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 < 3; i++) System.out.print(n + "-" + i + " "); } } public class Tester implements Runnable { static PingPong2 pp2 = new PingPong2(); public static void main(String[] args) { new Thread(new Tester()).start(); new Thread(new Tester()).start(); } public void run() { pp2.hit(Thread.currentThread().getId()); } } Which statement is true?

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 < 3; x++) { for(int y = 0; y < 2; y++) { if(x==1) break; if(x==2 && y==1) break z; o = o + x + y; } } System.out.println(o); } What is the result when the go() method is invoked?

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?