Cracking Java String class questions

1. Give the output of the following:

1. 1. System.out.println (“Simply”. charAt(1));
   2. String na = “Simply Coding”;
      System.out.println( na . length( ) );
   3. System.out.println( “SiMPly”.indexOf(“M”));
   4. System.out.println(“SiMPly”.equalsIgnoreCase(“simply”));

Ans.

1. 1. i
   2. 13
   3. 2
   4. True

2. What is the output of the following program?  

public class check
{
public static void change(String nm)
{
nm = “Simply”;
}
public static void main()
{
String name = “Coding”;
System.out.println(name);
change(name);
System.out.println(name);
}
}

Ans

Coding
Coding

3. What is the output of the following statements when executed?

public class Mathtest
{
public static void change(char [] nm)
{
nm[1] = 'S';
}
public static void main (String args[])
{
char name[] = {'a', 'b'};
System.out.println(name[1]);
change(name);
System.out.println(name[1]);
}
}

Ans

b
S

4. What is the output of the following statements when executed?

char ch[ ]= {‘I’ 'N', ‘T', ‘E', 'L', ‘P', ‘E’, ‘N', ‘T’, ‘I’, ‘U', 'M'};
String obj= new String(ch, 3, 4);
System.out.println("The result is = "+ obj );

Ans.:

The result is = ELPE

5. State the output of this program Segment?

String str1 = ”Simply”;
String str2= “Coding”;
System.out.println(str1.substring(0,2). concat(str2.substring(1)));
System.out.println(( “WH”+(str1.substring(2).toUpperCase() )));

Ans.

The 1st output is= Sioding
( because str1. Substring(0,2)gives “Si” & str2. Substring(1) gives “oding”)

The 2nd output is= WHMPLY
( because str1. Substring(2). toUpperCase() gives “MPLY”, so ”WH”+” MPLY”= “WHMPLY”)

6. If String n1 = “89”; and String n2=”100”; Give the output of the following:

1. 1. String st= n1+n2; System.out.println (st) ;
   2. System.out.println( n1.charAt( 1 ));
   3. System.out.println( n2 + n1);
   4. System.out.println(n1+ “ ”+n2);

Ans.

1. 1. 89100
   2. 9
   3. 10089
   4. 89 100

7. Give the output of following program.

class MainString{
public static void main(String args [ ])
{
StringBuffer s = new Stringbuffer(“Simply”);
if( (s.length()>5) && (s.append(“Coding”). equals(“X”)) ); //empty statement
System.out.println(s);
}
}

Ans.

SimplyCoding

8. What is the output of this code

String st = " SimplyCoding";
int len= st.length();
for(int j= len-1; j>= 0 ; j-- )
System.out.print( st.charAt(j) );

Ans. gnidoCylpmiS

9. Assume a string “Delhi” is assigned in a variable st and “Singapore” is assigned in variable na. Write a small code to interchange values of st and na.

Ans.

String temp= st;
st= na;
па= temp;

10. If String x = “SimplyCoding”;
     String y= “Programs”;

What do the following functions return for:

1. 1. System.out.printin( x. substring( 1, 7));
   2. System.out.println (x. indexOf( x.charAt( 6)));
   3. System.out.println (y +x. substring( 5));
   4. System.out.println( x.equals( y));

Ans.

1. 1. implyCo ( extracts substring from st to 6th index, 1 means 1st index and 6 means 6th index as array starts with 0)
   2. 6
   3. ProgramsyCoding
   4. False

11. Write valid java statements to perform the following operations on strings.

1. 1. Extract 10 characters from the 1st character to 10th character in string address to a new string str.
   2. To print the position of the first occurrence of the letter ‘R’ in the string city

Ans.

1. 1. String str = address.substring( 0, 10 );
   2. System.out.println( “The position =” + city. indexOf (‘R’));

12. What will be the output of the following program, when Method invoke() is called:

public class StringArray
{
void change(String arr[])
{
for(int i=0;i<arr.length;i++)
{
arr[i]=arr[i].substring(0,1).toUpperCase()+arr[i].substring(1);
}
}
void invoke()
{
String ar[]={“simply”,“coding”,“programs”};
for(int i=0;i<ar.length;i++)
System.out.println(ar[i]);
change(ar);
for(int i=0;i<ar.length;i++)
System.out.println(ar[i]);
}
}

Ans.

simply
coding
programs
Simply
Coding
Programs

13. Give the output of the following program fragment:

String s=new String("Hello! this is simply coding");
String t;
t=s.replace("this is","Welcome to");
System.out.println(t);

Ans.

Hello! Welcome to simply coding

14. Give the output of the following program fragment:

String s="india",s1="SimPLY",s2=s;
System.out.println(s.equals(s1));
System.out.println(s.equalsIgnoreCase(s1));
System.out.println(s2==s);
System.out.println(s.toUpperCase()==s1.toUpperCase());
System.out.println(s.startsWith("IM".toLowerCase()));
System.out.println(s1.endsWith("iA".toUpperCase()));

Ans.

false
false
true
false
false
false

15. What do the following functions return for:

String x ="Simply";
String y ="Coding";
System.out.println(x + y);
System.out.println(x.length());
System.out.println(x.charAt(3));
System.out.println(x.equals(y));

Ans.

SimplyCoding
6
p
false

16. What is the output of the following:

(i)    System.out.println ("output1 :" + 6 + 4);
       System.out.println ("output2 :"+(6+4));

(ii) String S1 = "Hi";
     String S2 = "Hi";
     String S3 = "Simply";
     String S4 = "HI";
     System.out.println(S1 + "equals" + S2 + "→" + S1.equals(S2));
     System.out.println(S1 + "equals" + S3 + "→" + S1.equals(S3));
     System.out.println(S1 + "equals" + S4 + "→" + S1.equals(S4));
     System.out.println(S1 + "equalsIgnoreCase" +S4 + "→" + S1.equalsIgnoreCase(S4));

Ans.

(i) output1 :64
     output2 :10

(ii)  HiequalsHi→true

      HiequalsSimply→false

      HiequalsHI→false

     HiequalsIgnoreCaseHI→true

17. If, String x = “Simply”;
    String y = “Coding”;

1. 1. System.out.println(x.substring(1,4));
   2. System.out.println(x.indexOf(x.charAt(4)));
   3. System.out.println(y+x.substring(5));
   4. System.out.println(x.equals(y));

Ans.

1. 1. imp
   2. 4
   3. Codingy
   4. False

18. Write a statement each to perform the following task on a string:

(i) Find and display the position of the last space in a string s.
(ii) Convert a number stored in a string variable x to double data type

Ans.

(i) System.out.println(s.lastIndexOf(“ ”));
(ii) double d=Double.parseDouble(x);

19. Write a statement each to perform the following task on a string:

(i) Extract the second last character of a word stored in the variable wd.
(ii) Check if the second character of a string str is in uppercase.

Ans.

(i) char sl=wd.charAt(wd.length()-2);
(ii) if(Character.isUpperCase(str.charAt(1)))

20. Give the output of the following string functions:

1. 1. “SimplyCoding”.replace(‘i’,’A’)
   2. “Eating”.compareTo(“Coding”)

Ans.

1. 1. SAmplyCodAng
   2. 2

21. Consider the following String array and give the output:

String arr[]={"Java","PHP","Python",".Net","HTML"};
System.out.println(arr[0].length()>arr[3].length());
System.out.print(arr[2].substring(0,3));

Ans.

false
Pyt

22. String x[]={“Simply”,”Coding”,”Online”,”Tutor”,”Courses”};
    Give the output of the following statements:

(i) System.out.println(x[1]);
(ii) System.out.println(x[3].length());

Ans.

(i) Coding
(ii) 5

23. Write the output for the following:

String s="Simply Coding";
System.out.println(s.indexOf('T'));
System.out.println("Welcome to"+" "+s.substring(0,10));

Ans.

-1
Welcome to Simply Cod

24. Write a statement each to perform the following task on a string:

          String s1 = “good”, s2 = “going”;
          1 . Write coed to concat them into string s.
          2 . Write coed to replace ‘g’ with ‘f’ in string s

Ans.  s = s1.concat(s2)
          s = s.replace(‘g’, f)

24. Give the ouput of the following string functions:

(i) “SimplyCoding”.indexOf(‘l’)+”SimplyCoding”.lastIndexOf(‘C’)
(ii) “Simply”.compareTo(“SimplyCoding”)

Ans.

(i) 10
(ii) -6

25. State the output of the following program segment when executed:

String a = "Simply", b = "Coding";
String h = a.substring(1, 3);
String k = b.substring(2).toUpperCase();
System.out.println(h);
System.out.println(k.equalsIgnoreCase(h));

Ans.

im
false

26. State the output of the following program segment:

String str1 = "Simply", str2 = "Coding";
System.out.println(str1.substring(0,2).concat(str2.substring(1)));
System.out.println(("HL" + (str1.substring(2).toUpperCase())));

Ans.

Sioding
HLMPLY

27. State the value of characteristic and mantissa when the following code is executed.

String s = "6.2708";
int n = s.indexOf('.');
int characteristic = Integer.parseInt(s.substring(0,n));
int mantissa = Integer.valueOf(s.substring(n+1));

Ans.

characteristic=6
mantissa= 2708

28. State the output of the following program segment.

String s = "SimplyCoding";
int n = s.length();
System.out.println(s.startsWith(s.substring(4, n)));
System.out.println(s.charAt(1) == s.charAt(9));

Ans.

false
true

29. What will the following code output?

String s = "SimplyCoding";
System.out.println(s.indexOf('i'));
System.out.println(s.lastIndexOf('i'));

Ans.

1
9

30. Give the output of the following:
    

String str1 = "replace";
str1.toUpperCase();
System.out.println(str1);

Ans. replace

30. Give the output of the following:

String s1 = "Simply";
String s2 = "Coding";
System.out.println(s1.substring (0,3).concat(s2.substring(4)));
System.out.println(s1.endsWith("e"));

Ans.

Simng
False