June 2001
Intermediate to advanced
888 pages
21h 1m
English
You need to put some String pieces back together.
Use
string concatenation: the
+ operator. The compiler will construct a
StringBuffer for you and use its append( )
methods. Or better yet,
construct it yourself. Conveniently, the append( )
method returns a reference to the
StringBuffer itself, so that statements like the
.append(...).append(...) are fairly common. You
might even see this third way in a toString( )
method. Example 3-2 shows the three ways of
concatenating strings.
Example 3-2. StringBufferDemo.java
/**
* StringBufferDemo: construct the same String three different ways.
*/
public class StringBufferDemo {
public static void main(String[] argv) {
String s1 = "Hello" + ", " + "World";
System.out.println(s1);
// Build a StringBuffer, and append some things to it.
StringBuffer sb2 = new StringBuffer( );
sb2.append("Hello");
sb2.append(',');
sb2.append(' ');
sb2.append("World");
// Get the StringBuffer's value as a String, and print it.
String s2 = sb2.toString( );
System.out.println(s2);
// Now do the above all over again, but in a more
// concise (and typical "real-world" Java) fashion.
StringBuffer sb3 = new StringBuffer( ).append("Hello").
append(',').append(' ').append("World");
System.out.println(sb3.toString( ));
// Exercise for the reader: do it all again but without
// creating ANY temporary variables.
}
}In fact, all the methods that modify more than one character of a
StringBuffer’s contents ...