Java String length:
String length() is used to get the length of a Java String. The string length method returns the number of characters in String. The length is equal to the number of 16-bit Unicode characters in the string.
Syntax:
The signature of the String length() method is given below.public int length()
This method returns int value for characters in string.
String length example 1:
In this example, will see a basic example program to demonstrate length method. First call length method and prints it's length.
package examples.java.w3schools.string;
public class StringLengthExample {
public static void main(String[] args) {
String input1 = "java-w3schools";
int length1 = input1.length();
System.out.println("Input String length1: " + length1);
String input2 = "string length method";
int length2 = input2.length();
System.out.println("Input String length2: " + length2);
String input3 = "";
int length3 = input3.length();
System.out.println("Input String length3: " + length3);
}
}
Output:
Input String length1: 14
Input String length2: 20
Input String length3: 0
String length example 2:
Checking the pin code is valid or not. In India, Valid pin code length should be 6 digit number. Below code to check the length is valid or not.
package examples.java.w3schools.string;
public class StringLengthExample {
public static void main(String[] args) {
String pincode1 = "500001";
if (pincode1.length() == 6) {
System.out.println("given pincode " + pincode1 + " is valid");
} else {
System.out.println("given pincode " + pincode1 + " is not valid");
}
String pincode2 = "50000";
if (pincode2.length() == 6) {
System.out.println("given pincode " + pincode2 + " is valid");
} else {
System.out.println("given pincode " + pincode2 + " is not valid");
}
}
}
Output:
given pincode 500001 is valid
given pincode 50000 is not valid
Internal Implementation:
public int length() {
return value.length >> coder();
}
Here value is the byte array which is declared in String class as below.
@Stable
private final byte[] value;
The value is used for character storage.
This field is trusted by the VM, and is a subject to constant folding if String instance is constant. Overwriting this field after construction will cause problems.
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