scanner.nextLine()和scanner.next()；的区别

scanner.nextLine() 和 scanner.next(); 的区别

查看 scanner.nextLine() 的源码，可以发现是一次性读完的

/**
     * Advances this scanner past the current line and returns the input
     * that was skipped.
     *
     * This method returns the rest of the current line, excluding any line
     * separator at the end. The position is set to the beginning of the next
     * line.
     *
     * <p>Since this method continues to search through the input looking
     * for a line separator, it may buffer all of the input searching for
     * the line to skip if no line separators are present.
     *
     * @return the line that was skipped
     * @throws NoSuchElementException if no line was found
     * @throws IllegalStateException if this scanner is closed
     */
    public String nextLine() {
        if (hasNextPattern == linePattern())
            return getCachedResult();
        clearCaches();

        String result = findWithinHorizon(linePattern, 0);
        if (result == null)
            throw new NoSuchElementException("No line found");
        MatchResult mr = this.match();
        String lineSep = mr.group(1);
        if (lineSep != null)
            result = result.substring(0, result.length() - lineSep.length());
        if (result == null)
            throw new NoSuchElementException();
        else
            return result;
    }

查看 scanner.next() ，可以发现是以空格为划分读的。

/**
     * Finds and returns the next complete token from this scanner.
     * A complete token is preceded and followed by input that matches
     * the delimiter pattern. This method may block while waiting for input
     * to scan, even if a previous invocation of {@link #hasNext} returned
     * <code>true</code>.
     *
     * @return the next token
     * @throws NoSuchElementException if no more tokens are available
     * @throws IllegalStateException if this scanner is closed
     * @see java.util.Iterator
     */
    public String next() {
        ensureOpen();
        clearCaches();

        while (true) {
            String token = getCompleteTokenInBuffer(null);
            if (token != null) {
                matchValid = true;
                skipped = false;
                return token;
            }
            if (needInput)
                readInput();
            else
                throwFor();
        }
    }