Output of Java Programs | Set 50

Q 1. What is the output of this program? 

Java

// Class
class Example {
    private int x;

    // Main driver method
    public static void main(String args[])
    {
        Example obj = new Example(5);
    }
    public Example(int x)
    {
        System.out.println("x = " + x);
    }

    public void Example(int x) { System.out.println(x); }
}

Option 
A. 0 
B. Garbage value 
C. Compile time error : variable is not initialized 
D. Run time error : a is the blank variable 

Output:

C. Compile time error : variable is not initialized

Explanation: In Java, final variable becomes 0 by default. Only three ways to initialize the final variable 1. using constructor 2. initialization block 3. At the time of variable declaration.

Q 2: What is the output of this program?

Java

class Test {

    // Main driver method
    public static void main(String args[])
    {
        // Input strings
        String str1 = new String("Hello World");
        String str2 = new String("Hello World");

        String str3 = "Hello World";
        String str4 = "Hello World";

        int a = 0, b = 0, c = 0;

        if (str3 == str4)
            a = 1;
        else
            a = 2;

        if (str1.equals(str3))
            b = 1;
        else
            b = 2;

        if (str1 == str4)
            c = 1;
        else
            c = 2;

        // Printing values in variables
        System.out.println("a= " + a + " b= " + b
                           + " c= " + c);
    }
}

Option

A. 0 
B. Garbage value 
C. Compile time error 
D. No output: Blank Screen 

Output:

D. No output : Blank Screen

Explanation: There are no constructors in this program. This is a method just like name of the class but it is not a constructor because the constructor does not return type. So in this program output is a blank screen. 

Q 3: What is the output of this program? 

Option

A. x = 5 
B. 5 
C. Compile time error: ambiguous call of Example(int) 
D. Run time error 

Output:

A. x = 5

Explanation: In this program “public Example(int)” is the constructor and “public void Example(int)” is the method so the compiler will not be confused. And constructor will be automatically called at the time of object creation. 

Q 4: What is the output of this program? 

Java

class Test {

    // Main driver method
    public static void main(String args[])
    {
        // Input strings
        String str1 = new String("Hello World");
        String str2 = new String("Hello World");

        String str3 = "Hello World";
        String str4 = "Hello World";

        int a = 0, b = 0, c = 0;

        if (str3 == str4)
            a = 1;
        else
            a = 2;

        if (str1.equals(str3))
            b = 1;
        else
            b = 2;

        if (str1 == str4)
            c = 1;
        else
            c = 2;

        // Printing values in variables
        System.out.println("a= " + a + " b= " + b
                           + " c= " + c);
    }
}

Option:

A. a=2 b=1 c=2 
B. a=2 b=2 c=2 
C. a=1 b=2 c=1 
D. a=1 b=1 c=2 

Output:

D. a=1 b=1 c=2

Explanation: When we make the object with the help of new keyword then a new memory created and reference variable contain the memory location. Here two times memory is created with same string but we are comparing objects not string, so object are pointing to different memory locations so they are not equal.

Q 5. How many objects created in the above example?

Option:

A. 1 
B. 2 
C. 3 
D. 4 

Output:

B.2