (String[] args) {
    Long l1 = new Long("1"), l2 = new Long("1");
    int h1 = l1.hashCode(), h2 = l2.hashCode();
    StringBuffer s1 = new StringBuffer("1");
    StringBuffer s2 = new StringBuffer("1");
    int h3 = s1.hashCode(), h4 = s2.hashCode();
    System.out.print((l1.equals(l2) & (h1==h2)) + ",");
    System.out.print(s1.equals(s2) | (h3==h4));
}}

What is the result of attempting to compile and run the program?

Question 17

Which methods of the java.lang.Double class return a primitive value?

Question 18

class F {
  static String m(float f) {return "f";}
  static String m(Float f) {return "F";}
  public static void main (String[] args) {
    Float f1 = new Float(1);
    System.out.print(m(f1.parseFloat("1")));
    System.out.print(m(f1.floatValue()));
    System.out.print(m(f1.valueOf("1")));
}}

What is the result of attempting to compile and run the program?

Question 19

class E {
  static String m1(boolean b) {return "b";}
  static String m1(Boolean b) {return "B";}
  public static void main(String[] args) {
    Boolean b1 = new Boolean(true);
    System.out.print(m1(Boolean.valueOf(null)));
    System.out.print(m1(b1.booleanValue()));
    System.out.println(m1(Boolean.TRUE));
}}

What is the result of attempting to compile and run the program?

Question 20

class MWC106 {
  static void m1(String s) {
    s = s.trim(); s = s.concat("D");
  }
  public static void main(String[] s) {
    String s1 = "A", s2 = " B ", s3 = "C";
    m1(s2);
    System.out.print(s1 + s2 + s3);
}}

What is the result of attempting to compile and run the program?