静态var被杀死但活动进入前台

Question

let's say I have 2 activities A and B. I go to B from A then hit the Home button. there are a few static vars being initialized in A.

after a few hours or days or until activity is being killed, I launch the app again from the Recent button. activity B becomes the new entry point of this app, but static vars are no longer holding any value and has no chance of getting initialized unless I redirect back to A.

my launchMode for both activities are singleTop . not sure if that matters but I've tried singleTop , singleInstance and standard none of them work. I guess my expected behavior would be the entry point is always A or any other activities if is not being killed and of course static vars are still holding value.

Thanks!

Answer 1

问题可能是因为当您的应用程序在后台运行时，Android操作系统必须清除内存才能为其他应用程序释放资源

Answer 2

• I hope those static variables are of primitive datatypes.
• Even if the Application is in background Android system kills the process after some time.
• So you can do is pass those primitive variables through Intent to ActivityB .
• Now if the Application is killed from background and brought it to Foreground same intent is used to launch the ActivityB and you can still get the passed variables.

Pass variable to ActivityB instead of static variable.

Intent intent = new Intent();
intent.putExtras("Id", 1);
intent.putExtras("Name", "kevz");
startActivity(intent, ActivityB.class);

Now in ActivityB get the passed variable values-

int Id = getIntent().getIntExtra("Id", -1); // -1 is default value.
String Name = getIntent().getStringExtra("Name", "unknown"); // unknown is default value

Answer 3

如果静态变量不起作用，则可以尝试对变量使用getter()和setter()方法。