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Using a Variable or Array Element That Is Uninitialized and Unassigned

When we are using uninitialized variables or unassigned variables then we must know about what type of variable or what type of array we we are dealing with primitive or objects .because that time we can get diff behavior. but the java gives us a option of initializing a declared variable or leaving it uninitialized. And our behavior also depend on the variable  or level at which we are declaring our variable.right now we have a two variable which are using right now .

  1. Instance variable
  2. Local variable

Instance variable is basically declared with in the class but outside any method or constructor. But in the case of Local variable its declared with in the method or in the argument list of the method.
        

More interview questions and answers

Which of these classes are defined in java.io and used for file handling are abstract.

What result comes when we compile and run following code: public class R4RSCJPTest { public static void main(String args[]) { String str1="abcd"; String str2="efgh"; String str3=str1.concat(str2); str1.concat(str2); System.out.println(str1); } }

What result comes when we compile and run following code: public class Test { public static void main(String args[]) { String str1="abcd"; String str2="efgh"; String str3=str1.concat(str2); str1 = str1.concat(str2); System.out.println(str1); } }

What result comes when we compile and run following code: public class Test { public static void main(String args[]) { String str1="abcd"; String str2="efgh"; String str3=str1.concat(str2); str1 = str1.concat(str2); System.out.println(str1); } }

What result comes when we compile and run following code: public class Test { public static void main(String args[]) { String str1="abcd"; String str2="efgh"; String str3=str1.concat(str2); str1 = str1.concat(str2); System.out.println(str1); } }

Literals and Ranges of All Primitive Data Types

Range of Primitive Types

Literal Values for All Primitive Types

Integer Literals

Decimal Literals

Octal Literals

Hexadecimal Literals

Floating-Point Literals

Boolean Literals

Character Literals

Literal Values for Strings

Which primitive type would be best to represent the number of stars in the universe? A) long B) char C) char [] D) int

Which primitive type would be best to represent a single multiple choice question on a test, with only one answer allowed? A) float B) int C) char [] D) char

Which primitive type would be best to represent a single multiple choice question on a test, with more than one answer allowed? A) char B) long C) char [] D) int

Which primitive type would be best to represent the population of the U.S. in 2003? A) int (or long ) B) float (or double) C) char D) long

Which primitive type would be best to represent the amount of money (in dollars and cents) you plan on having at retirement? A) char B) long C) int (or long) D) float (or double)

Array

Choose correct collection interface which we use to represent stored elements into in particular sequence order.

Declaring an Array

Constructing an Array

Select correct method which is defined in Object class and can also used to convert an Integer Object into primitive int type.

Which are the legal identifiers from below.Select three correct options.

Select correct width (in bits) of double primitive type in Java.

What result comes when we compile and run following code: public class R4RSCJPTest { public static void main(String args[]) { int x = 15, y; if(x < 15) y = 3; if(x>= 15) y = 4; System.out.println("Value of y is " + y); } }

Initializing an Array

What result comes when we compile and run following code: class R4RSCJPTest { int i; int j; String str; public static void main(String args[]) { R4RSCJPTest test = new R4RSCJPTest(); System.out.println("String is " + test.str + " " + test.i + " " + test.j); } }

Select three correct options related to Java programming language.

What result comes when we compile and run following code: class R4RSCJPTest { public static void main() { System.out.println("Welcome"); } }

Select correct options which is use to declare main method.

Initializing Elements in a Loop

Declaring, Constructing, and Initializing on One Line

What result comes when we compile and run following code: public class R4RSCJPTest { public static void main(String args[]) { int x, y; int z = 4; z++; y = 3; y++; z = y = z = 2; System.out.println("Value of z is = "+z ); } }

Constructing and Initializing an Anonymous Array

Arrays of Primitives

Arrays of Object References

What result comes when we compile and run following code: public class R4RSCJPTest { public static void main(String args[]) { int x, y; int z = 4; z++; y = 4; y++; z+= y-= x = 2; if( z == 6) z-= 3; else z+= 3; System.out.println("Value of z is "+z ); } }

Array Reference Assignments for One-Dimensional Arrays

Array Reference Assignments for Multidimensional Arrays

Using a Variable or Array Element That Is Uninitialized and Unassigned

What result comes when we compile and run following code: public class R4RSCJPTest { int i = 1; public static void main(String args[]) { int i = 2; i = new_i(i); System.out.println("New value of i is " +i); } public static int new_i(int i) { i = 3; i *= 4; return i; } }

What result comes when we compile and run following code: public class R4RSCJPTest { int i = 1; public static void main(String args[]) { int i = 2; new_i(i); System.out.println("New value of i is " +i); } public static void new_i(int i) { i = 3; i *= 4; } }

What result comes when we compile and run following code: public class R4RSCJPTest { int i[] = {0}; public static void main(String args[]) { int i[] = {1}; new_i(i); System.out.println("New value of i[0] is " +i[0]); } public static void new_i(int i[]) { i[0] = 2; i[0] *= 3; } }

What result comes when we compile and run(with command line argument R4R welcome in intellegence world. in following code: public class R4RSCJPTest { public static void main(String args[]) { System.out.println(args[0]+" "+args [args.length-1]); } }

What result comes when we compile and run(with command line argument like: R4R welcomes you in intelligence world) following code: public class test { public static void main(String args[]) { System.out.println(args[0]+" "+args.length); } }

What result comes when we compile and run following code: class R4RSCJPTest { public static void main(String args[]) { int i,j,k,l=0; k = l++; j = ++k; i = --j; System.out.println("Value of i is " +i); } }

What result comes when we compile and run following code: public class R4RSCJPTest { public static void main(String args[]) { char c; int i; c = 'A'; //1 i = c; //2 c = i + 1; //3 i++; //4 } }

Select correct signed of left shift operator.

What result comes when we compile and run following code: public class R4RSCJPTest { public static void main(String args[]) { int i = 1; boolean t = true; boolean f = false, boo; boo = (t && ((i++) == 0)); boo = (f && ((i+=2) > 0)); System.out.println("Value of i is " +i); } }

What result comes when we compile and run following code: public class R4RSCJPTest { public static void main(String args[]) { int i = 1; boolean t = true; boolean f = false, boo; boo = (t & ((i++) == 0)); boo = (f & ((i+=2) > 0)); System.out.println("Value of i is " +i); } }

Primitive Instance Variables

Object Reference Instance Variables

Array Instance Variables

Local Primitives

Local Objects

Local Arrays

Command-Line Arguments to Main

Declarations and Modifiers

Class Declarations and Modifiers

Class Access

Default Access

Public Access

Other (Nonaccess) Class Modifiers

Final Classes

Abstract Classes

Creating an Abstract Superclass and Concrete Subclass

Method and Variable Declarations and Modifiers.

Member Access

Public Members

Private Members

Local Variables and Access Modifiers

Nonaccess Member Modifiers

Final Methods

Final Arguments

What result comes when we compile and following code: public class R4RSCJPTest { public static void main(String args[]) { byte i = 4; i = (byte)~i; System.out.println("Value of i is " +i); } }

Select operator which we use in Java for bitwise inversion.

What result comes when we compile and run following code: public class R4RSCJPTest { public static void main(String args[]) { int i,j; i = 1 & 5; j = 2 | 7; System.out.println("Value of i is " + i + ", Value of j is " + j ); } }

What result comes when we compile and run following code: public class R4RSCJPTest { public static void main(String args[]) { int i = -1; int j = i>>3; int k = j & 129; System.out.println("Value of k is " +k); } }

What result comes when we compile and run following code: public class R4RSCJPTest { public static void main(String args[]) { int i,j; i = 1 | 5 ; j = 2 ^ 7; System.out.println("Value of i is " + i + ", Value of j is " + j); } }

Synchronized Methods

Native Methods

Strictfp Methods

What result comes when we compile and run following code: public class R4RSCJPTest { public static void main(String args[]) { boolean boo = true; int i; if(boo) i = boo ? 3: 2; else i = boo ? 4: 1; System.out.println("Value of i is " +i); } }

What result comes when we compile and run following code: public class R4RSCJPTest { public static void main(String args[]) { boolean boo = false; int i; if(boo) i = boo ? 3: 2; else i = boo ? 4: 1; System.out.println("Value of i is " +i); } }

What result comes when we compile and run following code: public class R4RSCJPTest { public static void main(String args[]) { int i = 0; if(i < 0) i = 1; switch(i) { case 2: System.out.println(2); case 0: System.out.println(0); case 1: System.out.println(1); break; case 3: System.out.println(3); default: System.out.println(4); break; } } }

What result comes when we compile and run following code: public class R4RSCJPTest { public static void main(String args[]) { int i, j; i = 7 >> 2; j = 7 >>> 2; System.out.println("Value of i is " +i+",Value of j is " +j); } }

What result comes when we compile and run following code: public class R4RSCJPTest { public static void main(String args[]) { int i; i = -2 << 1; i = i >> 3; i = i >>> 2; System.out.println("Value of i is " +i); } }

What result comes when we compile and run following code: public class R4RSCJPTest { public static void main(String args[]) { int i; i = -2 << 1; i = i >>> 2; i = i >> 1; System.out.println("Value of i is " +i); } }

What result comes when we compile and run following code: public class R4RSCJPTest { public static void main(String args[]) { int i = -4; i = i << 2; System.out.println("Value of i is " +i); } }

Select correct signed right shift operator from following.

Select shift operator which are not used in Java.

What result comes when we compile and run following code: public class R4RSCJPTest { public static void main(String args[]) { int i = 0, J = 1, k; if(i) k = 2; else k = 1; if(j) k = 0; else k = 3; System.out.println("Value of k is " +k); } }

What result comes when we compile and run following code: public class R4RSCJPTest { public static void main(String args[]) { for(int i = 0; i < 2; i++) { for(int j = 1; j >= 0; j--) { if(i == j) continue; System.out.println("Value of i is "+ i + ", Value of j is " + j); } } } }

What result comes when we compile and run following code: public class Test { public static void main(String args[]) { for(int i = 0; i < 2; i++) { for(int j = 1; j >= 0; j--) { if(i == j) break; System.out.println("Value of i is "+ i + ", Value of j is " + j); } } } }

What result comes when we compile and run following code: public class R4RSCJPTest { public static void main(String args[]) { outer: for(int i = 0; i < 2; i++) { for(int j = 2; j >= 0; j--) { if(i == j) continue outer; System.out.println("Value of i is " +i+ ", Value of j is " +j); } } } }

What result comes when we compile and run following code: public class R4RSCJPTest { public static void main(String args[]) { outer: for(int i = 0; i < 2; i++) { for(int j = 2; j >= 0; j--) { if(i == j) break outer; System.out.println("Value of i is " +i+ ", Value of j is " +j); } } } }

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