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Java Cookbook
book

Java Cookbook

by Ian F. Darwin
June 2001
Intermediate to advanced content levelIntermediate to advanced
888 pages
21h 1m
English
O'Reilly Media, Inc.
Content preview from Java Cookbook

Putting Strings Together with + and StringBuffer

Problem

You need to put some String pieces back together.

Solution

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 ...

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Publisher Resources

ISBN: 0596001703Supplemental ContentCatalog PageErrata