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POjava beginner calculator not compiling
 

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  1. POjava beginner calculator not compiling
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    <p>I am a java beginner and I've just made my first calculator but it is not compiling. It is showing some problems during compilation, at <code>frame.setPreferredSize(new Dimension(200, 250));</code> and <code>frame.setDefaultCloserOperation(JFrame.EXIT_ON_CLOSE):</code> These errors are being shown as <code>&lt;identifier&gt; expected</code> and <code>illegal start of expression</code>. What is the problem?</p> <pre><code>import java.sql.*; import javax.swing.*; import javax.swing.event.*; import java.awt.event.*; import java.awt.*; public class Cal extends JFrame implements ActionListener { JFrame frame = new JFrame(); frame.setPreferredSize(new Dimension(200, 250)); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); public Cal(){ Button btn_1 = new Button("1"); btn_1.setSize(5, 5); Button btn_2 = new Button("2"); btn_2.setSize(5, 5); Button btn_3 = new Button("3"); btn_3.setSize(5, 5); Button btn_4 = new Button("4"); btn_4.setSize(5, 5); Button btn_5 = new Button("5"); btn_5.setSize(5, 5); Button btn_6 = new Button("6"); btn_6.setSize(5, 5); Button btn_7 = new Button("7"); btn_7.setSize(5, 5); Button btn_8 = new Button("8"); btn_8.setSize(5, 5); Button btn_9 = new Button("9"); btn_9.setSize(5, 5); Button btn_0 = new Button("0"); btn_0.setSize(5, 5); Button btn_dot = new Button("."); btn_dot.setSize(5, 5); Button btn_div = new Button("/"); btn_div.setSize(5, 5); Button btn_mult = new Button("*"); btn_mult.setSize(5, 5); Button btn_sub = new Button("-"); btn_sub.setSize(5, 5); Button btn_addd = new Button("+"); btn_addd.setSize(5, 5); Button btn_equ = new Button("="); btn_equ.setSize(5, 5); JTextField jt = new JTextField(); jt.setHorizontalAlignment(JTextField.RIGHT); jt.setEditable(false); double fnum, snum, total; String op = null; JPanel players = new JPanel(); players.setLayout(new GridLayout(1, 1)); players.add(jt, BorderLayout.NORTH); players.setPreferredSize(new Dimension(10, 50)); JPanel players1 = new JPanel(new GridLayout(4, 3)); // adding buttons players1.add(btn_7); players1.add(btn_8); players1.add(btn_9); players1.add(btn_div); players1.add(btn_4); players1.add(btn_5); players1.add(btn_6); players1.add(btn_mult); players1.add(btn_1); players1.add(btn_2); players1.add(btn_3); players1.add(btn_sub); players1.add(btn_0); players1.add(btn_dot); players1.add(btn_equ); players1.add(btn_addd); players1.setPreferredSize(new Dimension(150, 150)); </code></pre> <p>//applying actionlistener</p> <pre><code>btn_1.addActionListener(this); btn_2.addActionListener(this); btn_3.addActionListener(this); btn_4.addActionListener(this); btn_5.addActionListener(this); btn_6.addActionListener(this); btn_7.addActionListener(this); btn_8.addActionListener(this); btn_9.addActionListener(this); btn_0.addActionListener(this); btn_dot.addActionListener(this); btn_addd.addActionListener(this); btn_mult.addActionListener(this); btn_div.addActionListener(this); btn_sub.addActionListener(this); btn_equ.addActionListener(this); </code></pre> <p>//setting contents to be available</p> <pre><code>JPanel content = new JPanel(); content.setLayout(new BorderLayout()); frame.setContentPane(content); content.add(players, BorderLayout.NORTH); content.add(players1, BorderLayout.SOUTH); frame.setTitle("Calculator"); frame.pack(); frame.setVisible(true); } </code></pre> <p>//applying actions to be performed</p> <pre><code> public void actionPerformed(ActionListener e){ String input = jt.getText(); if(e.getSource()==btn_1) {jt.setText(input + "1");} else if(e.getSource()==btn_2) {jt.setText(input + "2");} else if(e.getSource()==btn_3) {jt.setText(input + "3");} else if(e.getSource()==btn_4) {jt.setText(input + "4");} else if(e.getSource()==btn_5) {jt.setText(input + "5");} else if(e.getSource()==btn_6) {jt.setText(input + "6");} else if(e.getSource()==btn_7) {jt.setText(input + "7");} else if(e.getSource()==btn_8) {jt.setText(input + "8");} else if(e.getSource()==btn_9) {jt.setText(input + "9");} else if(e.getSource()==btn_0) {jt.setText(input + "0");} else if(e.getSource()==btn_dot) {jt.setText(input + ".");} else if(e.getSource()==btn_addd) { fnum = Double.parseDouble(jt.getText()); op = "+"; jt.setText(" "); } else if(e.getSource()==btn_sub) { fnum = Double.parseDouble(jt.getText()); op = "-"; jt.setText(" "); } else if(e.getSource()==btn_div) { fnum = Double.parseDouble(jt.getText()); op = "/"; jt.setText(" "); } else if(e.getSource()==btn_equ) { snum = Double.parseDouble(jt.getText()); if(op.equ("+")) { total = fnum + snum; } if(op.equ("-")) { total = fnum - snum; } if(op.equ("*")) { total = fnum * snum; } if(op.equ("/")) { total = fnum / snum; } jt.setText(" " + total); } } public static void main(String args[]){ Cal obj = new Cal(); } } </code></pre>
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