App Inventor 2
Programming mobile phones with Android 
by App Inventor 2 - Juan Antonio Villalpando

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Storage

54B.- Passing data between screens. Another method.

ip54B_datas_between_screen

- Presentation.

- In the previous tutorial we saw that we could pass data through TinyDB comes screens. Let's see another method.

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- In this example we will write a data in TextBox and click the button "Goto Screen". The current screen will close and the other screen data to be passed.

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Design Screen1

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Blocks Screen1

- Block: opens another screen with start value is in the part of Control .
- Block: get start value is in the part of Control.
- Block: when Screen1.Initialize is in the part of Screen1.

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Add another window, click on Add Screen.

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Design Screen2

- We set the background color of the Screen2 in Yellow to be easily distinguished.

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Blocks Screen2

- Block: opens another screen with start value is in the part of Control.
- Block: get initial value is in the part of Control .
- Block: when Screen2.Initialize is in the part of Screen2.

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Comments

- We send data from one screen to another.
- Note that the two variables: scr1 and scr2 are in both Screen.
- Sometimes the emulator does not work well with screen change, we must restart it .

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54C.- Pass several data between screens.

ip54c_dats_between_screen

- Presentation.

- In the previous tutorial we saw how to have a data from one screen to another, but ... what if we spend several data?

- Then we use a List.

We will forward name, age and city of one screen to another by the method we are seeing on this page.

In this case we created a List called data.

Insert the data: name old city

on the list.

We turn to the other screen Initial value is the data list.

On the screen Screen2 receive the data list of the previous screen.

We draw each item in the list and assign data to variables.

Every time we enter new data, the previous data is deleted from the list.

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Design Screen1

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Blocks Screen1

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Design Screen2

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Blocks Screen2

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Trick:

Sometimes we are making emulations to test the code and we need the input screen is updated. One trick is to pull out and put a new button anywhere on the screen and then delete it, so the Screen1 is updated.

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