Add a Character to a String at a Given Position
The Kubernetes ecosystem is huge and quite complex, so it’s easy to forget about costs when trying out all of the exciting tools.
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Slow MySQL query performance is all too common. Of course it is. A good way to go is, naturally, a dedicated profiler that actually understands the ins and outs of MySQL.
The Jet Profiler was built for MySQL only, so it can do things like real-time query performance, focus on most used tables or most frequent queries, quickly identify performance issues and basically help you optimize your queries.
Critically, it has very minimal impact on your server’s performance, with most of the profiling work done separately — so it needs no server changes, agents or separate services.
Basically, you install the desktop application, connect to your MySQL server, hit the record button, and you’ll have results within minutes:
DbSchema is a super-flexible database designer, which can take you from designing the DB with your team all the way to safely deploying the schema.
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The Kubernetes ecosystem is huge and quite complex, so it’s easy to forget about costs when trying out all of the exciting tools.
To avoid overspending on your Kubernetes cluster, definitely have a look at the free K8s cost monitoring tool from the automation platform CAST AI. You can view your costs in real time, allocate them, calculate burn rates for projects, spot anomalies or spikes, and get insightful reports you can share with your team.
Connect your cluster and start monitoring your K8s costs right away:
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1. Introduction
In this quick tutorial, we’ll demonstrate how to add a character at any given position in a String in Java.
We’ll present three implementations of a simple function which takes the original String, a character and the position where we need to add it.
Since the String class is final and immutable the function should return a new String with the added character.
2. Using a Character Array
Here, the idea is to create a new character array and copy the characters from the original String before the given position.
After that, we put the new character at the position and copy the rest of the characters from the original String in the subsequent positions of the new array.
Finally, we construct the desired String from that array.
public String addChar(String str, char ch, int position)
Compared to the other two methods, this is a low-level design approach and gives us the most flexibility.
3. Using the substring Method
An easier and higher level approach is to use the substring() method of the String class. It prepares the String by concatenating:
- The substring of the original String before the position
- The new character
- The substring of the original String after the position
public String addChar(String str, char ch, int position)
Although the above code is more readable, it has a downside in that it creates a number of temporary objects to determine the result. As String is an immutable class, every call to its substring() method creates a new String instance.
Finally, when we concatenate the parts, the compiler creates a StringBuilder object for appending them one by one. Every String and StringBuilder object allocates separate memory locations for its internal character array.
This implementation also needs to copy all the characters thrice from one array to another.
If we need to call the method a huge number of times, the temporary objects may fill the heap memory and that will trigger GC very frequently. This can also affect the performance to some extent.
4. Using a StringBuilder
StringBuilder is a utility class provided by Java library to construct and manipulate String objects in a number of ways.
We can implement the same functionality using the insert() method of the StringBuilder class:
public String addChar(String str, char ch, int position)
The above code needs to create only a single StringBuilder object to insert the character at the position. It allocates the same amount of memory that the original String has, but to create a place for the new character the underlying array shifts the next characters by 1 position.
Although using a StringBuilder may be slower, it doesn’t have the memory burden of initializing temporary objects. We also end up with code that is simple and readable.
5. Conclusion
In this article, we focused on several ways of adding a character in a String object in Java. We’ve seen that the implementation using a character array offers the best performance and that with the substring method gives a more readable approach.
The preferred way of implementing the solution is using the StringBuilder class – as it’s simple, less bug-prone and offers good and stable performance.
As usual, the complete source code for the above tutorial is available over on GitHub.
Slow MySQL query performance is all too common. Of course it is. A good way to go is, naturally, a dedicated profiler that actually understands the ins and outs of MySQL.
The Jet Profiler was built for MySQL only, so it can do things like real-time query performance, focus on most used tables or most frequent queries, quickly identify performance issues and basically help you optimize your queries.
Critically, it has very minimal impact on your server’s performance, with most of the profiling work done separately — so it needs no server changes, agents or separate services.
Basically, you install the desktop application, connect to your MySQL server, hit the record button, and you’ll have results within minutes:
Class StringBuilder
A mutable sequence of characters. This class provides an API compatible with StringBuffer , but with no guarantee of synchronization. This class is designed for use as a drop-in replacement for StringBuffer in places where the string buffer was being used by a single thread (as is generally the case). Where possible, it is recommended that this class be used in preference to StringBuffer as it will be faster under most implementations.
The principal operations on a StringBuilder are the append and insert methods, which are overloaded so as to accept data of any type. Each effectively converts a given datum to a string and then appends or inserts the characters of that string to the string builder. The append method always adds these characters at the end of the builder; the insert method adds the characters at a specified point.
For example, if z refers to a string builder object whose current contents are » start «, then the method call z.append(«le») would cause the string builder to contain » startle «, whereas z.insert(4, «le») would alter the string builder to contain » starlet «.
In general, if sb refers to an instance of a StringBuilder , then sb.append(x) has the same effect as sb.insert(sb.length(), x) .
Every string builder has a capacity. As long as the length of the character sequence contained in the string builder does not exceed the capacity, it is not necessary to allocate a new internal buffer. If the internal buffer overflows, it is automatically made larger.
Instances of StringBuilder are not safe for use by multiple threads. If such synchronization is required then it is recommended that StringBuffer be used.
Unless otherwise noted, passing a null argument to a constructor or method in this class will cause a NullPointerException to be thrown.
Class StringBuilder
A mutable sequence of characters. This class provides an API compatible with StringBuffer , but with no guarantee of synchronization. This class is designed for use as a drop-in replacement for StringBuffer in places where the string buffer was being used by a single thread (as is generally the case). Where possible, it is recommended that this class be used in preference to StringBuffer as it will be faster under most implementations.
The principal operations on a StringBuilder are the append and insert methods, which are overloaded so as to accept data of any type. Each effectively converts a given datum to a string and then appends or inserts the characters of that string to the string builder. The append method always adds these characters at the end of the builder; the insert method adds the characters at a specified point.
For example, if z refers to a string builder object whose current contents are » start «, then the method call z.append(«le») would cause the string builder to contain » startle «, whereas z.insert(4, «le») would alter the string builder to contain » starlet «.
In general, if sb refers to an instance of a StringBuilder , then sb.append(x) has the same effect as sb.insert(sb.length(), x) .
Every string builder has a capacity. As long as the length of the character sequence contained in the string builder does not exceed the capacity, it is not necessary to allocate a new internal buffer. If the internal buffer overflows, it is automatically made larger.
Instances of StringBuilder are not safe for use by multiple threads. If such synchronization is required then it is recommended that StringBuffer be used.
Unless otherwise noted, passing a null argument to a constructor or method in this class will cause a NullPointerException to be thrown.