Upgrade Eclipse java compiler

Question

I started using Ant, that ships with Eclipse. It annoys me, that I get hundreds of warnings in the lines of:

[javac] warning: java\\io\\BufferedInputStream.class(java\\io:BufferedInputStream.class): major version 51 is newer than 50, the highest major version supported by this compiler.
[javac] It is recommended that the compiler be upgraded.

How do I upgrade compiler?

Answer 1

download and install newer version of JDK.

Windows - > Preference - > Java - > Installed JRE set newer version here

Answer 2

Major version 51 is Java 7 - looks like you're developing against a preview Java 7 API library but compiling with a Java 6 javac. Either make sure ant uses the Java 7 compiler, or use a Java 6 API library to compile against.

Answer 3

Thanks, I figured it out.

For those whom it may concern, to make sure Ant uses the Java 7 compiler:

Preferences -> Ant -> Runtime -> Classpath -> Global Entries

Click Add External Jars and put your tools.jar here.

It will look something like C:\\Program Files\\Java\\jdk1.7.0_03\\lib

Answer 4

您可能还需要考虑此StackOverflow问题的已接受答案： 在使用较旧的JDK库时将Eclipse ant降级为编译（Java 1.7 - > 1.6）

Answer 5

Follow these steps:

1. Download last JDK and install it.
2. Go to C:/Program files/Java and delete the previous JDK.
3. Update your JAVA_HOME and PATH Environment Variables with the new JDK.
4. Open Eclipse and in Windows > Preference > Java > Installed JRE, set newer version here

If there is a broken link with a jar in previous JDK, Eclipse will notify you. I solved in this way the problem with tools.jar ant reference, but it is a general way to find the solution.

Answer 6

由于我的开发环境应该基于Java 6，唯一有助于解决这个问题的就是删除Java 7

Answer 7

I solved my warning with answer from Bao. I had JDK1.6 installed before. Then installed JDK1.7 and ant was stil using JKD1.6 for compiling.

What I have changed is also set the JDK for the project: right click on project > properties > Java Build Path

If you have JDK1.6 here, try to change it to JDK1.7.

Answer 8

您可能还需要做的另一件事是进入“编辑配置”窗口的JRE选项卡并选择JRE版本。