Java StringBuilder append() Method

Java StringBuilder append() Method | In this blog, we will discuss the append() method given in the StringBuilder class. There are many variations of the append method of the StringBuilder class. The append() method is used to append the StringBuilder to primitives, strings, objects, and character sequences.

The different variations of the append() method are:-

1. public StringBuilder append(Object obj)
2. public StringBuilder append(String str)
3. public StringBuilder append(StringBuffer sb)
4. public StringBuilder append(CharSequence s)
5. public StringBuilder append(CharSequence s, int start, int end)
6. public StringBuilder append(char[ ] str)
7. public StringBuilder append(char[ ] str, int offset, int len)
8. public StringBuilder append(boolean b)
9. public StringBuilder append(char c)
10. public StringBuilder append(int i)
11. public StringBuilder append(long lng)
12. public StringBuilder append(float f)
13. public StringBuilder append(double d)

StringBuilder Append Java Example

Let us see an example of the StringBuilder class append() method by appending different type of values like int, float, double, String, and e.t.c.

public class Main {
   public static void main(String[] args) {
      StringBuilder sb = new StringBuilder("");
      sb.append("Hello");
      sb.append(20);
      sb.append('K');
      sb.append(true);
      sb.append(50.90);
      System.out.println(sb);
   }
}

Output:-

Hello20Ktrue50.9

In the below program we are using StringBuilder append(boolean bool) variations, the syntax for this method is as follows: public StringBuilder append(boolean bool)

public class Main {
   public static void main(String[] args) {
      StringBuilder sb = new StringBuilder("Are you ready? ");
      System.out.println("Before appending: " + sb);
      sb.append(true);
      System.out.println("After appending: " + sb);

      StringBuilder sb1 = new StringBuilder("Are you ok? ");
      System.out.println("Before appending: " + sb1);
      sb1.append(false);
      System.out.println("After appending: " + sb1);
   }
}

Output:-

Before appending: Are you ready?
After appending: Are you ready? true
Before appending: Are you ok?
After appending: Are you ok? false

Example of StringBuilder Java Append

Let us see a program to append a character to the StringBuilder object. The method syntax to append the character is:- public StringBuilder append(char ch)

public class Main {
   public static void main(String[] args) {
      StringBuilder sb = new StringBuilder("Welcome Boy");
      System.out.println(sb);
      sb.append('s');
      System.out.println("After appending = " + sb);

      sb = new StringBuilder("Hello world");
      System.out.println(sb);
      sb.append('#');
      System.out.println("After appending = " + sb);
   }
}

Output:-

Welcome Boy
After appending = Welcome Boys
Hello world
After appending = Hello world#

We can also append an array to StringBuilder. The append() method syntax for it is:- public StringBuilder append(char[ ] charray)

public class Main {
   public static void main(String[] args) {

      StringBuilder sb = new StringBuilder("We are ");
      System.out.println(sb);
      char[] array = { 'P', 'R', 'O', 'G', 'R', 'A', 'M', 'M', 'E', 'R', 'S' };
      sb.append(array);
      System.out.println("After appending = " + sb);

      sb = new StringBuilder("Let us say together - ");
      System.out.println(sb);
      array = new char[] { 'a', 'b', 'c', 'd', 'e', 'f', 'g' };
      sb.append(array);
      System.out.println("After appending = " + sb);
   }
}

Output:-

We are
After appending = We are PROGRAMMERS
Let us say together –
After appending = Let us say together – abcdefg

The StringBuilder class also contains public StringBuilder append(char[ ] str, int offset, int len) which can be used to append only some portion of the char array.

public class Main {
   public static void main(String[] args) {
      StringBuilder sb = new StringBuilder("Java ");
      System.out.println("String Builder = " + sb);
      char[] array = { 'P', 'r', 'o', 'g', 'r', 'a', 'm', 'm', 'i', 'n', 'g' };
      sb.append(array, 0, 7);
      System.out.println("After appending StringBuilder = " + sb);
   }
}

Output:-

String Builder = Java
After appending StringBuilder = Java Program

If you enjoyed this post, share it with your friends. Do you want to share more information about the topic discussed above or do you find anything incorrect? Let us know in the comments. Thank you!

Search