Unable to execute DEX: NULL

The project is imported from external to eclipse. Once compiled, the following error occurs: conversion to Dalvik format failed: unable to execute DEX: null.
At the same time, eclipse is also very slow and has been suspended several times. Please give me some advice. Thank you.

Solution

1: Set memory

Eclipse.exe shortcut -- Right-click the shortcut menu and enter the following content in the target:
"D:/Eclipse/eclipse.exe"-vmargs-xms128m-xmx512m-XX: permsize = 64 m-XX: maxpermsize = 128 m

The installation path of eclipse is enclosed in double quotation marks.

If 1 fails:

Import the database as a user library. The procedure is as follows:

1. Right-click the project in eclipse and select "build path-> Add libraries ...".
2. Select User library from the list and click Next.
3. Click the "user libraries..." button.
4. Click "new..." in the user libraries dialog.
5. Give the user library a name and select the system library checkbox and click OK.
6. Highlight the newly added user library in the list and click the "add jars..." button and add the desired jar files.
7. Click OK on the user libraries dialog.
8. Make sure the new user library is checked in the Add library dialog and

Use my own project. Compile OK.

If there is still a Red Cross, select Java build path -- "order and export to put the imported package in front of the android package.