在用idea軟件run的時候顯示：
（objc[23229]: Class JavaLaunchHelper is implemented in both /Library/Java/JavaVirtualMachines/jdk1.7.0_80.jdk/Contents/Home/bin/java (0x10af154c0) and /Library/Java/JavaVirtualMachines/jdk1.7.0_80.jdk/Contents/Home/jre/lib/libinstrument.dylib (0x10afd04e0). One of the two will be used. Which one is undefined.）
解決辦法：
1.點擊IntelliJ IDEA最上面菜單的”Help”下的“Edit Custom Properties”，沒有這個properties文件的話，IntelliJ IDEA會提示創建;
2.在文件中加上
idea.no.launcher=true
3.重啟IntelliJ IDEA
原因分析：
You can find all the details here: IDEA-170117 “objc: Class JavaLaunchHelper is implemented in both …” warning in Run consoles It’s the old bug in Java on Mac that got triggered by the Java Agent being used by the IDE when starting the app. This message is harmless and is safe to ignore. Oracle developer’s comment: The message is benign, there is no negative impact from this problem since both copies of that class are identical (compiled from the exact same source). It is purely a cosmetic issue. The problem is fixed in Java 9 and in Java 8 update 152. If it annoys you or affects your apps in any way, the workaround for IntelliJ IDEA is to disable idea_rt launcher agent by adding idea.no.launcher=true into idea.properties (Help | Edit Custom Properties...).
Mac上面Java的一個老Bug了，會在那些使用了Java Agent的IDE上運行應用時觸發，但這個Error對程序是無影響的，可以無視