An indeterminate ProgressBar shows a cyclic animation without an indication of progress.
Basic indeterminate ProgressBar (spinning wheel)
<ProgressBar
android:id="@+id/progressBar"
android:indeterminate="true"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
Horizontal indeterminate ProgressBar (flat bar)
<ProgressBar
android:id="@+id/progressBar"
android:indeterminate="true"
android:layout_width="match_parent"
android:layout_height="wrap_content"
style="@android:style/Widget.ProgressBar.Horizontal"/>
Other built-in ProgressBar styles
style="@android:style/Widget.ProgressBar.Small"
style="@android:style/Widget.ProgressBar.Large"
style="@android:style/Widget.ProgressBar.Inverse"
style="@android:style/Widget.ProgressBar.Small.Inverse"
style="@android:style/Widget.ProgressBar.Large.Inverse"
To use the indeterminate ProgressBar in an Activity
ProgressBar progressBar = (ProgressBar) findViewById(R.id.progressBar);
progressBar.setVisibility(View.VISIBLE);
progressBar.setVisibility(View.GONE);