軟體:eclipse
才開始用java設計東西，我覺得這個程式適用於初步想設計計算器的同學用，雖然很簡單，但我會慢慢更新自己所寫計算器，實現更強的邏輯。

例如：61-7*4=216（從左至右的簡單邏輯，還不完善）

程式碼：（有詳細註釋）

//大佬不適合看！
package layout;

import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
 

import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.border.Border;

public class CalculatorFrame extends JFrame {
	// 屬性
	JTextField Text = null;
	boolean beginNum = false;
	String num1 =
 
 null;
	String num2 = null;
	String operator = null;

	// 方法
	public CalculatorFrame() {
		setTitle("Borderlayout Demo");
		setSize(250, 300);
		setDefaultCloseOperation(EXIT_ON_CLOSE);

		// 獲取主內容面板
		Container contentPane = this.getContentPane();
		// 設定佈局方式：邊框型佈局
		contentPane.setLayout(new BorderLayout()
 
);

		// 單獨處理NORTH佈局
		// 獲得中間容器面板並放在主面板的NORTH
		JPanel pnlNorth = new JPanel();
		// 邊框型佈局
		pnlNorth.setLayout(new BorderLayout());
		// 放置
		contentPane.add(BorderLayout.NORTH, pnlNorth);
		// 文字框
		Text = new JTextField();
		// 按鈕（清零）
		JButton btnOK = new JButton("C");

		// 放置
		pnlNorth.add(BorderLayout.CENTER, Text);
		pnlNorth.add(BorderLayout.EAST, btnOK);

		// 單獨處理CENTER佈局
		// //獲得中間容器面板並放在主面板的CENTER
		String[] s = { "7", "8", "9", "+", "4", "5", "6", "-", "1", "2", "3","*", "0", "." ,"/", "="  };
		JPanel pnlNorthTow = new JPanel();
		// 放置
		contentPane.add(BorderLayout.CENTER, pnlNorthTow);

		// 網狀佈局
		pnlNorthTow.setLayout(new GridLayout(0, 4, 3, 3));
		// 內部類
		ActionListener listener = new ActionListener() {
			public void actionPerformed(ActionEvent event) {
				String cmd = event.getActionCommand();
				// JOptionPane.showMessageDialog(null, cmd);
				/*if (cmd.equals("0") || cmd.equals("1") || cmd.equals("2") || cmd.equals("3") || cmd.equals("4")
						|| cmd.equals("5") || cmd.equals("6") || cmd.equals("7") || cmd.equals("8")
						|| cmd.equals("9")) {*/
				if("0123456789".contains(cmd)){
					// 輸入1時（61顯示）
					if (beginNum) {
						Text.setText(Text.getText() + cmd);
					}
					// 輸入6時
					else {
						Text.setText(cmd);
						beginNum = true;
					}
				}
				
				// 輸入“—”時
				//if (cmd.equals("+") || cmd.equals("-") || cmd.equals("*") || cmd.equals("/")) {
				if("+-*/".contains(cmd)){
					beginNum = false;
					// 當operator為空的時候，與equals的區別
					if (operator == null) {
						// 文字框內容賦給num1
						num1 = Text.getText();
						// 減號賦給operator
						operator = cmd;
						// 清空文字框
						Text.setText(null);
					}
					// operator不為空時（輸入*的時候）
					else {
						// 把7賦給num2
						num2 = Text.getText();
						// 計算num1值並放在文字框裡面
						if(operator.equals("-"))
							num1 = String.valueOf(Integer.parseInt(num1) - Integer.parseInt(num2));
						if(operator.equals("+"))
							num1 = String.valueOf(Integer.parseInt(num1) + Integer.parseInt(num2));
						if(operator.equals("*"))
							num1 = String.valueOf(Integer.parseInt(num1) * Integer.parseInt(num2));
						if(operator.equals("/"))
							num1 = String.valueOf(((double)Integer.parseInt(num1) / Integer.parseInt(num2)));
						Text.setText(num1);
						// 把*賦給operator
						operator = cmd;
					}
				}
				//當輸等號時
					if ("=".equals(cmd)) {
						// 結束置為false
						beginNum = false;
						// 將4賦給num2
						num2 = Text.getText();
						if(operator.equals("-"))
							num1 = String.valueOf(Integer.parseInt(num1) - Integer.parseInt(num2));
						if(operator.equals("+"))
							num1 = String.valueOf(Integer.parseInt(num1) + Integer.parseInt(num2));
						if(operator.equals("*"))
							num1 = String.valueOf(Integer.parseInt(num1) * Integer.parseInt(num2));
						if(operator.equals("/"))
							num1 = String.valueOf(((double)Integer.parseInt(num1) / Integer.parseInt(num2)));
						Text.setText(String.valueOf(num1));
						num1 = null;
						//num2=null;
						operator = null;
					}
					if("C".equals(cmd)){
						Text.setText(null);
					}
			}		
		};
		for (int i = 0; i < 16; i++) {
			JButton btn = new JButton(s[i]);
			pnlNorthTow.add(btn); // 注意各個面板的add
			// 數字符號等輸入放置
			btn.addActionListener(listener);
		}
		// 按鈕輸入放置
		btnOK.addActionListener(listener);
	}

	public static void main(String[] args) {
		JFrame frame = new CalculatorFrame();
		frame.setVisible(true);
	}

}