java - 字符串分词器

Question

任何人都可以通过在代码中添加一些注释来帮助我理解这个字符串分词器的工作原理吗？如果有任何帮助，我将不胜感激!

public String[] split(String toSplit, char delim, boolean ignoreEmpty) {

    StringBuffer buffer = new StringBuffer();
    Stack stringStack = new Stack();

    for (int i = 0; i < toSplit.length(); i++) {
        if (toSplit.charAt(i) != delim) {
            buffer.append((char) toSplit.charAt(i));
        } else {
            if (buffer.toString().trim().length() == 0 && ignoreEmpty) {
            } else {
                stringStack.addElement(buffer.toString());
            }
            buffer = new StringBuffer();
        }
    }

    if (buffer.length() !=0) {
        stringStack.addElement(buffer.toString());
    }

    String[] split = new String[stringStack.size()];
    for (int i = 0; i < split.length; i++) {
        split[split.length - 1 - i] = (String) stringStack.pop();
    }

    stringStack = null;
    buffer = null;

//        System.out.println("There are " + split.length + " Words");
    return split;
}

Answer 1

不是世界上最好的写法!但是下面的评论。总的来说，它所做的是使用字符 delim 将字符串拆分为“单词”来划定它们。如果ignoreEmpty为真，则不计算空词(即两个连续的定界符作为一个)。

public String[] split(String toSplit, char delim, boolean ignoreEmpty) {

    // Buffer to construct words
    StringBuffer buffer = new StringBuffer();
    // Stack to store complete words
    Stack stringStack = new Stack();

    // Go through input string one character at a time
    for (int i = 0; i < toSplit.length(); i++) {
        // If next character is not the delimiter,
        // add it to the buffer
        if (toSplit.charAt(i) != delim) {
            buffer.append((char) toSplit.charAt(i));
        // Else it is the delimiter, so process the
        // complete word
        } else {
            // If the word is empty (0 characters) we
            // have the choice of ignoring it
            if (buffer.toString().trim().length() == 0 && ignoreEmpty) {
            // Otherwise, we push it onto the stack
            } else {
                stringStack.addElement(buffer.toString());
            }
            // Clear the buffer ready for the next word
            buffer = new StringBuffer();
        }
    }

    // If there are remaining characters in the buffer,
    // then a word rather than the delimiter ends the
    // string, so we push that onto the stack as well
    if (buffer.length() !=0) {
        stringStack.addElement(buffer.toString());
    }

    // We set up a new array to store the contents of
    // the stack
    String[] split = new String[stringStack.size()];

    // Then we pop each element from the stack into an
    // indexed position in the array, starting at the
    // end as the last word was last on the stack
    for (int i = 0; i < split.length; i++) {
        split[split.length - 1 - i] = (String) stringStack.pop();
    }

    stringStack = null;
    buffer = null;

    // Then return the array
//        System.out.println("There are " + split.length + " Words");
    return split;
}

您可以使用 string.split 编写一个更高效的程序方法，将分隔符转换为合适的正则表达式(如果 + 为真，则以 ignoreEmpty 结尾)。