Java How to Convert String to Boolean - Simple Guide

In Java, convert a string to boolean using Boolean.parseBoolean(yourString), which returns true if the string equals "true" ignoring case, otherwise false.

Examples

Input"true"

Outputtrue

Input"False"

Outputfalse

Input"hello"

Outputfalse

How to Think About It

To convert a string to a boolean, check if the string exactly matches "true" ignoring case. If yes, return true; otherwise, return false. This approach treats any other string as false.

Algorithm

1

Get the input string.

2

Compare the string to "true" ignoring case.

3

If it matches, return true.

4

Otherwise, return false.

Code

java

public class StringToBoolean {
    public static void main(String[] args) {
        String input = "True";
        boolean result = Boolean.parseBoolean(input);
        System.out.println(result);
    }
}

Output

true

Dry Run

Let's trace converting the string "True" to boolean.

1

Input string

input = "True"

2

Parse string to boolean

Boolean.parseBoolean("True") returns true

3

Print result

Output: true

Input String	Boolean.parseBoolean Result
True	true

Why This Works

Step 1: Parsing logic

The Boolean.parseBoolean() method checks if the input string equals "true" ignoring case.

Step 2: Return value

If the string matches "true", it returns true; otherwise, it returns false.

Alternative Approaches

Using Boolean.valueOf()

java

public class StringToBoolean {
    public static void main(String[] args) {
        String input = "true";
        Boolean result = Boolean.valueOf(input);
        System.out.println(result);
    }
}

Returns a Boolean object instead of primitive boolean; useful if you need an object.

Manual comparison

java

public class StringToBoolean {
    public static void main(String[] args) {
        String input = "true";
        boolean result = "true".equalsIgnoreCase(input);
        System.out.println(result);
    }
}

Manually compares string ignoring case; same result but more explicit.

Complexity: O(n) time, O(1) space

Time Complexity

The method compares the input string to "true" ignoring case, which takes O(n) time where n is the string length.

Space Complexity

No extra space is used besides a few variables, so space complexity is O(1).

Which Approach is Fastest?

Boolean.parseBoolean() and manual comparison have similar performance; Boolean.valueOf() adds object creation overhead.

Approach	Time	Space	Best For
Boolean.parseBoolean()	O(n)	O(1)	Simple primitive boolean conversion
Boolean.valueOf()	O(n)	O(1)	When Boolean object needed
Manual equalsIgnoreCase	O(n)	O(1)	Explicit control over comparison