In this article, we will discuss how to get length of StringBuilder object using StringBuilder’s length() method
1. StringBuilder’s length() method :
- This StringBuilder method is used to get length of StringBuilder or character count
- That’s sequence of characters or number of characters appended/inserted into StringBuilder
1.1 Method Signature:
public int length();
1.2 Returns:
- Returns length i.e.; character count
2. Examples on length() method :
Generally, length() method of StringBuilder class is used for following purpose,
- To get length or character count
- for-loop – used to keep boundary condition, while iterating
- while-loop – used to keep boundary condition, while iterating
- do–while-loop – used to keep boundary condition, while iterating
- To create equivalent char[] array
Let’s see examples for each listed above cases:
2.1 To get length or character count of StringBuilder :
StringBuilderLengthMethod.java
package in.bench.resources.stringbuilder.methods;
public class StringBuilderLengthMethod {
public static void main(String[] args) {
// StringBuilder object
StringBuilder sbUrl = new StringBuilder("Google.com");
// to check length of the StringBuilder
int length = sbUrl.length();
// print to console
System.out.println("The length of StringBuilder '"
+ sbUrl + "' is " + length);
}
}
Output:
The length of StringBuilder 'Google.com' is 10
2.2 Boundary condition for for-loop while iterating :
StringBuilderLengthForLoop.java
package in.bench.resources.stringbuilder.methods;
public class StringBuilderLengthForLoop {
public static void main(String[] args) {
// StringBuilder object
StringBuilder sbUrl = new StringBuilder("Oracle.com");
// iterating using for-loop
for(int index = 0; index < sbUrl.length(); index++) {
System.out.println("StringBuilder character at "
+ index + "-position is : "
+ sbUrl.charAt(index));
}
}
}
Output:
StringBuilder character at 0-position is : O
StringBuilder character at 1-position is : r
StringBuilder character at 2-position is : a
StringBuilder character at 3-position is : c
StringBuilder character at 4-position is : l
StringBuilder character at 5-position is : e
StringBuilder character at 6-position is : .
StringBuilder character at 7-position is : c
StringBuilder character at 8-position is : o
StringBuilder character at 9-position is : m
2.3 Boundary condition for while-loop while iterating
StringBuilderLengthWhileLoop.javac
package in.bench.resources.stringbuilder.methods;
public class StringBuilderLengthWhileLoop {
public static void main(String[] args) {
// StringBuilder object
StringBuilder sbUrl = new StringBuilder("Amazon.com");
// initialize index
int index = 0;
// get length
int length = sbUrl.length();
// iterating using while-loop
while(index < length){
// print to console
System.out.println("StringBuilder character at "
+ index + "-position is : "
+ sbUrl.charAt(index));
// increment index-value by 1
index++;
}
}
}
Output:
StringBuilder character at 0-position is : A
StringBuilder character at 1-position is : m
StringBuilder character at 2-position is : a
StringBuilder character at 3-position is : z
StringBuilder character at 4-position is : o
StringBuilder character at 5-position is : n
StringBuilder character at 6-position is : .
StringBuilder character at 7-position is : c
StringBuilder character at 8-position is : o
StringBuilder character at 9-position is : m
2.4 Boundary condition for do-while-loop while iterating
StringBuilderLengthDoWhileLoop.java
package in.bench.resources.stringbuilder.methods;
public class StringBuilderLengthDoWhileLoop {
public static void main(String[] args) {
// StringBuilder object
StringBuilder sbUrl = new StringBuilder("Apple.com");
// initialize index
int index = 0;
// get length
int length = sbUrl.length();
// iterating using do-while-loop
do {
// print to console
System.out.println("StringBuilder character at "
+ index + "-position is : "
+ sbUrl.charAt(index));
// increment index-value by 1
index++;
} while(index < length);
}
}
Output:
StringBuilder character at 0-position is : A
StringBuilder character at 1-position is : p
StringBuilder character at 2-position is : p
StringBuilder character at 3-position is : l
StringBuilder character at 4-position is : e
StringBuilder character at 5-position is : .
StringBuilder character at 6-position is : c
StringBuilder character at 7-position is : o
StringBuilder character at 8-position is : m
Q) Difference between while-loop and do-while-loop:
- do-while-loop checks boundary condition, after 1st loop iteration (at least 1 iteration is possible)
- while-loop checks boundary condition even before 1st iteration (no iteration is possible without satisfying loop-entry condition)
2.5 To create equivalent char[] array
StringBuilderLengthCreateCharArray.java
package in.bench.resources.stringbuilder.methods;
public class StringBuilderLengthCreateCharArray {
public static void main(String[] args) {
// StringBuilder object
StringBuilder sbUrl = new StringBuilder(
"BenchResources.Net");
// get length
int length = sbUrl.length();
// create character array object
char[] chArray = new char[length];
// iterate using for-loop & store into char[] array
for (int index = 0; index < length ; index++) {
// store into char[] array
chArray[index] = sbUrl.charAt(index);
}
// print to console - this is demo purpose
System.out.println("The converted char[] array is : "
+ String.valueOf(chArray));
}
}
Output:
The converted char[] array is : BenchResources.Net
Related Articles :
- Java – StringBuilder class
- Java – StringBuilder append() method (13)
- Java – StringBuilder capacity() method
- Java – StringBuilder charAt(int index) method
- Java – StringBuilder delete(int start, int end) method
- Java – StringBuilder deleteCharAt(int index) method
- Java – StringBuilder ensureCapacity(int minimumCapacity) method
- Java – StringBuilder indexOf() method (2)
- Java – StringBuilder insert() method (12)
- Java – StringBuilder lastIndexOf() method (2)
- Java – StringBuilder length() method
- Java – StringBuilder replace(int start, int end, String str) method
- Java – StringBuilder reverse() method
- Java – StringBuilder substring(int start, int end) method
References :
- https://docs.oracle.com/javase/8/docs/api/java/lang/String.html
- https://docs.oracle.com/javase/8/docs/api/java/lang/class-use/String.html
- https://docs.oracle.com/javase/8/docs/api/java/lang/StringBuffer.html
- https://docs.oracle.com/javase/8/docs/api/java/lang/StringBuilder.html
Happy Coding !!
Happy Learning !!
