androidで予測変換機能を1文字目から起動させたい

以下のコードでAutoCompleteTextが現状２文字以上入力した場合にsetCursorToStringConverterが起動します。
１文字目で起動させたい場合はどのようにすればよいですか。

AutoCompleteTextView inputTextView = (AutoCompleteTextView) findViewById(R.id.m_name);
Cursor m_cursor = db3.query(DB_TABLE, new String[]{"rowid as _id", "n_data" },null, null,null, null, null);
SimpleCursorAdapter M_adapter2 = new SimpleCursorAdapter(getApplicationContext(),
                        android.R.layout.simple_spinner_dropdown_item,
                        m_cursor,
                        new String[]{"n_data"},
                        new int[]{android.R.id.text1},
                        0) {
                };
M_adapter2.setCursorToStringConverter(new SimpleCursorAdapter.CursorToStringConverter() {
                    @Override
                    public String convertToString(Cursor m_cursor) {
                        return m_cursor.getString(m_cursor.getColumnIndex("n_data"));
                    }
M_adapter2.setFilterQueryProvider(new FilterQueryProvider() {
                public Cursor runQuery(CharSequence constraint) {
                        String str = constraint.toString();
                        str = "%" + str + "%";
                        helper = new DBOpenHelper(ItemListActivity.this);// DB作成
                        Cursor m_cursor = helper.getReadableDatabase().query(
                                DB_TABLE4, new String[]{"rowid as _id", "n_data"},
                                "n_data LIKE '' || ? || '%'  ", new String[]{str},
                                null,null, null);
                        return m_cursor;
                    }
                });
inputTextView2.setAdapter(M_adapter2);