FileReader读到缓存区最后有字符重复问题

代码如下

public static void main(String[] args) throws Exception {
        //doSequence();

        Reader reader = new FileReader("G:/TestFiles/1.txt");
        Writer writer1 = new FileWriter("G:/TestFiles/5.txt");
        Writer writer2 = new FileWriter("G:/TestFiles/6.txt");
        char[] buffer = new char[4];
        int i = 0;
        while ((i =reader.read(buffer))!=-1) {
            //每次输出整个字符数组
            System.out.println(buffer);
            writer1.write(buffer);
            
            
        }
        writer1.flush();
        writer2.flush();
        reader.close();
        writer1.close();
        writer2.close();

    }

1.txt的内容

1234
4567

执行结果：

从执行结果可以看出最后一行的6745中多了45两个数字，这是因为在从文件中循环读取字符时，每次最多读取4个字符（个数由字符数组长度决定）。如果文件最后一次读取的字符少于4个字符，比如说最后依次读取2个字符，则只将前两个字符写入字符数组中，后两个字符没有清空，所以出现这种情况。

解决方法：每次只输出本次读取到的字符

public static void main(String[] args) throws Exception {
        //doSequence();

        Reader reader = new FileReader("G:/TestFiles/1.txt");
        Writer writer1 = new FileWriter("G:/TestFiles/5.txt");
        Writer writer2 = new FileWriter("G:/TestFiles/6.txt");
        char[] buffer = new char[4];
        int i = 0;
        while ((i =reader.read(buffer))!=-1) {

            //每次输入本次读取到的字符数组，其中i为本次读取字符个数
            String str = new String(buffer,0 ,i);
            System.out.println(str);
            writer2.write(str);

        }
        writer1.flush();
        writer2.flush();
        reader.close();
        writer1.close();
        writer2.close();

    }