用java编写一个简易计算器，要求拥有图形界面，可以显示运行过程即结果，可以进行简单的加减乘除以及符合运算

以下是一个简易计算器的Java代码，使用Swing库作为图形界面：

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class Calculator {
    private JFrame frame;
    private JTextField displayField;
    private String currentInput = "";
    private double result = 0;
    private String operator = "";

    public Calculator() {
        frame = new JFrame("Calculator");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(300, 300);

        JPanel panel = new JPanel(new GridLayout(4, 4));
        JButton button1 = new JButton("1");
        button1.addActionListener(new NumberListener());
        panel.add(button1);

        JButton button2 = new JButton("2");
        button2.addActionListener(new NumberListener());
        panel.add(button2);

        JButton button3 = new JButton("3");
        button3.addActionListener(new NumberListener());
        panel.add(button3);

        JButton buttonPlus = new JButton("+");
        buttonPlus.addActionListener(new OperatorListener());
        panel.add(buttonPlus);

        JButton button4 = new JButton("4");
        button4.addActionListener(new NumberListener());
        panel.add(button4);

        JButton button5 = new JButton("5");
        button5.addActionListener(new NumberListener());
        panel.add(button5);

        JButton button6 = new JButton("6");
        button6.addActionListener(new NumberListener());
        panel.add(button6);

        JButton buttonMinus = new JButton("-");
        buttonMinus.addActionListener(new OperatorListener());
        panel.add(buttonMinus);

        JButton button7 = new JButton("7");
        button7.addActionListener(new NumberListener());
        panel.add(button7);

        JButton button8 = new JButton("8");
        button8.addActionListener(new NumberListener());
        panel.add(button8);

        JButton button9 = new JButton("9");
        button9.addActionListener(new NumberListener());
        panel.add(button9);

        JButton buttonMultiply = new JButton("*");
        buttonMultiply.addActionListener(new OperatorListener());
        panel.add(buttonMultiply);

        JButton buttonClear = new JButton("C");
        buttonClear.addActionListener(new ClearListener());
        panel.add(buttonClear);

        JButton button0 = new JButton("0");
        button0.addActionListener(new NumberListener());
        panel.add(button0);

        JButton buttonEquals = new JButton("=");
        buttonEquals.addActionListener(new EqualsListener());
        panel.add(buttonEquals);

        JButton buttonDivide = new JButton("/");
        buttonDivide.addActionListener(new OperatorListener());
        panel.add(buttonDivide);

        displayField = new JTextField();
        displayField.setEditable(false);

        frame.getContentPane().add(BorderLayout.NORTH, displayField);
        frame.getContentPane().add(BorderLayout.CENTER, panel);

        frame.setVisible(true);
    }

    class NumberListener implements ActionListener {
        public void actionPerformed(ActionEvent event) {
            String digit = event.getActionCommand();
            currentInput += digit;
            displayField.setText(currentInput);
        }
    }

    class OperatorListener implements ActionListener {
        public void actionPerformed(ActionEvent event) {
            String op = event.getActionCommand();
            double input = Double.parseDouble(currentInput);
            currentInput = "";
            if (operator.equals("+")) {
                result += input;
            } else if (operator.equals("-")) {
                result -= input;
            } else if (operator.equals("*")) {
                result *= input;
            } else if (operator.equals("/")) {
                result /= input;
            } else {
                result = input;
            }
            operator = op;
            displayField.setText(Double.toString(result));
        }
    }

    class EqualsListener implements ActionListener {
        public void actionPerformed(ActionEvent event) {
            double input = Double.parseDouble(currentInput);
            currentInput = "";
            if (operator.equals("+")) {
                result += input;
            } else if (operator.equals("-")) {
                result -= input;
            } else if (operator.equals("*")) {
                result *= input;
            } else if (operator.equals("/")) {
                result /= input;
            } else {
                result = input;
            }
            operator = "";
            displayField.setText(Double.toString(result));
        }
    }

    class ClearListener implements ActionListener {
        public void actionPerformed(ActionEvent event) {
            currentInput = "";
            result = 0;
            operator = "";
            displayField.setText("");
        }
    }

    public static void main(String[] args) {
        Calculator calculator = new Calculator();
    }
}

该计算器可以进行简单的加减乘除运算，并且拥有图形界面，可以显示运算结果。用户可以通过点击数字按钮来输入数字，点击加减乘除按钮来选择运算符，点击等于按钮来计算结果。同时，用户也可以通过点击清空按钮来清空输入内容和计算结果。