Introduction: HelloWorld With Exit Button AndroidStudio
This tutorial will teach you on how to build Android App that display Hello World text and Exit button to exit from the activity.
Step 1: Create New Project
Open Android Studio and create new project. Name your new project as HelloWorld and add Empty Activity.
Step 2: Edit the Activity_main.xml
Add a new text view and button (as shown below) inside the res>layout>activity_main.xml.
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:foregroundGravity="center"
android:gravity="center"
android:text="Hello World!"
android:textColor="@color/black"
android:textSize="30sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
android:id="@+id/textView" />
<Button
android:id="@+id/btn_logout"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/textView"
android:layout_centerHorizontal="true"
android:text="Exit"
android:textColor="@color/black"/>
Since we using colors for the text, add a new resource in the color.xml. Go to res>values>colors.xml and add the following code
<resources> <color name="black">#0d0c0c> <resources/>
Step 3: Now, Edit the MainActivity.java
Add the following code to the OnCreate() method in the MainActivity.java
We add OnClickListener function to the button so whenever user clicked on the button a dialog will popup with a warning "Do you want to exit?". Two options will be provided to the user, "Yes ..." to exit and "Not ..." to close the dialog and go back to main.
Button btnlogout = (Button) findViewById(R.id.btn_logout);
btnlogout.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
final AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
builder.setTitle("Exit");
builder.setMessage("Do you want to exit ??");
builder.setPositiveButton("Yes. Exit now!", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i)
finish();
}
});
builder.setNegativeButton("Not now", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i)
dialogInterface.dismiss();
}
});
AlertDialog dialog = builder.create();
dialog.show();
}
});