finally语句块一定执行吗？

答案是不一定。存在很多特殊情况导致 finally 语句块不执行。如：

• 直接返回未执行到 try-finally 语句块
• 抛出异常未执行到 try-finally 语句块
• 系统退出未执行到 finally 语句块

等…

代码如下

public static String test() {
	String str = null;
	int i = 0;
	if (i == 0) {
		return str;//直接返回未执行到finally语句块
	}
	try {
		System.out.println("try...");
		return str;
	} finally {
		System.out.println("finally...");
	}
}
 
public static String test2() {
	String str = null;
	int i = 0;
	i = i / 0;//抛出异常未执行到finally语句块
	try {
		System.out.println("try...");
		return str;
	} finally {
		System.out.println("finally...");
	}
}
 
public static String test3() {
	String str = null;
	try {
		System.out.println("try...");
		System.exit(0);//系统退出未执行到finally语句块
		return str;
	} finally {
		System.out.println("finally...");
	}
}