[java] Import XXX cannot be resolved for Java SE standard classes

I use Eclipse and turns out I have a bunch of import * not resolved errors.

import java.sql.Date;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.sql.Timestamp;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

All of the above have the same error. I checked my java version it is 1.7.0 open jdk. I updated Java Home and the JRE library to use. Its still not working. Note: I imported the code repository from bibucket via the mercurial plugin itself.

This is an issue relating JRE.In my case (eclipse Luna with Maven plugin, JDK 7) I solved this by making following change in pom.xml and then Maven Update Project.

from:

 <configuration>
        <source>1.8</source>
        <target>1.8</target>
</configuration>

to:

 <configuration>
        <source>1.7</source>
        <target>1.7</target>
</configuration>

Screenshot showing problem in JRE:

If by chance you have deleted JRE SYSTEM LIBRARY, then go to your JRE installation and add jars from there.

Eg:- C:\Program Files (x86)\Java\jre7\lib ---add jars from here

C:\Program Files (x86)\Java\jre7\lib\ext ---add jars from here

If the project is Maven, you can try this way :

1. right click the "Maven Dependencies"-->"Build Path"-->"Remove from the build path";
2. right click the project ,navigate to "Maven"--->"Update project....";

Then the import issue should be solved .