OCJP Quiz | SCJP Quiz | OCJP Online Test Series 3 | Java Online Test

public class Test {
public static void main(String [] args) {
int x = 5;
boolean b1 = true;
boolean b2 = false;

if ((x == 4) && !b2 )
System.out.print(“1 “);
System.out.print(“2 “);
if ((b2 = true) && b1 )
System.out.print(“3 “);
}
}

What is the result?

package com.company.application;

public class MainClass {
public static void main(String[] args) {}
}

And MainClass exists in the /apps/com/company/application directory. Assume the CLASSPATH
environment variable is set to “.” (current directory).
Which one java command entered at the command line will run MainClass?

interface Foo {}
class Alpha implements Foo {}
class Beta extends Alpha {}
class Delta extends Beta {
public static void main( String[] args ) {
Beta x = new Beta();
// insert code here
}
}

Which code, inserted at line 16, will cause a java.lang.ClassCastException?

Which code, inserted at line 16, will cause a java.lang.ClassCastException?

public class LineUp {
public static void main(String[] args) {
double d = 12.345;
// insert code here
}
}

Which code fragment, inserted at line 4, produces the output | 12.345|?

Which one statements is true about the hashCode method?

A company has a business application that provides its users with many different reports: receivables reports, payables reports, revenue projects, and so on. The company has just purchased some new, state-of-the-art, wireless printers, and a programmer has been assigned the task of enhancing all of the reports to use not only the company’s old printers, but the new wireless printers as well. When the programmer starts looking into the application, the programmer discovers that because of the design of the application, it is necessary to make changes to each report to support the new printers. Which one design concepts most likely explain this situation?

public class Test {
public static void main(String [] args) {
for(int x = 1; x System.out.print(args[x] + ” “);
}
}
}

and two separate command line invocations:
java Yippee
java Yippee 1 2 3 4
What is the result?

A company that makes Computer Assisted Design (CAD) software has, within its application, some utility classes that are used to perform 3D rendering tasks. The company’s chief scientist has just improved the performance of one of the utility classes’ key rendering algorithms, and has assigned a programmer to replace the old algorithm with the new algorithm. When the programmer begins researching the utility classes, she is happy to discover that the algorithm to be replaced exists in only one class. The programmer reviews that class’s API, and replaces the old algorithm with the new algorithm, being careful that her changes adhere strictly to the class’s API. Once testing has begun, the programmer discovers that other classes that use the class she changed are no longer working properly. What design flaw is most likely the cause of these new bugs?

class Foo {
public int a = 3;
public void addFive() { a += 5; System.out.print(“f “); }
}
class Bar extends Foo {
public int a = 8;
public void addFive() { this.a += 5; System.out.print(“b ” ); }

public static void main(String args[]){
Foo f = new Bar();
f.addFive();
System.out.println(f.a);

}

}

What is the result?

Given a pre-generics implementation of a method:
public static int sum(List list) {
int sum = 0;
for ( Iterator iter = list.iterator(); iter.hasNext(); ) {
int i = ((Integer)iter.next()).intValue();
sum += i;
}
return sum;
}

Which one changes must be made to the method sum to use generics?

import java.util.*;
public class WrappedString {
private String s;
public WrappedString(String s) { this.s = s; }
public static void main(String[] args) {
HashSet

What is the result?

public class Tea {
public static void main(String [] args) {
int x = 5;
Tea t = new Tea();
t.doStuff(x);
System.out.print(” main x = ” + x);
}

void doStuff(int x) {
System.out.print(” doStuff x = ” + x++);
}
}

What is the result?

// insert code here
private N min, max;
public N getMin() { return min; }
public N getMax() { return max; }
public void add(N added) {
if (min == null || added.doubleValue() max.doubleValue())
max = added;
}
}
Which one, inserted at line 11, will allow the code to compile?

import java.util.*;
public class GetInLine {
public static void main(String[] args) {
PriorityQueue pq = new PriorityQueue();
pq.add(“banana”);
pq.add(“pear”);
pq.add(“apple”);
System.out.println(pq.poll() + ” ” + pq.peek());
}
}

What is the result?

class SuperCalc {
protected static int multiply(int a, int b) { return a * b;}
}

public class SubCalc extends SuperCalc{
public static int multiply(int a, int b) {
int c = super.multiply(a, b);
return c;
}

public static void main(String args[]){
SubCalc sc = new SubCalc ();
System.out.println(sc.multiply(3,4));
System.out.println(SubCalc.multiply(2,2));

}

}

What is the result?

class Thingy { Meter m = new Meter(); }
class Component { void go() { System.out.print(“c”); } }
class Meter extends Component { void go() { System.out.print(“m”); } }

class DeluxeThingy extends Thingy {
public static void main(String[] args) {
DeluxeThingy dt = new DeluxeThingy();
dt.m.go();
Thingy t = new DeluxeThingy();
t.m.go();
}
}

Which one is true?

import java.util.*;
public class Mapit {
public static void main(String[] args) {
Set set = new HashSet();
Integer i1 = 45;
Integer i2 = 46;
set.add(i1);
set.add(i1);
set.add(i2); System.out.print(set.size() + ” “);
set.remove(i1); System.out.print(set.size() + ” “);
i2 = 47;
set.remove(i2); System.out.print(set.size() + ” “);
}
}

What is the result?

class ClassA {
public int numberOfInstances;
protected ClassA(int numberOfInstances) {
this.numberOfInstances = numberOfInstances;
}
}
public class ExtendedA extends ClassA {
private ExtendedA(int numberOfInstances) {
super(numberOfInstances);
}
public static void main(String[] args) {
ExtendedA ext = new ExtendedA(420);
System.out.print(ext.numberOfInstances);
}
}

Which statement is true?

public class Bat {
int squares = 81;
public static void main(String[] args) {
new Bat().go();
}
void go() {
incr(++squares);
System.out.println(squares);
}
void incr(int squares) { squares += 10; }
}

What is the result?

interface Animal { void makeNoise(); }
class Horse implements Animal {
Long weight = 1200L;
public void makeNoise() { System.out.println(“whinny”); }
}
public class Icelandic extends Horse {
public void makeNoise() { System.out.println(“vinny”); }
public static void main(String[] args) {
Icelandic i1 = new Icelandic();
Icelandic i2 = new Icelandic();
Icelandic i3 = new Icelandic();
i3 = i1; i1 = i2; i2 = null; i3 = i1;
}
}

When line 14 is reached, how many objects are eligible for the garbage collector?