Java™ Application Development on Linux - Dator

60Chapter 3An Experienced Programmer’s Introduction to Javaeach with unique types of parameters. For example, the String class has manydifferent constructors, including one which constructs a new String from adifferent String and another that constructs a new String from an arrayof bytes.String strbystr = new String(oldstr);String strbyarr = new String(myByteArray);3.2.2.2 StringsOne of the most commonly used classes is the String class. It comes alreadydefined as part of Java and has some special syntax for initialization whichmakes it look familiar. Whereas other objects need a new keyword and a constructorcall, a String object can be created and initialized with the intuitivedouble quotes, as in:String xyz="this is the stringtext";The compiler also makes a special allowance for Strings with respect tothe plus sign (+). It can be used to concatenate two Strings into a third, newString.String phrase = "That is"String fullsent = phrase + " all.";It is worth noting that Strings do not change—they are immutable.When you assign a String the value of one String plus another, there’s a lotof String object creation going on behind the scenes. If you need to do a lotof concatenation of Strings, say inside loops, then you should look into theuse of the StringBuffer object. See Appendix A of Thinking in Java, 3rd ed.,the section titled Overloading “+” and the StringBuffer, for a full discussionof the tradeoffs here.There are a variety of methods for String—ones that will let you makesubstrings, search for substrings at the start or end or anywhere in the string,or check for equality of two strings.Table 3.2 shows some of the most useful methods associated with Stringobjects.