String Builder

Why String Builder?

public class StringBuild {  	public static void main( String[] args ){  		String str1 = "Hi";  		String str2 = "There";  		String str3 = str1 + ", " +str2 + "!";    	}  }

• The above code introduces 3 different string objects.
• This leads to unnecessary memory consumption due to the multiple object creation.
• At such point you should use StringBuilder

• public class StringBuild {  	public static void main( String[] args ){  		String str1 = "Hi";  		String str2 = "There";  		String str3 = str1 + ", " +str2 + "!";    		StringBuilder sb = new StringBuilder("Hi");  		sb.append(", ");  		sb.append("There");  		sb.append("!");    		System.out.println(sb);    	}  }

  Output: Hi, There!

• This way there is only one object creation.
• Here, the append returns a reference to the StringBuilder object.
• Code Optimization:
  

  		StringBuilder sb = new StringBuilder("Hi")  		.append(", ")  		.append("There")  		.append("!");

   

Using Scanner

import java.util.Scanner;  public class StringBuild {  	public static void main( String[] args ){  		String str1 = "Hi";  		String str2 = "There";  		String str3 = str1 + ", " +str2 + "!";    		StringBuilder sb = new StringBuilder("Hi")  		.append(", ")  		.append("There")  		.append("!");    		System.out.println(sb);    		Scanner sn = new Scanner(System.in);  		System.out.println("Enter a String");  		String ip = sn.nextLine();  //nextLine waits for user to type in something and press enter    		System.out.println(ip);    	}  }

 

Using StringBuilder and Scanner

import java.util.Scanner;  public class StringBuild {  	public static void main( String[] args ){  		String str1 = "Hi";  		String str2 = "There";  		String str3 = str1 + ", " +str2 + "!";    		StringBuilder sb = new StringBuilder("Hi")  		.append(", ")  		.append("There")  		.append("!");    		System.out.println(sb);    		Scanner sn = new Scanner(System.in);  		System.out.println("Enter a String");  		String ip = sn.nextLine();  //nextLine waits for user to type in something and press enter    		System.out.println(ip);    		//First deleting contents of sb.  		sb.delete(0, sb.length()); //delete(starting position, ending position)    		for(int i = 0; i < 3; i++) {  			ip = sn.nextLine();  			sb.append(ip + "\n");  		}    		System.out.println(sb);    	}  }

Output

• Hi, There!
• Enter a String
• A value
• A value
• Hello
• World
• !
• Hello
• World
• !