Fwd: gcj can not import packages

Wed Nov 9 11:29:00 GMT 2016

Can someone help me to understand why gcj can not import packages
while javac can? Any CLASSPATH setting required?
[user5@FOO-51 tmp]$ gcj -v
Using built-in specs.
Reading specs from
/usr/local/lib/gcc/x86_64-unknown-linux-gnu/4.9.0/../../../libgcj.spec
rename spec startfile to startfileorig
rename spec lib to liborig
COLLECT_GCC=gcj
COLLECT_LTO_WRAPPER=/usr/local/libexec/gcc/x86_64-unknown-linux-gnu/4.9.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ./configure --with-java-home=/usr/jdk1.8.0_111/jre/
--with-ecj-jar=/usr/share/java/eclipse-ecj.jar
Thread model: posix
gcc version 4.9.0 (GCC)
[user5@FOO-51 tmp]$
[user5@FOO-51 tmp]$
[user5@FOO-51 tmp]$
[user5@FOO-51 tmp]$ cat HelloWorld.java
import java.util.Objects;
import java.nio.file.*;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.CompletionStage;
public class HelloWorld {
 public static void main (String[] args) {
 System.out.println ("Hello World!");
 }
}
[user5@FOO-51 tmp]$
[user5@FOO-51 tmp]$ echo $CLASSPATH
[user5@FOO-51 tmp]$
[user5@FOO-51 tmp]$
[user5@FOO-51 tmp]$ javac -version
javac 1.8.0_111
[user5@FOO-51 tmp]$ javac HelloWorld.java
[user5@FOO-51 tmp]$ java HelloWorld
Hello World!
[user5@FOO-51 tmp]$
[user5@FOO-51 tmp]$ gcj --main=HelloWorld HelloWorld.class
[user5@FOO-51 tmp]$ ./a.out
Hello World!
[user5@FOO-51 tmp]$
[user5@FOO-51 tmp]$ gcj --main=HelloWorld HelloWorld.java
HelloWorld.java:1: error: The import java.util.Objects cannot be resolved
 import java.util.Objects;
 ^^^^^^^^^^^^^^^^^
HelloWorld.java:2: error: The import java.nio.file cannot be resolved
 import java.nio.file.*;
 ^^^^^^^^^^^^^
HelloWorld.java:3: error: The import
java.util.concurrent.CompletableFuture cannot be resolved
 import java.util.concurrent.CompletableFuture;
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
HelloWorld.java:4: error: The import
java.util.concurrent.CompletionStage cannot be resolved
 import java.util.concurrent.CompletionStage;
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
4 problems (4 errors)
[user5@FOO-51 tmp]$