In the previous part, Java Interview Questions and Answers Part I and Java Interview Coding problems for Freshers- Part II, we have explained some basic questions of Java. This part is in continuation with the previous Java Interview Questions and Answers tutorial. In this part of the tutorial we will proceed with more questions based on further concepts of Java.

21 - Write a program to concatenate string using for Loop

/*Example:

Input 5

Output - 1 2 3 4 5 */

class Join{ 
public static void main(String args[]){ 
int num = Integer.parseInt(args[0]); 
String result = " "; 
for(int i=1;i<=num;i++){ 
result = result + i + " "; 
} 
System.out.println(result); 
} 
} 

Output of the program would be when argument passes is 10

/*
1 2 3 4 5 6 7 8 9 10
*/

22 - Program to Display Multiplication Table

class MultiplicationTable{ 
public static void main(String args[]){ 
int num = Integer.parseInt(args[0]); 
System.out.println("*****MULTIPLICATION TABLE*****"); 
for(int i=1;i<=num;i++){ 
for(int j=1;j<=num;j++){ 
System.out.print(" "+i*j+" "); 
} 
System.out.print("\n"); 
} 
} 
} 

/*
*****MULTIPLICATION TABLE*****
1  2  3  4  5
2  4  6  8  10
3  6  9  12  15
4  8  12  16  20
*/

Program 23 - Write a program to Swap the values

class Swap{ 
public static void main(String args[]){ 
int num1 = Integer.parseInt(args[0]); 
int num2 = Integer.parseInt(args[1]); 
System.out.println("\n***Before Swapping***"); 
System.out.println("Number 1 : "+num1); 
System.out.println("Number 2 : "+num2); 
//Swap logic 
num1 = num1 + num2; 
num2 = num1 - num2; 
num1 = num1 - num2; 
System.out.println("\n***After Swapping***"); 
System.out.println("Number 1 : "+num1); 
System.out.println("Number 2 : "+num2); 
} 
} 

Output of the program would be when num1=10 and num2=5

/*
***Before Swapping***
Number 1 : 10
Number 2 : 5

***After Swapping***
Number 1 : 5
Number 2 : 10

*/

24 - Write a program to convert given no. of days into months and days.(Assume that each month is of 30 days)

/*Example :

Input 69

Output - 69 days = 2 Month and 9 days */

class DayMonthDemo{ 
public static void main(String args[]){ 
int num = Integer.parseInt(args[0]); 
int days = num%30; 
int month = num/30; 
System.out.println(num+" days = "+month+" Month and "+days+" days"); 
} 
} 

Output of the program would be when argument passed is 66

/*
66 days = 2 Month and 6 days
*/

25 - Write a program to find whether given no. is Armstrong or not.

/*Example :

Input 153

Output - 1^3 + 5^3 + 3^3 = 153, so it is Armstrong no. */

class Armstrong{ 
public static void main(String args[]){ 
int num = Integer.parseInt(args[0]); 
int n = num; //use to check at last time 
int check=0,remainder; 
while(num > 0){ 
remainder = num % 10; 
check = check + (int)Math.pow(remainder,3); 
num = num / 10; 
} 
if(check == n) 
System.out.println(n+" is an Armstrong Number"); 
else 
System.out.println(n+" is not a Armstrong Number"); 
} 
} 

Output of the Armstrong program would be

/*
sh-4.3$ javac Armstrong.java
sh-4.3$ java-Xmx128M-Xms16M  Armstrong
10 is not a Armstrong Number
sh-4.3$ javac Armstrong .java
sh-4.3$ java -Xmx128M -Xms16M  Armstrong
153 is an Armstrong Number
*/

26 - Switch case demo

/*Example : Input - 124 Output - One Two Four */

class SwitchCaseDemo{ 
public static void main(String args[]){ 
try{ 
int num = Integer.parseInt(args[0]); 
int n = num; //used at last time check 
int reverse=0,remainder; 
while(num > 0){ 
remainder = num % 10; 
reverse = reverse * 10 + remainder; 
num = num / 10; 
} 
String result=""; //contains the actual output 
while(reverse > 0){ 
remainder = reverse % 10; 
reverse = reverse / 10; 
switch(remainder){ 
case 0 : 
result = result + "Zero "; 
break; 
case 1 : 
result = result + "One "; 
break; 
case 2 : 
result = result + "Two "; 
break; 
case 3 : 
result = result + "Three "; 
break; 
case 4 : 
result = result + "Four "; 
break; 
case 5 : 
result = result + "Five "; 
break; 
case 6 : 
result = result + "Six "; 
break; 
case 7 : 
result = result + "Seven "; 
break; 
case 8 : 
result = result + "Eight "; 
break; 
case 9 : 
result = result + "Nine "; 
break; 
default: 
result=""; 
} 
} 
System.out.println(result); 
}catch(Exception e){ 
System.out.println("Invalid Number Format"); 
} 
} 
} 

Output of the Switch case program would be when argument passed is 7896

/*
Seven Eight Nine Six
*/