{"id":31843,"date":"2019-10-31T21:43:27","date_gmt":"2019-10-31T18:43:27","guid":{"rendered":"https:\/\/prohoster.info\/blog\/sozdanie-kalkulyatora-chaevyh-na-kotlin-kak-eto-rabotaet\/"},"modified":"2019-10-31T21:43:27","modified_gmt":"2019-10-31T18:43:27","slug":"sozdanie-kalkulyatora-chaevyh-na-kotlin-kak-eto-rabotaet","status":"publish","type":"post","link":"https:\/\/prohoster.info\/en\/blog\/news\/sozdanie-kalkulyatora-chaevyh-na-kotlin-kak-eto-rabotaet","title":{"rendered":"Creating a tip calculator in Kotlin: how it works?","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

\"Creating
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\nWe explain how to create a simple tip calculation application in Kotlin. More specifically, Kotlin 1.3.21, Android 4, Android Studio 3. This article will be particularly interesting for those starting their journey in Android app development. It provides an understanding of what works inside the application and how. <\/p>\n

Such a calculator will come in handy when you need to calculate the tip amount for a company deciding to spend time at a restaurant or caf\u00e9. Of course, not everyone tips waitstaff all the time; it's more of a Western tradition, but the development process of such an application is interesting nonetheless.
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\nHere's how the application looks in the process of working:<\/p>\n

\"Creating
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\nYou enter the desired percentage of the total amount, the number of participants in the meeting, and get the result \u2014 the amount of tip that should be left.<\/p>\n

Getting Started<\/h3>\n

\nThe complete interface of the application looks as follows:
\n\"Creating
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\n\"Creating
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\nThe first action is project base loading.<\/a><\/noindex>Open it in Android Studio 3.0 or a later version. Build and run the project and see a white screen. Everything is normal; that's how it should be.<\/p>\n

\"Creating
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\n\"Creating
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\nUser actions are arranged in chronological order within the project for clarity. To view it, go to View -> Tool Windows -> TODO.<\/p>\n

Examine the project and open colors.xml to evaluate the color palette. Text data (labels) are placed in strings.xml, and styles.xml contains several font templates.<\/p>\n

Development of the expenses section<\/h3>\n

\nOpen activity_main.xml and add the code below to LinearLayout (#1):<\/p>\n

<\/code><\/pre>\n
\nNow you can adjust the style in the values directory or play with the colors using the material.io tool.<\/a><\/noindex>.<\/p>\n
Currently, the project looks like this:<\/p>\n
\"Creating
\n As you can see, expense calculations are based on the data entered by the user. <\/i><\/p>\n
Development of the bills section<\/h3>\n
\nAdd the code below to LinearLayout after the Expense Section (#2):<\/p>\n
<! \u2014 TODO #3: Build Bill Section \u2192\n \n\u2026<\/code><\/pre>\n
\nWe close the LinearLayout after the TODOs list, and then add new code, placing it inside the LinearLayout (#3):<\/p>\n
<\/code><\/pre>\n
\nSince the main task of the application is to calculate individual expenses for each participant at the restaurant, the costPerPersonTextView is of primary importance. <\/p>\n
EditText restricts input to a single line, and this parameter should have a NumberDecimal inputType value.<\/p>\n
\"Creating
\n We run the project for testing and enter the parameters for the total damage (broken cups, plates, etc.)<\/i><\/p>\n
Development of the 'People and Tips' section<\/h3>\n
\nTo add a tip amount selection, we insert the code below into a new LinearLayout section (#4):<\/p>\n
<\/code><\/pre>\n
\nThis piece of code is necessary for accurately calculating the tip amount. The default text value is 20. ImageButtons are equipped with icons in the writable folder.<\/p>\n
We completely copy the section and add the following (#5):<\/p>\n