250+ TOP MCQs on Searching & Modifying a String and Answers [2024]

Java MCQs on searching and modifying a string of Java Programming Language.

1. Which of this method of class String is used to extract a substring from a String object?
a) substring()
b) Substring()
c) SubString()
d) None of the mentioned

Answer: a
Clarification: None.

2. What will s2 contain after following lines of Java code?

 String s1 = "one";
String s2 = s1.concat("two")

a) one
b) two
c) onetwo
d) twoone

Answer: c
Clarification: Two strings can be concatenated by using concat() method.

3. Which of these method of class String is used to remove leading and trailing whitespaces?
a) startsWith()
b) trim()
c) Trim()
d) doTrim()

Answer: b
Clarification: None.

4. What is the value returned by function compareTo() if the invoking string is greater than the string compared?
a) zero
b) value less than zero
c) value greater than zero
d) none of the mentioned

Answer: c
Clarification:

 if (s1 == s2) then 0, if(s1 &gt; s2) &gt; 0, if (s1 &lt; s2) then &lt; 0.

5. Which of the following statement is correct?
a) replace() method replaces all occurrences of one character in invoking string with another character
b) replace() method replaces only first occurrences of a character in invoking string with another character
c) replace() method replaces all the characters in invoking string with another character
d) replace() replace() method replaces last occurrence of a character in invoking string with another character

Answer: a
Clarification: replace() method replaces all occurrences of one character in invoking string with another character.

6. What will be the output of the following Java program?

```
    class output 
```
```
    {
```

        public static void main(String args[])

```
        { 
```

           String c = "  Hello World  ";

```
           String s = c.trim();
```

           System.out.println("""+s+""");

```
        }
```
```
    }
```

a) “”Hello World””
b) “”Hello World”
c) “Hello World”
d) Hello world

Answer: c
Clarification: trim() method is used to remove leading and trailing whitespaces in a string.
Output:

$ javac output.java
$ java output
"Hello World"

7. What will be the output of the following Java program?

```
    class output 
```
```
    {
```

        public static void main(String args[])

```
        { 
```
```
           String s1 = "one";
```
```
           String s2 = s1 + " two";
```
```
           System.out.println(s2);
```
```
        }
```
```
    }
```

a) one
b) two
c) one two
d) compilation error

Answer: c
Clarification: None.
Output:

$ javac output.java
$ java output
one two

8. What will be the output of the following Java program?

```
    class output 
```
```
    {
```

        public static void main(String args[])

```
        { 
```
```
           String s1 = "Hello";
```

           String s2 = s1.replace('l','w');

```
           System.out.println(s2);
```
```
        }
```
```
    }
```

a) hello
b) helwo
c) hewlo
d) hewwo

Answer: d
Clarification: replace() method replaces all occurrences of one character in invoking string with another character. s1.replace(‘l’,’w’) replaces every occurrence of ‘l’ in hello by ‘w’, giving hewwo.
Output:

$ javac output.java
$ java output
hewwo

9. What will be the output of the following Java program?

```
    class output 
```
```
    {
```

        public static void main(String args[])

```
        {
```
```
           String s1 = "Hello World";
```

           String s2 = s1.substring(0 , 4);

```
           System.out.println(s2);
```
```
        }
```
```
   }
```

a) Hell
b) Hello
c) Worl
d) World

Answer: a
Clarification: substring(0,4) returns the character from 0 th position to 3 rd position.
output:

$ javac output.java
$ java output 
Hell

10. What will be the output of the following Java program?

```
    class output 
```
```
    {
```

        public static void main(String args[])

        {             String s = "Hello World";

```
             int i = s.indexOf('o');
```

             int j = s.lastIndexOf('l');

             System.out.print(i + " " + j);

```
 
```
```
        }
```
```
   }
```

a) 4 8
b) 5 9
c) 4 9
d) 5 8

Answer: c
Clarification: indexOf() method returns the index of first occurrence of the character where as lastIndexOf() returns the index of last occurrence of the character.
output:

$ javac output.java
$ java output  
4 9

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