Help me to remove the error in my program ????
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
class math
{
	JFrame jf;
	JTextField jt;
	JButton jb;
	JButton jb1;
	math()
	{
		jf=new JFrame("frame");
		jf.setSize(200,200);
		jf.setVisible(true);
		jt=new JTextField(50);
		jf.setLayout(new FlowLayout());
		JButton jb=new JButton("30");
		JButton jb1=new JButton("sin");
		jb.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent ae)
			{
				jt.setText("30");
			}
		});
		jb1.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent ae)
			{
				String s=jt.getText();
				double x=Double.parseDouble(s);
				double s1=Math.sin(x);
				jt.setText(s1);
			}
		});
		JButton jb2=new JButton("cos");
		jf.add(jt);
		jf.add(jb);
		jf.add(jb1);
		jf.add(jb2);
	}
	public static void main(String args[])
	{
		new math();
	}
}
//its giving error that double can't be applied to jt.setText
Help me to remove the error in my program ????
===

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
class math
{
	JFrame jf;
	JTextField jt;
	JButton jb;
	JButton jb1;
	math()
	{
		jf=new JFrame("frame");
		jf.setSize(200,200);
		jf.setVisible(true);
		jt=new JTextField(50);
		jf.setLayout(new FlowLayout());
		JButton jb=new JButton("30");
		JButton jb1=new JButton("sin");
		jb.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent ae)
			{
				jt.setText("30");
			}
		});
		jb1.addActionListener(new ActionListener()
		{
			public void actionPerformed(ActionEvent ae)
			{
				String s=jt.getText();
				double x=Double.parseDouble(s);
				double s1=Math.sin(x);
				jt.setText(s1);
			}
		});
		JButton jb2=new JButton("cos");
		jf.add(jt);
		jf.add(jb);
		jf.add(jb1);
		jf.add(jb2);
	}
	public static void main(String args[])
	{
		new math();
	}
}
//its giving error that double can't be applied to jt.setText