检查是否设置了额外功能 [英] Check if extras are set or not

问题描述

有什么方法可以在启动活动"时检查是否通过了额外的活动?

Is there any way to check if an extra has been passed when starting an Activity?

我想做类似的事情(在活动"中的onCreate()上):

I would like to do something like (on the onCreate() in the Activity):

    Bundle extras = getIntent().getExtras();
    String extraStr = extras.getString("extra");

    if (extraStr == null) {
        extraStr = "extra not set";
    }

但这会抛出java.lang.NullPointerException.

谢谢.

推荐答案

使用示例:

Intent intent = getIntent();

if (intent.hasExtra("bookUrl")) {
    bookUrl = b.getString("bookUrl");
} else {
   // Do something else
}

此外，请使用 Intent.getStringExtra(String name) 直接用于处理NullPointerException的意图，如果没有传递任何额外内容.

Also, use Intent.getStringExtra(String name) directly on the intent to handle the NullPointerException if no extras were passed.

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