Java: parse int value from a char

Parsing numbers from hieroglyphs

If you're playing with non-Latin numerals, this is where Character.getNumericValue() starts moonwalking:

char hieroglyph = '६'; // Sanskrit numerals used before Excel was invented
int number = Character.getNumericValue(hieroglyph); // Result: 6, surprisingly
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Sans Excel, but ensures your app speaks Universal Cuneiform.

Handling surprise elements - non-numeric characters

While parsing integers from characters is like a walk in the park, meeting a non-numeric character could feel like stumbling upon a bear. It's betchar to check first with Character.isDigit():

char grizzly = '@';
if(Character.isDigit(grizzly)) {
    int run = grizzly - '0'; // Good luck outrunning this bear
} else {
    // Run away like the wind
}
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This quick check ensures the bear's more scared of you than you are of it.

Catch them all - parsing numbers from entire strings

It's not Pokemon, but here's how to catch every digit from a string and add them:

String forest = "b1e2a3r4s"; // Someone spelled bear using numbers, clever!
int honey = 0; // Start without any honey

// Catch all the numbers (honey) using a Pokeball (loop)
for (int i = 0; i < forest.length(); i++) {
    if (Character.isDigit(forest.charAt(i))) {
        honey += forest.charAt(i) - '0'; // Every caught number is made honey
    }
}
// Result: honey = 10, that's a lot of honey! 
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With a single Pokeball, you catch all the numbers and make honey out of them. Original bear is nowhere in sight!

ASCII - When speed is key

Life in the fast lane with ASCII characters and the - '0' trick:

int sum = 0;
for(char ch : charArray) {
    if('0' <= ch && ch <= '9') {
        sum += ch - '0'; // Adding to the stash like a speedy squirrel
    }
}
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This condition checks for numeric ASCII characters, faster than Sonic the Hedgehog, without needing extra method calls.

Alpha to Hexa - Parsing strings in different bases

Let's get hexy with numbers in hexadecimal or other bases:

String hex = "D"; // Not hexed, just hexadecimal
int decimal = Integer.parseInt(hex, 16); // Result: decimal = 13, hexed to normal
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With Integer.parseInt(String, int radix) you can be a magician and convert a string representation of a number in any base to a decimal form. Abracadabra!

Just remember to pull a NumberFormatException out of your magician's hat for any invalid input.