java - android从文件中读取

Question

我是 android 的新手，在看书时无法理解循环中新分配的原因。在循环之前做一次还不够吗？

        FileInputStream fIn =
                openFileInput("textfile.txt");
        InputStreamReader isr = new
                InputStreamReader(fIn);
        char[] inputBuffer = new char[READ_BLOCK_SIZE];
        String s = "";
        int charRead;
        while ((charRead = isr.read(inputBuffer))>0)
        {
            //---convert the chars to a String---
            String readString =
            String.copyValueOf(inputBuffer, 0,
            charRead);
            s += readString;
            inputBuffer = new char[READ_BLOCK_SIZE];
        }

Answer 1

来自 String.copyValueOf javadoc :

  /**
 * Creates a new string containing the specified characters in the character
 * array. Modifying the character array after creating the string has no
 * effect on the string.
 *
 * @param start
 *            the starting offset in the character array.
 * @param length
 *            the number of characters to use.

因此没有理由在循环中创建一个新的 char[]。