Collection类型不是通用的;它不能用参数<？参数化延伸E>

Question

I have a strange problem with Eclipse Galileo.
I set Java 1.6 as my JRE. On this line of code

List templates = new ArrayList ();

I see the following error in Eclipse's problem list:

The type Collection is not generic; it cannot be parameterized with arguments

I don't have any problems with building this project with Ant.
How can I fix it? Looks like it is an Eclipse problem, but because of this error, I can't compile/publish my project from the IDE.

Answer 1

What List are you importing? (see this thread from 2006 )

java.awt.List or java.util.List ?

Because, as eclipse aptly comments, java.awt.List is not parameterized ;)

---

Check also the

• Java Build path : it must not contain a reference to the J2SE 1.4.2 libraries.
• Source Compatibility : project properties -> Java Compiler Settings, Source Compatibility 5.0 or 6.0.

---

Other than that, there was lots of issue back in 2005 when the latest Eclipse 3.1 beta was supporting J2SE5, but this was fixed since then.

Try tyo use the latest JDK6 in your project.

Answer 2

It's late but still replying, might be helpful for others who are still facing the issue. I was getting exactly the same issue. The List was proper with util.List. The solution was to order the exports of the libraries. If you are using Maven or any other Libraries :

In Project -> Build Path -> Configure Build Path -> Order & Exports

Check 'JRE System Libraries' should be above 'Maven Dependencies'

This worked for me.

Answer 3

For those, who will get there from Google: the problem was with cryptix library. When I removed it from java build path the project is compiled sucesfully.

Answer 4

Did you name your class list? ie:

import java.util.*;

public class List {   // can't do this, name this something else.

    public static void main(String[] args) {
        List<Integer> l = new ArrayList<Integer>();

    }

}

Answer 5

Hey, I removed the cryptic library and it didn't work. But then I put JRE System Library at the top, and it worked. Really weird.

Answer 6

for example:

public class AClass<T extends Object>
{
 public HashMap<String, String> myMap;
}

if I write:

public class BClass
{

private AClass aClass = new AClass();

public void test()
{

aClass.get("test");
//return Object class

}

}

but if I write:

public class BClass
{

private AClass<?,?> aClass = new AClass<?,?>();

public void test()
{

aClass.get("test");
//return String class

}

}

Answer 7

Sometimes it's an eclipse hiccup and eclipse -clean plus refreshing all projects helps.

Edit

Does it change anything when you replace your code with:

java.util.List templates = new java.util.ArrayList();

or even

java.util.List<Object> templates = new java.util.ArrayList<Object>();

?

Answer 8

将条目“JRE System Library ...”放在项目，属性，java构建路径，顺序和导出的顶部

Answer 9

I changed the import

   import javax.swing.text.html.HTMLDocument.Iterator;

to

   import java.util.Iterator;

then it worked for me

Answer 10

use "import java.util.List"

instead of default import "import antlr.collections.List;"

and use the JRE5 or above for generic support of collection API....

Answer 11

Try to remove import antlr.collections.List; and click Ctr + space to use java.util

Answer 12

Some ideas:

• check the JRE library being used in your project (check the package explorer).
• check the installed JREs in the eclipse settings (same as used by ant).
• comment out the line just to check if it really is the error cause.
• retype the whole line from scratch.
• install a new (clean) version of eclipse, in a new folder (testing).

Answer 13

make java buildpath reference to greater than or equal to java 1.5

or you try to add the "import java.util.List" statement then you can see that

eclipse is saying it is conflicting with some other List type

for example it may be conflicting with com.lowagie.xx.xxx.List etc try to avoid these import

statements