如果活动中有多个屏幕，如何处理活动中的后退按钮

Question

I have an activity which has multiple screens depending on which buttons the user clicks.

What should I do if I need to handle back button in this activity. ie When I press to back button it has to go previous screen of my activity.

I am really new to android. can any body help me to solve this problem

Thanks for reading.

Answer 1

I guess that by multiple screens you mean you have some layouts and change them with setContentView() . You'll have to override the back button's behavior, keep a history of user navigation between various screens (if there's no forced path) and have the back button code set content to the previous screen.

Overriding the back button is easy if you're on API >= 5: see onBackPressed() .

If you want also backward compatibility you'll find something here and here .

As this is usually all done automatically by Android with activities, consider having multiple activities instead of a single activity with multiple screens.

Answer 2

在您的活动中重写onBackPressed（）函数，并在其中写入所需的代码以进行意图触发。

Answer 3

You can do this by handling the KeyDown event and adding some condition( like taking a static variable and at each activity assign different value to the static variable ) at each actvity. See the following code:

public boolean onKeyDown(int keyCode, KeyEvent event) {


        if ((keyCode == KeyEvent.KEYCODE_BACK)) {

            if(condition 1) 
            {
                Intent i=new Intent("com.prac.A");  // A is your another activity in com.prac package   
                startAcitvity(i);
            }
            else if(condition 2)
            {
                Intent i=new Intent("com.prac.B");  
                startAcitvity(i);
            }
            else    
            {
                Intent i=new Intent("com.prac.C");  
                startAcitvity(i);
            }

         }
        return false;
    }

Hope this will help you.