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| Learn Java programming through these flash cards. |
1. Given a package named EDU.Student, how would you import a class named Test contained in this package? Write one line statement.
Answer: import EDU.Student.Test;
2. Consider the following class definition:
class Student
{
abstract double result( )
}
This code will not compile since a keyword is missing in the first line. What is the keyword?
Answer: abstract
3. Consider the following class file:
import java.awt.*;
import java.io.*;
package studentBase;
class Test
{
void display( )
{
System.out.println("RESULTS");
}
}
Will it compile? Yes or No. Give reason, if No.
Answer: No; The package definition must come first.
4. Consider the following code:
class Product
{
public static void main(String args[ ])
{
int x = 10, y = 20;
System.out.println(mul(x, y));
}
int mul(int a, int b)
{
return(a * b);
}
}
Will it compile? Yes or No. Give reason, if No.
Answer: No; The static method is trying to invoke a non-static method.
5. Given below are two files:
File Employee.java
package purchase
public class Employee
{
protected double age = 35.00;
}
File Company.java
import purchase.Employee;
public class Company
{
public static void main(String arg[ ])
{
Employee e = new Employee( );
System.out.println("Age =" + e.age);
}
}
Will it compile? Yes or No. Give reason, if No.
Answer: No; The field age in the Employee class should be public.
6. Consider the following code:
class A
{
void method(int x)
{ System.out.println("x =" + x); }
}
class B extends A
{
void method(int y)
{ System.out.println("y =" + y); }
void method(String s)
{ System.out.println("s =" + s); }
public static void main(String args[ ])
{
A a1 = new A( );
A a2 = new B( );
a1.method(10);
a2.method(20);
}
}
What will be the output, when executed?
Answer: x = 10; y = 20
7. There are three classes that implement the DataInput and DataOutput interfaces. Two of them are DataInputStream and DataOutputStream. Which is the third one?
Answer: RandomAccessFile class
8. What output will the following program produce?
class Bits
{
public static void main(String args[ ])
{
short s1 = 3; // 0000 0011
short s2 = 13; // 0000 1101
s1 = (short) (s1 ^ s2);
System.out.println("Result is " + s1);
}
}
Answer: Result is 14
9. State the output of the following program:
class Condition
{
public static void main(String args[ ])
{
int x = 10;
int y = 15;
System.out.println((x
}
}
Answer: Result = 3.0
10. Which of the classes in java.io package defines a method to delete a file?
Answer: File class
11. Given a valid File object reference, we can create a new file using two classes defined in java.io package. One is FileOutputStream class. Which is the other one?
Answer: RandomAccessFile class
12. If raf is an instance of RandomAccessFile, how can we move the file pointer to the end of the file? Write the statement.
Answer: raf.seek(raf.length(();
13. What will be the output of the following program when it is executed with the command line
java Command Java is wonderful
class Command
{
public static void main(String args[ ])
{
for(int i = 1; i < args.length; i++)
{
System.out.print(args[i]);
if( i != args.length )
System.out.print(" ");
}
System.out.println(" ");
}
}
Answer: is wonderful
14. What will be the output of the following code snippet when combined with suitable declarations and run?
StringBuffer city = new StringBuffer("Madras");
StringBuffer string = new StringBuffer( );
string.append(new String(city));
string.insert(0, "Central ");
String.out.println(string);
Answer: Central Madras
15. Consider the following program code:
class Thread1 extends Thread
{
public void run( )
{
System.out.println("Begin");
suspend( );
resume( );
System.out.println("End");
}
} class ThreadTest
{
public static void main(String args[ ])
{
Thread T1 = new Thread1( );
T1.start( );
}
}
On execution, what will be the output?
Answer: Begin
Try the Quiz : Java Programming : Flash Cards II
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