Java Checked 和 UnChecked Exception 的区别

这个问题已经在不仅一次的面试中出现了，因此收录到博客里！

Checked: 能在compile时被检查到

比如：

import java.io.*;

class Main {
public static void main(String[] args) throws IOException {
FileReader file = new FileReader("C:\\test\\a.txt");
BufferedReader fileInput = new BufferedReader(file);

// Print first 3 lines of file "C:\test\a.txt"
for (int counter = 0; counter < 3; counter++)
System.out.println(fileInput.readLine());

fileInput.close();
}
}

UnChecked：只能在runtime（运行时）才能被检查到的。

如除以0

class Main {
public static void main(String args[]) {
int x = 0;
int y = 10;
int z = y/x;
}
}

再来一张继承关系图：

+-----------+
| Throwable |
+-----------+
/         \
/           \
+-------+          +-----------+
| Error |          | Exception |
+-------+          +-----------+
/  |  \           / |        \
\________/	  \______/    	 \
+------------------+
unchecked	 checked	| RuntimeException |
+------------------+
/   |    |      \
\_________________/

unchecked

http://www.geeksforgeeks.org/checked-vs-unchecked-exceptions-in-java/