persistence/db/src/main/java/androidx/sqlite/db/SupportSQLiteQueryBuilder.java
private static void appendColumns(StringBuilder s, String[] columns) {
        int n = columns.length;

        for (int i = 0; i < n; i++) {
            String column = columns[i];
            if (i > 0) {
                s.append(", ");
            }
            s.append(column);
        }
        s.append(' ');
    }
/**
     * Add the names that are non-null in columns to s, separating
     * them with commas.
     */
Add the names that are non-null in columns to s, separating
them with commas.
Add the names that are non - null in columns to s separating them with commas .
private static void appendColumns(StringBuilder s, String[] columns) {
        int n = columns.length;
        for (int i = 0; i < n; i++) {
            String column = columns[i];
            if (i > 0) {
                s.append(", ");
            }
            s.append(column);
        }
        s.append(' ');
    }
private static void appendColumns ( StringBuilder s , String [ ] columns ) { int n = columns . length ; for ( int i = 0 ; i < n ; i ++ ) { String column = columns [ i ] ; if ( i > 0 ) { s . append ( ", " ) ; } s . append ( column ) ; } s . append ( ' ' ) ; }
Add the names that are non-null in columns to s, separating
 them with commas.
Add the names that are non - null in columns to s separating them with commas .