对象引用在finally块中设置为null [英] object reference set to null in finally block

问题描述

public void testFinally(){
System.out.println(setOne().toString());

}

protected StringBuilder setOne(){
StringBuilder builder=new StringBuilder();
try{
builder.append("Cool");
return builder.append("Return");
}finally{
builder=null; /* ;) */
}
}

为什么输出是CoolReturn，而不是null？

why output is CoolReturn, not null?

问候，

Mahendra Athneria

Regards,
Mahendra Athneria

推荐答案

表达式被计算为return语句中的值，这是将返回的值。在返回语句的表达式求值部分之后执行finally块。

The expression is evaluated to a value in the return statement, and that's the value which will be returned. The finally block is executed after the expression evaluation part of the return statement.

当然，finally块可以修改对象的内容由返回值引用 - 例如：

Of course, the finally block could modify the contents of the object referred to by the return value - for example:

finally {
  builder.append(" I get the last laugh!");
}

在这种情况下，控制台输出将是CoolReturn我笑到最后！ - 但它不能改变实际返回的值。

in which case the console output would be "CoolReturn I get the last laugh!" - but it can't change the value which is actually returned.

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