[英]How do I read formatted input in Java?
Suppose my input file contains: 假设我的输入文件包含:
3 4 5 6 7 8
9
10
I want to run a while loop and read integers, so that I will get 3,4,5,6,7,8 and 10 respectively after each iteration of the loop. 我想运行一个while循环并读取整数,这样我将在循环的每次迭代后分别获得3,4,5,6,7,8和10。
This is really simple to do in C/C++ but not in Java... 这在C / C ++中很简单,但在Java中却不行......
I tried this code: 我试过这段代码:
try {
DataInputStream out2 = new DataInputStream(new BufferedInputStream(new FileInputStream(file)));
int i=out2.read();
while(i!=-1){
System.out.println(i);
i=out2.readInt();
}
} catch (IOException ex) {
}
and what I get is: 而我得到的是:
51
540287029
540418080
538982176
151599117
171511050
218762506
825232650
How do I read the integers from this file in Java ? 如何从Java中读取此文件中的整数?
One can use the Scanner
class and its nextInt
method: 可以使用
Scanner
类及其nextInt
方法:
Scanner s = new Scanner("3 4 5 6");
while (s.hasNext()) {
System.out.println(s.nextInt());
}
Output: 输出:
3
4
5
6
Basically by default, the Scanner
object will ignore any whitespace, and will get the next token. 基本上默认情况下,
Scanner
对象将忽略任何空格,并将获得下一个标记。
The Scanner
class as a constructor which takes an InputStream
as the source for the character stream, so one could use a FileInputStream
that opens the source of the text. Scanner
类作为构造函数 ,它将InputStream
作为字符流的源,因此可以使用FileInputStream
打开文本源。
Replace the Scanner
instantiation in the above example with the following: 使用以下内容替换上例中的
Scanner
实例:
Scanner s = new Scanner(new FileInputStream(new File(filePath)));
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