While testing different applications you will get to the need of testing the following scenario:

The user is opening the application, clicks the Overview button which sends the application
to background and reopens the application by choosing it from the recent used application.

To be able to do that you need to know how to implement two important actions:
1. Click the Overview button which send the application to background; for doing this you can use the following
code snippet written in Java:

    public void clickOverviewButton(){
		((AndroidDriver<WebElement>)driver).pressKeyCode(AndroidKeyCode.KEYCODE_APP_SWITCH);
	}

2. Reopen the application from the recent applications; for doing this you can use the application name like in the following example written in Java:

    public void clickRecentAppByText(String appText){
		waitForElementByText(appText, 10);
		driver.findElement(By.xpath("//*[@text=\"" + appText + "\"]")).click();
	}

Hope this helps with your daily testing tasks. Details on how to use the Overview, Home and Back buttons in Appium for Android