Eclipse错误：java.lang.CharSequence无法解析 [英] Eclipse Error: java.lang.CharSequence cannot be resolved

问题描述

我试图在Eclipse中编译一个简单的代码时遇到错误。我正在使用jre8。

例如，当我尝试编译这段代码：

  import java.util.ArrayList; 
 import java.util.Collections; 
 import java.util.List; 
 
 public class MyProject {
 public static void main（String args []）
 {
列表< String> myList = new ArrayList< String>（）; 
 
 myList.add（test）; 
 myList.add（test2）; 
 
 Collections.sort（myList）; 
} 
} 
  

我在 Collections.sort（myList）; 行。

错误是：

 线程main中的异常java.lang.Error：未解决的编译问题：
无法解析类型java.lang.CharSequence。它是间接引用的.class文件
 
在project.Principal.main（Principal.java:14）
  

我已经打开eclipse Build Path，删除了JRE System Library [jre8]并再次添加。但没有工作！我能做什么？谢谢！

PS .:在 Collections.sort（myList）; 行eclipse显示此错误： p>

无法解析java.lang.CharSequence类型。

解决方案

确保您的Eclipse IDE支持Java 8： h1>

支持Java 8的第一个Eclipse版本是Eclipse Kepler SR2（4.3.2），还有一个补丁。 （见：

I'm getting a error trying to compile a simple code in Eclipse. I'm using jre8.

For example, when I try to compile this code:

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class MyProject {
    public static void main (String args[])
    {
        List<String> myList = new ArrayList<String>();

        myList.add("test");
        myList.add("test2");

        Collections.sort(myList);
    }
}

I get a error in the Collections.sort(myList); line.

The error is:

Exception in thread "main" java.lang.Error: Unresolved compilation problem: 
    The type java.lang.CharSequence cannot be resolved. It is indirectly referenced from required .class files

    at project.Principal.main(Principal.java:14)

I have already opened eclipse Build Path, removed JRE System Library [jre8] and added it again. But didn't work! What can I do? Thanks!

PS.: In the Collections.sort(myList); line eclipse shows this error:

The type java.lang.CharSequence cannot be resolved. It is inderectly referenced from required .class files.

解决方案

Ensure that your Eclipse IDE supports Java 8:

The first Eclipse version supporting Java 8 was Eclipse Kepler SR2 (4.3.2) with an additional patch. (See: Installing Java™ 8 Support in Eclipse Kepler SR2, and the corresponding Marketplace Item that needs to be installed: Java 8 support for Eclipse Kepler SR2).

In my opinion you should udpate to the latest Eclipse Version.

With Luna SR2 (4.4.2) no additional patch is necessary.

---

Ensure the 1.8 JRE is available in your Workspace:

Windows > Preferences: Java > Installed JREs

If this is not the case you can add a new JRE with the add button.

---

Ensure that JRE System Library == JavaSE-1.8 for your Project

In the Package Explorer, you should see the Java version:

If this is not correct you should open the context menu the JRE System Library item and select the Properties menu entry.

In your project you have a .classpath file (Use the Navigator View if you do not see the file), that should looks like this:

<?xml version="1.0" encoding="UTF-8"?>
<classpath>
    <classpathentry kind="src" path="src"/>
    <classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.8"/>
    <classpathentry kind="output" path="bin"/>
</classpath>

---

Rebuild your project

Project Menu > Clean...

Select your project from the list or "Clean all projects" and "Start a build immediately"

---

See also:

• Explaination from @mkrakhin in his answer: The type java.lang.CharSequence cannot be resolved in package declaration

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