从文件中读取后的java嵌套循环

Question

我有一个数组

arr[] = {"a", "b", "c"}

和

下面的文本文件

1
2
3
4
5

我想编写一个将在

下面生成的循环

1
2
3
4
5
Hello from a
1
2
3
4
5
Hello from b
1
2
3
4
5
Hello from c

下面是我试过的

String a;
for (int i =0; i<arr.length; i++) {         
while (a = br.readLine() ){

    fileWriter.write(a + "\n")
}
fileWriter.write("Hello from "  + arr[i] +"\n");
}

我得到的是......

1
2
3
4
5
Hello from a
Hello from b    
Hello from c

Answer 1

我会首先读取整个文件，将其存储在内存中并进行循环。正如@AntonH所说，br（我想是一个BufferReader）会在一段时间内到达文件的末尾而你不会再将其指向开头。

String a;
String b = "";          
while (a = br.readLine() ){
    b += a + "\n"
}
for (int i =0; i<arr.length; i++) {
    fileWriter.write(b + "Hello from "  + arr[i] + "\n");
}