Android Tutorials : Basic widgets
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The document discusses various Android widgets such as TextView, ImageView, EditText, CheckBox, and RadioButton. It provides code examples for how to implement each widget in an Android application. For TextView, it demonstrates how to display simple text. For ImageView, it shows how to display an image. For EditText, it explains how to create an editable text field. For CheckBox, it provides an example of a checkbox that can be checked or unchecked. And for RadioButton, it discusses using radio buttons within a RadioGroup so that only one can be selected at a time.
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Android Tutorials : Basic widgets
- 1. Android.Widgets Tutorial 1 : Empowering Android Widgets By: Mr.PrajyotMainkar MS Software Systems( BITS-Pilani) BE(Hons.) Computer Engineering , PMP( IIT Delhi) S
- 2. TextView – The Andro-Label The simplest widget is the label, referred to in Android as a TextView . Typically, these are used like labels in Android UI Create a new android project with following contents in main.xml and run this project on emulator <?xml version="1.0" encoding="utf-8"?> <TextViewxmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="This is sample demo of TextView" />
- 3. TextView – The Andro-Label The following output is obtained when you run the code via emulator.
- 4. Images – Fleeting with images Android has two widgets to help embed images in your activities: ImageViewand ImageButton. As the names suggest, they are image-based analogues to TextView and Button , respectively. <?xml version="1.0" encoding="utf-8"?> <ImageViewxmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/icon" android:layout_width="fill_parent" android:layout_height="fill_parent" android:adjustViewBounds="true" android:src="@drawable/logo" /> Note that, android:src takes path of image from the drawable folder(@ is the reference), so drag „n drop /paste any logo.png image to drawable folder.
- 5. Images – Fleeting with images The following output is obtained when you run the code via emulator.
- 6. EditText– Learning EditText EditText is a thin veneer over TextView that configures itself to be editable. In the java file (Src folder) import the file “import android.widget.EditText;”. Find the xml code below <?xml version="1.0" encoding="utf-8"?> <EditTextxmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/editfield" android:layout_width="fill_parent" android:layout_height="fill_parent" android:singleLine="false" />
- 7. EditText – Learning EditText package com.EditTextDemo; import android.app.Activity; import android.os.Bundle; import android.widget.EditText; public class EditTextDemoActivity extends Activity { /** Called when the activity is first created. */ @Override EditText E; public void onCreate(BundlesavedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); E.setText("This is sample edit text demo"); } }
- 8. CheckBox– Lets *Check* •isChecked(): Determines if the check box has been checked. •setChecked(): Forces the check box into a checked or unchecked •state. •toggle(): Toggles the check box as if the user checked it. <?xml version="1.0" encoding="utf-8"?> <CheckBoxxmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/checkbox" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="This checkbox is unchecked" />
- 9. CheckBox – Lets *Check* package com.CheckBoxDemo; import android.app.Activity; import android.os.Bundle; import android.widget.CheckBox; import android.widget.CompoundButton; public class CheckBoxDemoActivity extends Activity implements CompoundButton.OnCheckedChangeListener { CheckBox checkbox; public void onCreate(BundlesavedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); checkbox=(CheckBox)findViewById(R.id.checkbox); checkbox.setOnCheckedChangeListener(this); } public void onCheckedChanged(CompoundButtonbuttonView, booleanisChecked) { if (isChecked) { checkbox.setText("This checkbox is: checked"); } else { checkbox.setText("This checkbox is: unchecked"); } } }
- 10. CheckBox – Lets *Check* The following output is obtained when you run the code via emulator.
- 11. RadioButton – Tune Up •check(): Checks a specific radio button via its ID •clearCheck(): Clears all radio buttons, so none in the group are checked. •getCheckedRadioButtonId(): Gets the ID of the currently checked radio button (or -1 if none are checked). Most times RadioButton widgets are placed inside a RadioGroup . The RadioGroup indicates a set of radio buttons whose state is tied, meaning only one button in that group can be selected at any time. If you assign an android:id to your RadioGroup in your XML layout, you can access the group from your Java code and
- 12. RadioButton – Tune Up •The XML Code is below. Make no changes to Java File : <?xml version="1.0" encoding="utf-8"?> <RadioGroup xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" > <RadioButton android:id="@+id/radio1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Goa" /> <RadioButton android:id="@+id/radio2" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Maharashtra" /> <RadioButton android:id="@+id/radio3" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Kerala" /> </RadioGroup>
- 13. Thank you.. GET IN TOUCH– Tune Up RadioButton Phone: +91-9822987513 facebook.com/prajyotmainkar Email: twitter.com/prajyotm prajyotm@msn.com