| =运算符在Java中做什么？ [英] What does the |= operator do in Java?

问题描述

在阅读 Android通知指南时，我偶然发现：

添加振动

您可以使用默认振动模式或应用程序定义的
振动模式提醒用户。

要使用默认模式，请添加DEFAULT_VIBRATE到默认值字段：

  notification.defaults | = Notification.DEFAULT_VIBRATE; 
  

这样做很清楚：它增加了 DEFAULT_VIBRATE 标记通知对象的默认标志。
但 | = 运算符在Java中是做什么用的？
它看起来像一个OR，但它是如何工作的？

你能提供一个使用数字的例子吗？

谢谢

解决方案

| = 是一个按位OR赋值运算符。它采用LHS的当前值，按位或者RHS，并将值分配回LHS（与 + = 类似的方式添加）。 / p>

例如：

  foo = 32; // 32 = 0b00100000 
 bar = 9; // 9 = 0b00001001 
 baz = 10; // 10 = 0b00001010 
 foo | = bar; // 32 | 9 = 0b00101001 = 41 
 //现在foo = 41 
 foo | = baz; // 41 | 10 = 0b00101011 = 43 
 //现在foo = 43 
  

While reading the Android guide to Notifications, I stumbled across this:

Adding vibration

You can alert the user with the the default vibration pattern or with a vibration pattern defined by your application.

To use the default pattern, add "DEFAULT_VIBRATE" to the defaults field:

notification.defaults |= Notification.DEFAULT_VIBRATE;

What this does is clear: it adds the DEFAULT_VIBRATE flag to the default flags of the notification object. But what does the |= operator do in Java? It looks like an "OR", but how does it work?

Can you provide an example using numbers?

Thanks

解决方案

|= is a bitwise-OR-assignment operator. It takes the current value of the LHS, bitwise-ors the RHS, and assigns the value back to the LHS (in a similar fashion to += does with addition).

For example:

foo = 32;   // 32 =      0b00100000
bar = 9;    //  9 =      0b00001001
baz = 10;   // 10 =      0b00001010
foo |= bar; // 32 | 9  = 0b00101001 = 41
            // now foo = 41
foo |= baz; // 41 | 10 = 0b00101011 = 43
            // now foo = 43

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