Strings are extremely useful but at the same time resource intensive too. In programs where numerous strings are used which need to be altered every now and then, it is advisable to use the StringBuffer or the StringBuilder class.
The java.lang.StringBuffer and java.lang.StringBuilder classes should be used when you have to make a lot of modifications to strings of characters. As we discussed in the previous chapter, String objects are immutable, so if you choose to do a lot of manipulations with String objects, you will end up with a lot of abandoned String objects in the String pool. On the other hand, objects of type StringBuffer and StringBuilder can be modified over and over again without leaving behind a great list of discarded String objects.
StringBuffer vs. StringBuilder
The StringBuilder class was added in Java 5. It has exactly the same API as the StringBuffer class, except StringBuilder is not thread safe. In other words, its methods are not synchronized. (For now just know that syncrhonized is used for thread safety and causes an overhead in terms of performance) Sun recommends that you use StringBuilder instead of StringBuffer whenever possible because StringBuilder will run faster. So apart from synchronization, anything we say about StringBuilder's methods holds true for StringBuffer's methods, and vice versa.
Both StringBuffer and StringBuilder are much faster when compared to the String class when it comes to manipulating string objects. But, the StringBuilder is usually faster than the StringBuffer because the StringBuffer object is internally synchronized so, due to the multi-threading overhead the StringBuilder is faster. So, if your application is multi-threaded and the object could be accessed/modified by multiple threads use the StringBuffer, else use the StringBuilder.
The StringBuilder class was added in Java 5. It has exactly the same API as the StringBuffer class, except StringBuilder is not thread safe. In other words, its methods are not synchronized. Sun recommends that you use StringBuilder instead of StringBuffer whenever possible because StringBuilder will run faster. So apart from synchronization, anything we say about StringBuilder's methods holds true for StringBuffer's methods, and vice versa.
Here's how to create a StringBuffer instance.StringBuffer sb = new StringBuffer();sb.append("Add this is to the buffer");// ...Note the StringBuffer has synchronized methods so if it is only accessed in a single thread context then a StringBuilder is preferred. StringBuffer and StringBuilder both implement the Appendable and CharSequence interfaces so can be used interchangeably.
Strings are extremely useful but at the same time resource intensive too. In programs where numerous strings are used which need to be altered every now and then, it is advisable to use the StringBuffer or the StringBuilder class. The java.lang.StringBuffer and java.lang.StringBuilder classes should be used when you have to make a lot of modifications to strings of characters. As we discussed in the previous chapter, String objects are immutable, so if you choose to do a lot of manipulations with String objects, you will end up with a lot of abandoned String objects in the String pool. On the other hand, objects of type StringBuffer and StringBuilder can be modified over and over again without leaving behind a great list of discarded String objects.
In Java, String is a class that represents an immutable string, that is a sequence of characters that can never change. Any modification to the String will have to create a new String object. A StringBuffer (and in Java 1.5 and up, a StringBuilder) is a mutable string object that can be modified at runtime. The advantages of using Strings are that the String is generally lighter and faster to use where the String isn't going to change. When building a long String of text by making changes to one object over time, you should use a StringBuilder or StringBuffer (in Java 1.4 or when synchronization is important).
Both StringBuffer and StringBuilder are much faster when compared to the String class when it comes to manipulating string objects. But, the StringBuilder is usually faster than the StringBuffer because the StringBuffer object is internally synchronized so, due to the multi-threading overhead the StringBuilder is faster. So, if your application is multi-threaded and the object could be accessed/modified by multiple threads use the StringBuffer, else use the StringBuilder.
The StringBuilder class was added in Java 5. It has exactly the same API as the StringBuffer class, except StringBuilder is not thread safe. In other words, its methods are not synchronized. (For now just know that syncrhonized is used for thread safety and causes an overhead in terms of performance) Sun recommends that you use StringBuilder instead of StringBuffer whenever possible because StringBuilder will run faster. So apart from synchronization, anything we say about StringBuilder's methods holds true for StringBuffer's methods, and vice versa.
The StringBuilder class was added in Java 5. It has exactly the same API as the StringBuffer class, except StringBuilder is not thread safe. In other words, its methods are not synchronized. Sun recommends that you use StringBuilder instead of StringBuffer whenever possible because StringBuilder will run faster. So apart from synchronization, anything we say about StringBuilder's methods holds true for StringBuffer's methods, and vice versa.
Here's how to create a StringBuffer instance.StringBuffer sb = new StringBuffer();sb.append("Add this is to the buffer");// ...Note the StringBuffer has synchronized methods so if it is only accessed in a single thread context then a StringBuilder is preferred. StringBuffer and StringBuilder both implement the Appendable and CharSequence interfaces so can be used interchangeably.
That depends what you use them for. A StringBuffer (or StringBuilder) has better performance when you need to build a long string out of small parts, because it allows to change the StringBuffer by appending to it, rather than creating new objects for every change. A String has better performance when modification is not necessary, because it has less overhead, and the JVM can assume it will never change.
public synchronized StringBuffer append(String s)This method will update the value of the object that invoked the method, whether or not the return is assigned to a variable. This method will take many different arguments, including boolean, char, double, float, int, long, and others, but the most likely use on the exam will be a String argument-for example,StringBuffer sb = new StringBuffer("ferrari ");sb.append("car");System.out.println(sb); // output is "ferrari car"public StringBuffer delete(int start, int end)This method returns a StringBuilder object and updates the value of the StringBuilder object that invoked the method call. In both cases, a substring is removed from the original object. The starting index of the substring to be removed is defined by the first argument (which is zero-based), and the ending index of the substring to be removed is defined by the second argument (but it is one-based)! Study the following example carefully:StringBuffer sb = new StringBuffer ("0123456789");System.out.println(sb.delete(4,6));// output is "01236789"public StringBuffer insert(int offset, String s)This method returns a StringBuilder object and updates the value of the StringBuilder object that invoked the method call. In both cases, the String passed in to the second argument is inserted into the original StringBuilder starting at the offset location represented by the first argument (the offset is zero-based). Again, other types of data can be passed in through the second argument (boolean, char, double, float, int, long, and so on), but the String argument is the one you're most likely to see:StringBuffer sb = new StringBuffer ("ferrari");sb.insert(4, "---");System.out.println( sb ); // output is "ferr---ari"
Strings are extremely useful but at the same time resource intensive too. In programs where numerous strings are used which need to be altered every now and then, it is advisable to use the StringBuffer or the StringBuilder class. The java.lang.StringBuffer and java.lang.StringBuilder classes should be used when you have to make a lot of modifications to strings of characters. As we discussed in the previous chapter, String objects are immutable, so if you choose to do a lot of manipulations with String objects, you will end up with a lot of abandoned String objects in the String pool. On the other hand, objects of type StringBuffer and StringBuilder can be modified over and over again without leaving behind a great list of discarded String objects.
In Java, String is a class that represents an immutable string, that is a sequence of characters that can never change. Any modification to the String will have to create a new String object. A StringBuffer (and in Java 1.5 and up, a StringBuilder) is a mutable string object that can be modified at runtime. The advantages of using Strings are that the String is generally lighter and faster to use where the String isn't going to change. When building a long String of text by making changes to one object over time, you should use a StringBuilder or StringBuffer (in Java 1.4 or when synchronization is important).
In Java, you might use the StringBuffer class. Convert the integer to a StringBuffer, use the method to revert it - I believe it is revert() or something; look it up in the documentation - then print it.In Java, you might use the StringBuffer class. Convert the integer to a StringBuffer, use the method to revert it - I believe it is revert() or something; look it up in the documentation - then print it.In Java, you might use the StringBuffer class. Convert the integer to a StringBuffer, use the method to revert it - I believe it is revert() or something; look it up in the documentation - then print it.In Java, you might use the StringBuffer class. Convert the integer to a StringBuffer, use the method to revert it - I believe it is revert() or something; look it up in the documentation - then print it.
stringbuilder
Set length of buffer to zero to clear a StringBufferinstance.Example:StringBuffer buf = new StringBuffer();// ... use bufferbuf.setLength(0);// buffer now has zero length
You can create a separate string initially empty. Then using a loop, start at the end of the string and add it to the end of the other string. At the end of the loop, the other string would contain the reverse.