javaparser-core/src/main/java/com/github/javaparser/utils/SeparatedItemStringBuilder.java

package com.github.javaparser.utils;

/**
 * Builds a string containing a list of items with a prefix, a postfix, and a separator.
 * <br/>Example: (1,2,3) which has prefix "(", separator ",", postfix ")" and the items 1 through 3.
 * <p/>Java 8 offers the very nice Collectors.joining(String, String, String) which does the same thing.
 */
public class SeparatedItemStringBuilder {
    private final String separator;
    private final String postfix;
    private boolean hasItems = false;
    private StringBuilder builder;

    public SeparatedItemStringBuilder(String prefix, String separator, String postfix) {
        builder = new StringBuilder(prefix);
        this.separator = separator;
        this.postfix = postfix;

    }

    /**
     * Add one item. Either pass a string, or a format for String.format and corresponding arguments.
     */
    public SeparatedItemStringBuilder append(CharSequence format, Object... args) {
        if (hasItems) {
            builder.append(separator);
        }
        builder.append(String.format(format.toString(), args));
        hasItems = true;
        return this;
    }

    public boolean hasItems() {
        return hasItems;
    }

    /**
     * Convert the builder into its final string representation.
     */
    @Override
    public String toString() {
        // This order of toStringing avoids debuggers from making a mess.
        return builder.toString() + postfix;
    }
}