web项打包报错 could not find the main class: org.eclipse.ant.internal.launching.remote.InternalAntRunner.

Could not find the main class: org.eclipse.ant.internal.launching.remote.InternalAntRunner. 最近更新了eclipse，发现运行ant不好使来了，报的异常如标题所示。JRE应该选择Run in the same JRE as the workspace

The solution is to go to Run as → External tools configuration… → JRE where the default was set to “Separate JDK”: jdk1.6.0_31 (I had set up JDKs 6-8 in Preferences after installing). I changed this to “run in the same JRE as the workspace” and now it works.
Bug fix would be to provide a working default configuration with setup. Configuration should be in a way it does not break if the user adds additional JDKs to Preferences.