assertEquals("t1,s1,r1,p1", new KuromojiItem(1, "t1", "s1", "r1", "p1").toLineString());
        assertEquals("t\"\"1,s\"\"1,r\"\"1,p\"\"1", new KuromojiItem(1, "t\"1", "s\"1", "r\"1", "p\"1").toLineString());
        assertEquals("\"t,1\",\"s,1\",\"r,1\",\"p,1\"", new KuromojiItem(1, "t,1", "s,1", "r,1", "p,1").toLineString());
        assertEquals("\"t\"\",1\",\"s\"\",1\",\"r\"\",1\",\"p\"\",1\"",

    }

    @Test
    public void test_toLineString() {
        assertEquals("aaa=>a", new StemmerOverrideItem(1, "aaa", "a").toLineString());
        assertEquals("=>", new StemmerOverrideItem(1, "", "").toLineString());
    }

        // When newInput is set back to null
        item.setNewInput(null);
        assertEquals("original", item.toLineString());
    }

    @Test
    public void test_toLineString_withEmptyInput() {
        // Test toLineString with empty original input
        StopwordsItem item = new StopwordsItem(1, "");
        assertEquals("", item.toLineString());

        item.setNewInput("new");

        // Test with item created with id=0
        ProtwordsItem newItem = new ProtwordsItem(0, "newword");
        assertEquals("newword", newItem.toLineString());
    }

    @Test
    public void test_toLineString_withEmptyInput() {
        // Test toLineString with empty input
        ProtwordsItem item = new ProtwordsItem(1, "");
        assertEquals("", item.toLineString());

        assertEquals("a=>b", new SynonymItem(1, new String[] { "a" }, new String[] { "b" }).toLineString());
        assertEquals("A,a=>B,b", new SynonymItem(1, new String[] { "A", "a" }, new String[] { "B", "b" }).toLineString());
        assertEquals("A,a", new SynonymItem(1, new String[] { "A", "a" }, new String[] { "A", "a" }).toLineString());

    }

    /**
     * Converts this item to a string representation for writing to file.
     * @return the string representation of this item
     */
    public String toLineString() {
        if (isUpdated()) {
            return StringUtils.join(newInput);
        }
        return StringUtils.join(input);
    }

    }

    /**
     * Converts the item to a string representation for writing to a file.
     *
     * @return A string in the format "input=>output".
     */
    public String toLineString() {
        if (isUpdated()) {
            return newInput + "=>" + newOutput;
        }
        return input + "=>" + output;
    }

    }

    /**
     * Converts the item to a string representation for writing to a file.
     *
     * @return The stopword as a string.
     */
    public String toLineString() {
        if (isUpdated()) {
            return StringUtils.join(newInput);
        }
        return StringUtils.join(input);
    }

    }

    /**
     * Converts the item to a string representation for writing to a file.
     *
     * @return A string in the format "input1,input2=>output1,output2".
     */
    public String toLineString() {
        if (isUpdated()) {
            if (Arrays.equals(newInputs, newOutputs)) {
                return StringUtils.join(newInputs, ",");
            }

    }

    /**
     * Returns the item as a line string.
     *
     * @return The item as a line string.
     */
    public String toLineString() {
        final StringBuilder buf = new StringBuilder(100);
        if (isUpdated()) {
            buf.append(quoteEscape(newToken));
            buf.append(',');