Java File.createTempFile() 抛出 NullPointerException

Question

这个 Java 1.8.0_102 程序:

import java.io.File;
import java.io.IOException;

public class Main {

    public static void main(String[] args) {
        File tempFile = null;

        try {
            tempFile = File.createTempFile(null,  null);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

抛出这个异常:

Exception in thread "main" java.lang.NullPointerException
    at java.io.File.createTempFile(Unknown Source)
    at java.io.File.createTempFile(Unknown Source)
    at Main.main(Main.java:10)

根据 Javadocs，两个参数都可以为空。知道为什么会抛出这个特殊异常吗？

Answer 1

根据JavaDoc，前缀不能为空

Parameters:

prefix - The prefix string to be used in generating the file's name; must be at least three characters long

suffix - The suffix string to be used in generating the file's name; may be null, in which case the suffix ".tmp" will be used