how to use operators while making calc in java <p>i used this code and I am having problem in the very basic step of how to use operator. Moreover I am even having problem taking more then 1 digit. If you please just add up the missing statements which would help me out. In the given code I have removed those steps that created problems in <code>actionPerformed</code> function</p> <pre><code>import java.awt.*; import javax.swing.*; import java.awt.event.*; import javax.swing.event.*; public class calculator1 implements ActionListener { private JFrame f; private JButton a,a1,a2,a3,a4,a5,a6,a7,a8,a9,a10,a11,a12,a13,a14,a15; JTextField tf; String msg=""; public calculator1() { f=new JFrame("Calculator"); f.setLayout(null); a=new JButton("1"); a.setActionCommand("1"); a1=new JButton("2"); a1.setActionCommand("2"); a2=new JButton("3"); a2.setActionCommand("3"); a3=new JButton("4"); a3.setActionCommand("4"); a4=new JButton("5"); a4.setActionCommand("5"); a5=new JButton("6"); a5.setActionCommand("6"); a6=new JButton("7"); a6.setActionCommand("7"); a7=new JButton("8"); a7.setActionCommand("8"); a8=new JButton("9"); a8.setActionCommand("9"); a9=new JButton("0"); a9.setActionCommand("0"); a10=new JButton("+"); a10.setActionCommand("+"); a11=new JButton("-"); a11.setActionCommand("-"); a12=new JButton("*"); a12.setActionCommand("*"); a13=new JButton("/"); a13.setActionCommand("/"); a14=new JButton("="); a14.setActionCommand("="); a15=new JButton("00"); a15.setActionCommand("00"); tf= new JTextField(30); } public void launchframe() { f.setSize(500,600); a.setBounds(100,200,50,50); a.addActionListener(this); a1.setBounds(160,200,50,50); a1.addActionListener(this); a2.setBounds(220,200,50,50); a2.addActionListener(this); a3.setBounds(100,300,50,50); a3.addActionListener(this); a4.setBounds(160,300,50,50); a4.addActionListener(this); a5.setBounds(220,300,50,50); a5.addActionListener(this); a6.setBounds(100,400,50,50); a6.addActionListener(this); a7.setBounds(160,400,50,50); a7.addActionListener(this); a8.setBounds(220,400,50,50); a8.addActionListener(this); a9.setBounds(100,500,50,50); a9.addActionListener(this); a10.setBounds(300,200,50,50); a10.addActionListener(this); a11.setBounds(300,300,50,50); a11.addActionListener(this); a12.setBounds(300,400,50,50); a12.addActionListener(this); a13.setBounds(300,500,50,50); a13.addActionListener(this); a14.setBounds(160,500,50,50); a14.addActionListener(this); a15.setBounds(220,500,50,50); a15.addActionListener(this); f.add(a); f.add(a1); f.add(a2); f.add(a3); f.add(a4); f.add(a5); f.add(a6); f.add(a7); f.add(a8); f.add(a9); f.add(a10); f.add(a11); f.add(a12); f.add(a13); f.add(a14); f.add(a15); tf.setBounds(100,150,250,30); f.add(tf); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); f.setVisible(true); } public void actionPerformed(ActionEvent ae) { String s=ae.getActionCommand(); tf.setText(s); } public static void main(String[]arg) { calculator1 c1=new calculator1(); c1.launchframe(); } } </code></pre>