import java.awt.BorderLayout;
import java.awt.Button;
import java.awt.Container;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JApplet;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class PopupCalculatorApplet extends JApplet implements ActionListener {
  public void init() {
    Button calcButton = new Button("Calculator");
    calcButton.addActionListener(this);
    Container contentPane = getContentPane();
    contentPane.add(calcButton);
  }

  public void actionPerformed(ActionEvent evt) {
    if (calc.isVisible())
      calc.setVisible(false);
    else
      calc.show();
  }

  private JFrame calc = new CalculatorFrame();
}

class CalculatorPanel extends JPanel implements ActionListener {
  public CalculatorPanel() {
    setLayout(new BorderLayout());

    display = new JTextField("0");
    display.setEditable(false);
    add(display, "North");

    JPanel p = new JPanel();
    p.setLayout(new GridLayout(4, 4));
    String buttons = "789/456*123-0.=+";
    for (int i = 0; i < buttons.length(); i++)
      addButton(p, buttons.substring(i, i + 1));
    add(p, "Center");
  }

  private void addButton(Container c, String s) {
    JButton b = new JButton(s);
    c.add(b);
    b.addActionListener(this);
  }

  public void actionPerformed(ActionEvent evt) {
    String s = evt.getActionCommand();
    if ('0' <= s.charAt(0) && s.charAt(0) <= '9' || s.equals(".")) {
      if (start)
        display.setText(s);
      else
        display.setText(display.getText() + s);
      start = false;
    } else {
      if (start) {
        if (s.equals("-")) {
          display.setText(s);
          start = false;
        } else
          op = s;
      } else {
        calculate(Double.parseDouble(display.getText()));
        op = s;
        start = true;
      }
    }
  }

  public void calculate(double n) {
    if (op.equals("+"))
      arg += n;
    else if (op.equals("-"))
      arg -= n;
    else if (op.equals("*"))
      arg *= n;
    else if (op.equals("/"))
      arg /= n;
    else if (op.equals("="))
      arg = n;
    display.setText("" + arg);
  }

  private JTextField display;

  private double arg = 0;

  private String op = "=";

  private boolean start = true;
}

class CalculatorFrame extends JFrame {
  public CalculatorFrame() {
    setTitle("Calculator");
    setSize(200, 200);

    Container contentPane = getContentPane();
    contentPane.add(new CalculatorPanel());
  }
}

The post Java Program for calculator first appeared on Student Projects.

We bring to you the ultimate solution for all your struggles, The SUDOKU Solver.

As you know, now a days mathematical puzzle-SUDOKU is in boom all over the world. Sudoku is a 9X9 matrix with nine 3×3 sub-matrices, that we need to fill by entering the numbers from 1 through 9, without the repetition of the a number in the rows, columns or in the sub matrices.

We can get the Sudoku puzzle in ease by different means, as discussed. You might have struggled a lot to solve the same. To be true, even me too. Here I developed a fast and robust package, that solves the puzzles, that are not easy to solve by hands. It will solve the Sudoku entered in fraction of a milli-second and will display the solved result.

Click here to download the executable files

When the code executes, a blank Sudoku will be displayed with 9×9 red boxes. The user is needed to enter the numbers corresponding to the source puzzle (Figure 1). To enter this, user should use the arrow keys to cruse to the required box. The selected box will be highlighted with a blue boundary. You have to enter the number through the keyboard. Once you have done entering all the numbers in the puzzle just hit the ‘Enter’ key on the keyboard till you get the solved result (Figure 2). If the Sudoku cannot be solved by this program a message will be displayed telling that the given puzzle cannot be solved.

The post Sudoku Solver using C++ first appeared on Student Projects.