在Android Intent中的putExtra中传递null会导致编译时错误吗？

Question

I'm trying to use putExtra(String,String) in my code to pass null . As the parameter suggests the second parameter can be null as it is a string and I can send it

this.getIntent().putExtra(AppConstant.TestString, null);

When i use the above code it gives me error saying :

The method putExtra(String, String) is ambiguous for the type Intent

However it allows me to use :

this.getIntent().putExtra(AppConstant.TestString, "");

Kindly enlighten me on this. Thanks in advance.

Answer 1

When you use null , the compiler doesn't know which is the type you want to use and cannot decide which overload of the method to use.

You can cast your null to String to inform compiler which method you use:

this.getIntent().putExtra(AppConstant.TestString, (String)null);

Alternatively, you can create a variable and set it to null :

String param = null;
this.getIntent().putExtra(AppConstant.TestString, param);

Answer 2

问题是因为第二个参数为null它无法告诉您要调用哪个方法： putExtra(String name, float value) ， putExtra (String name, byte[] value) ， putExtra (String name, long[] value)等等......

Answer 3

This is probably because Android can not determine what you are passing ( String , boolean , int ) when you use

this.getIntent().putExtra(AppConstant.TestString, null);

but when you use

this.getIntent().putExtra(AppConstant.TestString, "");

it knows that you are passing it as a String

Answer 4

Use intent.removeExtra(extraName) instead. It clears the extra and is more clean than using typecasting in putExtra.

https://developer.android.com/reference/android/content/Intent.html