Essential tools to manage import statements in Eclipse

It’s a big hassle to manually organise package import statements so it’s important to know what tools are available so your IDE can handle imports as quickly and quietly as possible.

Adding import statements for missing references and removing unused imports can take ages and the list of imports can get very long and hard to manage. As an example, the import statements below can consist of static/normal imports and wildcard/class imports:

// The list of imports can get really long...
import static org.junit.Assert.assertEquals; // Static imports
import java.util.List;
import java.util.ArrayList;
import org.apache.commons.lang.*; // Wildcard; unused so should be removed
...
public class MyTest {
   @Test
   public void testSomething() throws Exception {
      List<String> messages = new ArrayList<String>();
      assertEquals(1, 1);
   }
}

To make life easier, Eclipse has a heap of features that automatically manage import statements, including organising them when you save or when you press a keyboard shortcut. It can even deal with static imports. This tip covers some of these features, starting with the absolute essentials that save loads of time and moving on to more optional features that will depend on your environment and tastes.

Disable Eclipse formatting for certain sections of code only

In a previous tip, I showed how to automatically format code every time you save in Eclipse or how to manually format by pressing Ctrl+Shift+F. These work great most of the times but sometimes you want to exclude a certain block of code from formatting, often because the formatting turns out unreadable (ie. ugly) for that particular piece of code.

Eclipse allows you to disable formatting for a certain block or section of code by surrounding that code with formatter comments, known as Off/On tags. And you can also make generating those comments around a block of code extremely simple by creating a simple template.

Generate static imports in Eclipse on autocomplete for JUnit Assert, StringUtils and others

Eclipse normally adds import statements for you when you autocomplete a type, press Ctrl+Shift+O or organise imports when you save. However, by default it doesn’t do the same for static imports, something you’ll miss when using classes like JUnit’s Assert and Apache Commons’ StringUtils. This means having to add import statements manually, which takes unnecessary time.

So, in the code below, I want to be able to autocomplete assertEquals (line 7) and have Eclipse add a static import for org.junit.Assert.assertEquals (line 1).

import static org.junit.Assert.assertEquals;
...
public class MyTest {
   @Test
   public void testSomething() throws Exception {
      assertEquals(1, 1);
   }

Now, the good news is that there is a way to automatically add static imports when you use autocomplete. It’s done via a preference that tells Eclipse which static classes you want to include for Content Assist (autocomplete). I show you how to do this below.

The bad news is that there doesn’t seem to be a way to tell the Organise Imports command to add static imports. However, a working autocomplete should already cater for 90% of your coding needs, so the bad news isn’t that bad.

Automatically format and cleanup code every time you save

Eclipse has a wonderful feature that formats according to your coding standards. It handles things like indentation, where curly braces are placed, if blank lines should occur between field declaration and hundreds of other options.

However, to invoke this formatting, you have to tell Eclipse to do this every time you’ve edited the code. You can do this using Ctrl+Shift+F but (1) you have to do that every time and (2) you have to remember to do it in the first place (and we all know how good developers are at remembering things).

Eclipse sports a feature called Save Actions that makes formatting code easy. With this feature enabled, every time you save the file, Eclipse formats the code to your formatting preferences and does some cleanup of the code (eg. remove unused imports). All done automatically and for free.