Question

我写了一个循环遍历字符串并添加＆＃39; / n＆＃39;创建参数中给出的行长度。这种描述不是最好的，但很难描述，所以请看下面的代码。提前谢谢！

我的代码：

public static String lineLength(String str, int length){
        int totalLength = 0; //total length of the document
        int lengthConst = 0; //constant value of the length for the loop
        int nLength = 0; // length of \n = 2 characters

        String work1, work2; //Strings to work with in the loop. Used as string buffers in substrings

        if(str != null){
            totalLength = str.length();
            lengthConst = length;
        }
        if(length < 1){
            throw new NullPointerException("Length must be >= 1");
        }

        /*
        Main Loop: check again if length is not zero, check if totalLength is not zero,
        check if pseudoCursor is not zero, check if length is less than or equal to totalLength
        */
        while((length != 0) && (totalLength != 0) && (lengthConst != 0) && (length <= totalLength)){
            work1 = str.substring(0, length); //store string of beginning to line length
            work2 = str.substring(length + nLength, str.length()); //store string from length to end

            work1 = work1.concat("\n"); //add new line
            str = work1.concat(work2); //add work1 and work2 and store in str

            nLength += 1; //nLength increases by 2 because we are going to add another \n
            length += length; 
        }

        return str;
    }

当提供字符串＆＃34; Daniel＆＃34;并且新行长度为2这是打印到控制台时的运行：

run:
Da
n
el
BUILD SUCCESSFUL (total time: 4 seconds)

Answer 1

我建议使用for循环。我认为这比你现在做的要容易。通常 for循环如下：

for(START POSITION, CONTROL, ITERATION PATTERN){
    CODE
}

我在这里阅读了有关for循环的更多内容：

http://www.tutorialspoint.com/java/java_loop_control.htm

http://docs.oracle.com/javase/tutorial/java/nutsandbolts/for.html

String对象有一个方法.length()，它将用于控制循环。你想迭代2（因为这就是你将它们分开的方式）。你也想从1开始（通常起始位置是0但在这种情况下我们想要1）：

String word = "Daniel";//starting word
String outputWord = "";//make it empty quotes so you can concatenate to it.
//if the size of word is less than 2, then print so
//else do the code below
for(int i = 1; i < word.length(); i = i+2){
    outputWord = outputWord + word.get(i-1) + word.get(i) + "\n";
}
//check if the length was of word was odd. if so, then add the last character to outputWord
System.out.println(outputWord);

注意：只有在word变量的大小至少为2时才会生效。我会把错误处理留给你写。你也想要处理奇数长度的情况。

Answer 2

这是一个简化版本

public static String lineLength(String str, int length) {
    StringBuilder sb = new StringBuilder();

    while(true) {
        if(str.length() <= length) {
            sb.append(str);
            break;
        } 

        sb.append(str.substring(0, length));
        sb.append("\n");
        str = str.substring(length);
    }

    return sb.toString();
}

您仍然需要了解解决方案的错误，以便从中学习并将这些知识应用到您将来编写的代码中。在调试器中逐步执行此代码和原始代码，并仔细观察发生的情况。

Java字符串新行循环

2 个答案: