GridBagLayout being flagged as error
===

    import javax.swing.JFrame;
    import javax.swing.SwingUtilities;
    >>>import java.awt.GridBagLayout;
    import java.awt.GridBagConstraints;
    import javax.swing.JButton;
    import javax.swing.BorderFactory;
    public class GridBagLayout {
    	public static void createWindow(){
    		JFrame aWin = new JFrame("Title");
    		aWin.setBounds(0,0,200,200);
    		aWin.setVisible(true);
    		
    		GridBagLayout gridBag = new GridBagLayout();
    		GridBagConstraints constraints = new GridBagConstraints();
    		>>>aWin.getContentPane().setLayout(gridBag);
    
    		
    		constraints.weightx = constraints.weighty = 10.0;
    		constraints.fill = GridBagConstraints.BOTH;
    		addButton(" Press ",constraints,gridBag,aWin);
    		constraints.gridwidth=GridBagConstraints.REMAINDER;
    	}
    	static void addButton(String label,GridBagConstraints constraints,GridBagLayout layout,JFrame window){
    		JButton button = new JButton(label);
    		button.setBorder(BorderFactory.createEtchedBorder());
    		>>>layout.setConstraints(button,constraints);
    		window.getContentPane().add(button);
    	}
    	public static void main(String[] args){
    		SwingUtilities.invokeLater(new Runnable(){
    			public void run(){
    				createWindow();
    			}
    		});
    	}
    }

The lines marked with >>> are flagged as error by Eclipse IDE.  
The error for `import java.awt.GridBagLayout;` states that there is a possible conflict with the type within the same file  
The error for `aWin.getContentPane().setLayout(gridBag);` states that GridBagLayout can not be applied although when I tried FlowLayout, it was fine.  
The error for `layout.setConstraints(button,constraints);` states that the method is undefined.  
What is the cause for this error? Please help me solve it.