Java Gets String Length

In Java, the java.lang.String class provides a method called length() that returns the length of a string. The length of a string is the number of characters it contains. In this tutorial, we will learn how to use the length() method to get the length of a string in Java.

Using the length() method:

To get the length of a string, simply call the length() method on the string object. The method returns an integer representing the number of characters in the string.

Example:

public class Main {
    public static void main(String[] args) {
        String str = "Hello, World!";
        int length = str.length();
        System.out.println("Length of the string: " + length);
    }
}

Output:

Length of the string: 13

Getting the length of a string with Unicode characters:

It is important to note that the length() method returns the number of 16-bit Unicode characters in the string. If the string contains Unicode characters that require more than 16 bits, the length() method will return a higher value than the actual number of visible characters.

To accurately count the number of Unicode code points in a string, you can use the codePointCount() method from the Character class.

Example:

public class Main {
    public static void main(String[] args) {
        String str = "Hello, 𐐷orld!";
        int length = str.length();
        int codePointCount = str.codePointCount(0, str.length());
        System.out.println("Length of the string: " + length);
        System.out.println("Number of Unicode code points: " + codePointCount);
    }
}

Output:

Length of the string: 14
Number of Unicode code points: 13

In this example, the Unicode character '𐐷' requires more than 16 bits, so the length() method returns a value that is greater than the number of visible characters in the string. The codePointCount() method, on the other hand, returns the correct number of Unicode code points.

In conclusion, the length() method in Java is used to get the length of a string, which represents the number of characters it contains. For strings with Unicode characters that require more than 16 bits, use the codePointCount() method to accurately count the number of Unicode code points.

Using length() method for strings in Java: The length() method in Java is used to find the length of a string.
```
String str = "Hello, Java!";
int length = str.length();
```
Calculating character count in a string in Java: To count the number of occurrences of a specific character in a string, you can iterate through the string and check each character.
```
String str = "Hello, Java!";
char targetChar = 'a';
int count = 0;

for (char c : str.toCharArray()) {
    if (c == targetChar) {
        count++;
    }
}
```
Getting byte length of a string in Java: To get the byte length of a string, you can use the getBytes() method.
```
String str = "Hello, Java!";
int byteLength = str.getBytes().length;
```
Counting words in a string in Java: You can count the number of words in a string by splitting it into an array of words using whitespace as a delimiter.
```
String str = "Hello Java Programming";
String[] words = str.split("\\s+");
int wordCount = words.length;
```
Handling null strings and length in Java: Before using the length() method, it's crucial to check if the string is not null to avoid NullPointerException.
```
String str = null;
int length = (str != null) ? str.length() : 0;
```
Using StringUtils for string length in Java: The Apache Commons Lang library provides StringUtils class, which has a length() method to handle null strings.
```
String str = null;
int length = StringUtils.length(str);
```
Java string length validation techniques: To validate the length of a string, you can use conditional statements or external libraries. For example, to check if a string has a length between 5 and 10 characters:
```
String str = "Hello";
if (str.length() >= 5 && str.length() <= 10) {
    // Valid length
} else {
    // Invalid length
}
```

Comparing string lengths in Java: String lengths can be compared using relational operators like <, <=, >, and >=.

String str1 = "Hello";
String str2 = "Java";
if (str1.length() > str2.length()) {
    // str1 is longer than str2
} else {
    // str2 is longer than or equal to str1
}