SCJP Quiz | OCJP Quiz | OCJP Online Test Series 1 | Java Online Test

class Super {
private int a;
protected Super(int a) { this.a = a; }
}

class Sub extends Super {
public Sub(int a) { super(a); }
public Sub() { this.a=5; }
}

Which one, independently, will allow Sub to compile?

Given:
7. void waitForSignal() {
8. Object obj = new Object();
9. synchronized (Thread.currentThread()) {
10. obj.wait();
11. obj.notify();
12. }
13. }
Which statement is true?

public class Rainbow {
public enum MyColor {
RED(0xff0000), GREEN(0x00ff00), BLUE(0x0000ff);
private final int rgb;
MyColor(int rgb) { this.rgb = rgb; }
public int getRGB() { return rgb; }
};
public static void main(String[] args) {
// insert code here
}
}
Which code fragment, inserted at line 19, allows the Rainbow class to compile?

public abstract class Shape {
private int x;
private int y;
public abstract void draw();
public void setAnchor(int x, int y) {
this.x = x;
this.y = y;
}
}

Which one class use the Shape class correctly?

public class Threads4 {
public static void main (String[] args) {
new Threads4().go();
}
public void go() {
Runnable r = new Runnable() {
public void run() {
System.out.print(“foo”);
}
};
Thread t = new Thread(r);
t.start();

}
}

public class Barn {
public static void main(String[] args) {
new Barn().go(“hi”, 1);
new Barn().go(“hi”, “world”, 2);
}
public void go(String… y, int x) {
System.out.print(y[y.length – 1] + ” “);
}
}

What is the result?

class PingPong2 {
synchronized void hit(long n) {
for(int i = 1; i

interface TestA { String toString(); }
public class Test {
public static void main(String[] args) {
System.out.println(new TestA() {
public String toString() { return “test”; }
});
}
}
What is the result?

1. public class Threads2 implements Runnable {
2.
3. public void run() {
4. System.out.println(“run.”);
5. throw new RuntimeException(“Problem”);
6. }
7. public static void main(String[] args) {
8. Thread t = new Thread(new Threads2());
9. t.start();
10. System.out.println(“End of method.”);
11. }
12. }
Which one can be result?

Given:
1. package test;
2.
3. class Target {
4. public String name = “hello”;
5. }

What can directly access and change the value of the variable name?

Which Man class properly represents the relationship “Man has a best friend
who is a Dog”?

class Nav{
public enum Direction { NORTH, SOUTH, EAST, WEST }
}
public class Sprite{
// insert code here
}

Which code, inserted at line 14, allows the Sprite class to compile?

class A{
public static void parse(String str) {
try {
float f = Float.parseFloat(str);
} catch (NumberFormatException nfe) {
f = 0;
} finally {
System.out.println(f);
}
}
public static void main(String[] args) {
parse(“invalid”);
}
}

What is the result?

class Mud {
public static void main(String…[] a) {// insert code here
System.out.println(“hi”);
}
}
And the following five fragments:
public static void main(String…a) {
public static void main(String.* a) {
public static void main(String… a) {
public static void main(String[]… a) {
public static void main(String…[] a) {
How many of the code fragments, inserted independently at line 12, compile?

class Atom {
Atom() { System.out.print(“atom “); }
}
class Rock extends Atom {
Rock(String type) { System.out.print(type); }
}
public class Mountain extends Rock {
Mountain() {
super(“granite “);
new Rock(“granite “);
}
public static void main(String[] a) { new Mountain(); }
}

What is the result?

class Building { }
public class Barn extends Building {
public static void main(String[] args) {
Building build1 = new Building();
Barn barn1 = new Barn();
Barn barn2 = (Barn) build1;
Object obj1 = (Object) build1;
String str1 = (String) build1;
Building build2 = (Building) barn1;
}
}

Which is true?

Given:
public void go() {
String o = “”;
z:
for(int x = 0; x

Which capability exists only in java.io.FileWriter?

Given that the current directory is empty, and that the user has read and write permissions, and
the following:
import java.io.*;
public class DOS {
public static void main(String[] args) {
File dir = new File(“dir”);
dir.mkdir();
File f1 = new File(dir, “f1.txt”);
try {
f1.createNewFile();
} catch (IOException e) { ; }
File newDir = new File(“newDir”);
dir.renameTo(newDir);
}
}

Which statement is true?

Assuming that the serializeBanana() and the deserializeBanana() methods will correctly use Java
serialization and given:

import java.io.*;
class Food implements Serializable {int good = 3;}
class Fruit extends Food {int juice = 5;}
public class Banana extends Fruit {
int yellow = 4;
public static void main(String [] args) {
Banana b = new Banana(); Banana b2 = new Banana();
b.serializeBanana(b); // assume correct serialization
b2 = b.deserializeBanana(); // assume correct
System.out.println(“restore “+b2.yellow+ b2.juice+b2.good);
}
// more Banana methods go here
}

What is the result?