在finally块中为变量赋值null [英] Assigning null to variable in finally block

问题描述

以下代码的输出为Test Passed;有人向我解释为什么？

The output of the following piece of code is "Test Passed"; can someone explain to me why ?

public class Test {
    public static void main(String args[]) {
        System.out.println(new Test().print());
    }

    protected StringBuilder print() {
        StringBuilder builder = new StringBuilder();
        try {
            builder.append("Test ");
            return builder.append("Passed!!!");
        } finally {
        builder = null; 
    }
}

推荐答案

Java的作用如下：

Basically, what Java does is the following:

StringBuilder valueToReturn = builder.append("Passed!!!");
executeFinallyBlock();
return valueToReturn;

无论你在finally块内做什么，Java都保留了对返回值的引用，并返回该参考。所以它变成：

Whatever you're doing inside the finally block, Java has kept a reference to the value to return, and returns that reference. So it becomes:

StringBuilder valueToReturn = builder.append("Passed!!!");
builder = null;
return valueToReturn;

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