Java String Max Size

In Java, a string is internally stored as an array of characters. This means the max size of a string is equal to the max size of an array, which is Integer.MAX_VALUE (or 2^31 – 1) = 2147483647. However, in practice, the actual maximum size of a String is limited by the available memory on the system.

Although, you are unlikely to face any issues as the number 2147483647 is huge, however in case, if you are dealing with such huge amount of data then it is better to switch to a different data structure or file based storage rather than consuming the whole memory of system.

Program to print max length of String

Let’s say, If you want to write a Java program to find the max length of a string that contains only char ‘a’. Note: Running this program might consume a large amount of memory and could potentially crash your JVM if the available memory is insufficient. Use caution when running it, especially on systems with limited memory.

public class MaxStringSize {
    public static void main(String[] args) {
        // Try to create a String with the maximum size
        try {
            int maxSize = Integer.MAX_VALUE;
            StringBuilder builder = new StringBuilder(maxSize);
            for (int i = 0; i < maxSize; i++) {
                builder.append('a'); // filling the string with 'a' chars
            }
            String maxString = builder.toString();
            System.out.println("String created successfully with size: " + maxString.length());
        } catch (OutOfMemoryError e) {
            System.err.println("Failed to create string. Out of memory.");
            e.printStackTrace();
        }
    }
}

In this program, we attempt to create a string with the max size possible in Java. We are using StringBuilder to create a string by appending ‘characters’a’ repeatedly until it reaches the maximum size. If the program runs out of memory during this process, the program catches it using OutOfMemoryError exception and prints the error message.