popup menu in eclipse plugin development - eclipse-plugin

Question

I want to create plugin in which if user right click on any folder or file, the popup menu will open and there is option to read file.
As I am new to plugin development have done some code. My plugin.xml is following
<?xml version="1.0" encoding="UTF-8"?>
<?eclipse version="3.4"?>
<plugin>
<extension
point="org.eclipse.ui.commands">
<category
name="Sample Category"
id="com_.samsung.plugin.second.commands.category">
</category>
<command
name="Sample Command"
categoryId="com_.samsung.plugin.second.commands.category"
id="com_.samsung.plugin.second.commands.sampleCommand">
</command>
<command
defaultHandler="com .samsung.plugin.second.SampleHandler"
id="com .samsung.plugin.second.Sample"
name="name">
</command>
</extension>
<extension
point="org.eclipse.ui.handlers">
<handler
commandId="com_.samsung.plugin.second.commands.sampleCommand"
class="com_.samsung.plugin.second.handlers.SampleHandler">
</handler>
</extension>
<extension
point="org.eclipse.ui.bindings">
<key
commandId="com_.samsung.plugin.second.commands.sampleCommand"
contextId="org.eclipse.ui.contexts.window"
sequence="M1+6"
schemeId="org.eclipse.ui.defaultAcceleratorConfiguration">
</key>
</extension>
<extension
point="org.eclipse.ui.menus">
<menuContribution
locationURI="popup:org.eclipse.jdt.ui.PackageExplorer">
<command commandId="com_.samsung.plugin.second"
label="Read File" style="push">
</command>
</menuContribution>
</extension>
<extension point="org.eclipse.ui.commands">
<command defaultHandler="com_.samsung.plugin.second.handler.SampleHandler"
id="com_.samsung.plugin.second" name="Convert">
</command>
</extension>
</plugin>
and i have a SampleHandler class in com_.samsung.plugin.second.handlers;
but in popup Readfile option is not visible.
please suggest me whats wrong with this.
any help will be appriciated.
Thanks