Eclipse Cookbook

5.3. Starting a Debugging Session

Problem

Your code isn’t running as you want it to, and it’s time to debug.

Solution

Start a new debugging session with the items in the Run menu. Then use the various debugging options, such as single-stepping, setting breakpoints, and more.

Discussion

Say you want your code to display this output:

3...
2...
1...
Houston, we have liftoff.

Your first attempt at the code might look like that shown in Example 5-3, in the class DebugClass in an application named DebugApp.

Example 5-3. The DebugApp example

package org.cookbook.ch05;

public class DebugClass
{
    public static void main(String[] args)
    {
        for(int loopIndex = 3; loopIndex > 0; loopIndex--)
        {
            System.out.println(loopIndex + "...");
            if(loopIndex == 0)
            {
                System.out.println("Houston, we have liftoff.");
            }
        }
    }
}

Unfortunately, the code in Example 5-3 gives you this result:

3...
2...
1...

It’s time to debug. To start a debugging session, use one of the following items in the Run menu:

Run→ Debug History

Enables you to select a recently run project to debug

Run→ Debug As

Enables you to select the type of session to run (Java Applet, Java Applications, JUnit Test, or Run-time Workbench) from a submenu

Run→ Debug

Enables you to set the launch configuration for a debugging session

To start debugging the code in DebugApp, select Run→ Debug As→ Java Application, which opens and runs your code in the Debug perspective, as shown in Figure 5-8.

Figure 5-8. First attempt at debugging

Take a look at the Debug perspective in Figure ...