A simple string templating utility.

StringTemplate.java

public class StringTemplate
{

    public static final String DEFAULT_START = "{";
    public static final String DEFAULT_END = "}";

    private String[] chunks;

    public StringTemplate( String text )
    {
        this( text, DEFAULT_START, DEFAULT_END );
    }

    public StringTemplate( String text, String start, String end )
    {
        this.chunks = parse( text, start, end );
    }

    public String generate( Map<String, ? extends Object> map, String nullValue )
    {
        if (chunks == null)
        {
            return null;
        }
        
        StringBuilder sb = new StringBuilder();

        for (int i = 0; i < chunks.length; i++)
        {
            if ((i & 1) == 0)
            {
                sb.append( chunks[i] );
            }
            else
            {
                Object value = map.get( chunks[i] );

                sb.append( value == null ? nullValue : value.toString() );
            }
        }

        return sb.toString();
    }

    public static String[] parse( String text, String start, String end )
    {
        if (text == null || start == null || start.length() == 0 || end == null || end.length() == 0)
        {
            return null;
        }
        
        List<String> chunkList = new ArrayList<String>();

        int last = 0;
        int current = 0;
        int next = 0;

        while (current != -1)
        {
            current = text.indexOf( start, last );

            if (current == -1)
            {
                chunkList.add( text.substring( last ) );
            }
            else
            {
                int wordBegin = current + start.length();

                next = text.indexOf( end, wordBegin );

                if (next == -1)
                {
                    return null;
                }
                else
                {
                    chunkList.add( text.substring( last, current ) );
                    chunkList.add( text.substring( wordBegin, next ) );
                }

                last = next + end.length();
            }
        }

        return chunkList.toArray( new String[chunkList.size()] );
    }

    public static void main( String[] args )
    {
        StringTemplate st = new StringTemplate( "Hello, ${a}! ${ff}", "${", "}" );

        Map<String, String> map = new HashMap<String, String>();
        map.put( "a", "world" );

        String result = st.generate( map, "meow" );

        System.out.println( result );
    }

}