Java implements a simple character generator code example

Creates a successful string object whose length is fixed and whose content cannot be modified or edited. While "+" can be used to add new characters or strings, "+" generates a new String instance and creates a new String object in memory. If you make changes to the string repeatedly, you will greatly increase the overhead. J2SE adds the variable character sequence string-builder class from 5.0, greatly increasing the efficiency of adding strings frequently. Let's look at a simple example.

public class Jerque { 
 
   
  public static void main(String[] args) { 
    // TODO Auto-generated method stub 
    String str = ""; 
    long startTime1 = System.currentTimeMillis(); 
    for (int i =0; i<10000; i++) 
    { 
      str = str +i;   
    } 
    long endTime1 = System.currentTimeMillis(); 
    long time1 = endTime1 - startTime1; 
    System.out.println(" string 1 Elapsed time :"+ time1); 
     
    StringBuilder builder = new StringBuilder(""); 
    long startTime2 = System.currentTimeMillis(); 
    for (int i=0;i<10000;i++) 
    { 
      builder.append(i); 
    }   
    long endTime2 = System.currentTimeMillis(); 
    long time2 = endTime2 - startTime2; 
    System.out.println(" string 2 Elapsed time :" + time2); 
  } 
} 

String 1 elapsed time :1210& PI;
String 2 consumes time :3& PI;

Conclusion:

1. The String-Builder class, which comes with JAVA, undoubtedly greatly improves the efficiency.  
2. The usual methods of doing this are : 
A. Append (content) method  
B. Insert (int offset,arg) method & offset;
    StringBuilder b = new StringBuilder("Hello");  
    B.i nsert (5, "World!" );  
    System. The out. Println (b.t ostring ());  
C. Delete (int start,int end) method  
    StringBuilder d = new StringBuilder("StringBuilder");  
    D.d elete (5, 10);  
    System. The out. Println (" which oString () ");