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Design My Android Layout

, 9 Aug 2014 CPOL
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Help Beginners to move their 1st step into developing their android application

Introduction

Thinking as an Android Developer, I have a project and now it's time for starting real development --How should i begin?-- Probably this is the first question that comes in mind for a beginner developer.

The answer is easy : It's XML Layout for my first Activity or we can call it my first Screen that appears to user, but which Layout should i implement? this depends on what you want to do, so in this article we will discuss all possible Layouts you can use, as well as controls that you would need.

Android XML Layouts

  1. Relative Layout
  2. Linear Layout
  3. Grid View
  4. List View

Android Controls

  1. Edit Text
  2. Button / Image Button
  3. CheckBox
  4. Radio Button / Radio Group

1. Android XML Layout

1.1 Relative Layout

After developing some applications, You will find that Relative Layout is one of the most used layout in your application, that's why I decided to discuss it first.

You can use this layout to position items in a relative position to each others as well as position siblings as we see in this example.

Example 1

We want to display a title in center of the screen and bellow it a Text Editor and right to the Text Editor a Button

1. Open Your Project and Go to activity_main.xml... You should find it as below 

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/hello_world" />

</RelativeLayout>

2. It's time for some modifications. Our first modification is to display Hello World in the center of the screen 

//just add these lines to your TextView
android:id="@+id/TextView"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"

//Your code should look like this
<TextView
  android:id="@+id/TextView"  //Give an ID to your Control so you can position relative to
  android:layout_width="wrap_content" //This stretch width to fit whole content
  android:layout_height="wrap_content" //This stretch height to fit whole content 
  android:layout_centerHorizontal="true" // Used to center TextView Horizontaly
  android:layout_centerVertical="true"  // Used to center TextView Verticaly
  android:text="@string/hello_world" />  //Display Text that is saved in string.xml

3. Now, Let's Add the Edit Text and Button

//Implemented EditText and Button    
<EditText 
        android:id="@+id/EditTextRelativeLayout"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:hint="Enter Your Name" //set the hint as normal text instead of string.xml
        android:layout_below="@+id/TextView"> //Set EditText Below of TextView 
        </EditText>

<Button
        android:id="@+id/Button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/ButtonSubmit"
        android:layout_below="@id/TextView" //Set EditText Below of TextView
        android:layout_toRightOf="@id/EditTextRelativeLayout">//and right of EditText
        </Button>

4. We finished our first layout but there is other parameters rather than "wrap_content" also what if i want to insert both EditText and Button inside another Layout and control it instead of controlling both EditText and Button

    - I changed EditText Layout:Width to "Fill_Parent" that stretches the EditText to fit all the width and same for Layout:Height, that made Button disappear because its position is relative to EditText and it's out of the screen which isn't acceptable in our case that's why using wrap_content is better in our example.

<EditText 
        android:id="@+id/EditTextRelativeLayout"
        android:layout_width="fill_parent"  // used fill_parent
        android:layout_height="fill_parent" // used fill_parent
        android:hint="Enter Your Name"
        android:layout_below="@+id/TextView"></EditText>

     - As we see both EditText and Button are not  centered horizontally. The best way to center both in one step is to place both fields inside another layout and center this layout as the below code

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <TextView
        android:id="@+id/TextView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:text="@string/hello_world" />

    //Removed layout_below from both EditText & Button, and added it to our new RelativeLayout
    //as well as adding layout_centerHorizontal for this Layout
    <RelativeLayout
        android:id="@+id/CenterLayout"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/TextView"
        android:layout_centerHorizontal="true" >

        <EditText
            android:id="@+id/EditTextRelativeLayout"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:hint="Enter Your Name" >
        </EditText>

        <Button
            android:id="@+id/Button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_toRightOf="@id/EditTextRelativeLayout"
            android:text="@string/ButtonSubmit" >
        </Button>
    </RelativeLayout>

</RelativeLayout>

#NOTE_1: DO NEVER INSERT CONSTANT VALUE LIKE 26dp INSIDE LAYOUT_WIDTH OR LAYOUT_HEIGHT...ALWAYS REMEMBER THERE ARE DIFFERENT SCREEN SIZES

 

1.2 Linear Layout

Probably,Your second option will be Linear Layout. Using this one, you only have 2 options to list items below each other (1 item per column) or list your items vertically (1 item per row).

You would need something like this if you are implementing a Movie List as example.

//Add Linear Layout
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" > //This one sets to place 1 item per row

    <EditText
        android:id="@+id/EditTextRelativeLayout_One"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:hint="Enter Your Name ( 1 )" >
    </EditText>

    <EditText
        android:id="@+id/EditTextRelativeLayout_Two"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:hint="Enter Your Name ( 2 )" >
    </EditText>

</LinearLayout>
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal" > // I used horizontal Orientation

    <EditText
        android:id="@+id/EditTextRelativeLayout_One"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:hint="Enter Your Name ( 1 )" >
    </EditText>

    <EditText
        android:id="@+id/EditTextRelativeLayout_Two"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:hint="Enter Your Name ( 2 )" >
    </EditText>

</LinearLayout>

What if i want to add 1 BIG Item that contains both EditText & Button Per Row, this is very simple we can implement Relative Layout inside our Linear Layout as below

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    //Added 1st Item in Row 
    <RelativeLayout
        android:id="@+id/Rel1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" >

        <EditText
            android:id="@+id/EditTextRelativeLayout_One"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:hint="Enter Your Name ( 1 )" >
        </EditText>

        <Button
            android:id="@+id/Button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_toRightOf="@id/EditTextRelativeLayout_One"
            android:text="@string/ButtonSubmit" >
        </Button>
    </RelativeLayout>

    //2nd Row
    <RelativeLayout
        android:id="@+id/Rel2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" >

        <EditText
            android:id="@+id/EditTextRelativeLayout_Two"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:hint="Enter Your Name ( 2 )" >
        </EditText>

        <Button
            android:id="@+id/Button2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_toRightOf="@id/EditTextRelativeLayout_Two"
            android:text="@string/ButtonSubmit" >
        </Button>
    </RelativeLayout>

</LinearLayout>

1.3 GridView / ListView

Your third option layout is GridView that displays item in 2 dimensional, and a scrollable grid Or ListView that represents items in 1-D dimension. I'll talk in more details in GridView but everything is the same for ListView.

You can decide number of columns for your grid or fit it automatically depeding on the screen size as follow

//here 3 columns
<?xml version="1.0" encoding="utf-8"?>
<GridView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" 
    android:numColumns="3">
    

</GridView>

//Or set numColumns to auto_fit,depeding on column width relative to screen size
<?xml version="1.0" encoding="utf-8"?>
<GridView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" 
    android:numColumns="auto_fit">
    

</GridView>

Now, how can i add items to my grid? You can't insert it from layout as before, your application will crash. You have to add Grid Items through code.

1.Create Item Layout that will be filled inside your grid

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
    
<EditText 
    android:id="@+id/txtGrid"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"/>
    
</LinearLayout>

 

2. Access Grid from codeand set its adapter class that helps to bind data to grid

GridView gridview = (GridView) findViewById(R.id.myGrid);
gridview.setAdapter(new GridAdatper(this.getApplicationContext()));

3.Right-Click on GridAdatper and Create a class as well as adding your constructor that accepts application context

Context _C;

public GridAdatper(Context applicationContext) {
    // TODO Auto-generated constructor stub
    _C = applicationContext;
}

4. Bind Data through your Adapter inside getView function

public View getView(int arg0, View arg1, ViewGroup arg2) {
        // TODO Auto-generated method stub
        EditText editText;
        View grid_item = null;
        LayoutInflater inflater = (LayoutInflater) _C
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        if (arg1 == null) {  // if it's not recycled, initialize some attributes
            grid_item = new View(_C);
            grid_item = inflater.inflate(R.layout.grid_item, null);
            editText = (EditText)grid_item.findViewById(R.id.txtGrid);
            
            editText.setHint(InputData[arg0]);
        } else {
            grid_item = (View) arg1;
        }

        return grid_item;
}

2. Android Controls

I will talk mainly about some parameters that fits specially with each control, and how to access this control into your code 

2.1 EditText

EditText Control is your way to read input from user

<EditText
            android:id="@+id/EditTextRelativeLayout"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:password="true" //This parameter sets password to true and display text as *
            android:maxLength="100" //We can set maxLength 
            android:hint="Edit Text"
            android:textColorHint="@android:color/holo_blue_dark"> //Also Hint Color is changable
        </EditText>

How can i access this control and change some parameters in code?

EditText txt_Edit1 = (EditText) findViewById(R.id.EditTextRelativeLayout); //Load Item by its ID
txt_Edit1.setHint("");
txt_Edit1.setHintTextColor(color.black);
txt_Edit1.setTextColor(color.holo_green_light);

2.2 Button / Image Button

One of the most important controlis Button / Image Button that represents an action to receive user action

<Button
            android:id="@+id/Button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/ButtonSubmit" >
        </Button>

<ImageButton
            android:id="@+id/ImageButton"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/ic_launcher" /> // set the src of the image

Or you can access from code as below

Button btn = (Button) findViewById(R.id.Button);
btn.setText("Click Here");

ImageButton img_btn = (ImageButton) findViewById(R.id.ImageButton);
img_btn.setImageResource(R.drawable.ic_launcher);

2.3 CheckBox

CheckBox are useful in case of multiple options, and it doesn't have alot of options,only set checked to true/false 

<CheckBox 
        android:id="@+id/CheckBox"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:checked="true"/>


//Or through Code
CheckBox chk =(CheckBox)findViewById(R.id.CheckBox);
chk.setChecked(true);

2.4 Radio Button / Radio Group

You can set a Radio Group which is a collection of Radio Buttons as example bellow

<RadioGroup
        android:id="@+id/RGroup"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:dividerPadding="1dp" > //Set a padding between each Radio Button vertically

        <RadioButton
            android:id="@+id/RGroup1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:checked="false" /> //by default it's set to false

        <RadioButton
            android:id="@+id/RGroup2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:checked="true" />
    </RadioGroup>

Summary

90% of your android applications will need the discussed Layouts and Controls. Hopefully, we discussed how to add a control and access it from your code , as well as choosing the best layout that fits your needs.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

Ahmed Alaa El-Din
Software Developer Enozom Software Company http://enozom.com/enozom/
Egypt Egypt
No Biography provided

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Questionhelp Pin
Member 114227122-Feb-15 23:40
memberMember 114227122-Feb-15 23:40 
AnswerRe: help Pin
Ahmed Alaa El-Din3-Feb-15 0:31
memberAhmed Alaa El-Din3-Feb-15 0:31 
GeneralThanks for the entry! Pin
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staffKevin Priddle27-Aug-14 7:21 
GeneralRe: Thanks for the entry! Pin
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memberAhmed Alaa El-Din28-Aug-14 11:51 
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QuestionThanks Message Pin
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AnswerRe: Thanks Message Pin
Ahmed Alaa El-Din12-Aug-14 7:45
memberAhmed Alaa El-Din12-Aug-14 7:45 

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