计算器代码如下：
1 package ljm.calculator; 2 3 import javax.swing.*; 4 import java.awt.*; 5 import java.io.Serializable; 6 import java.math.*; 7 8 public class Main { 9 public static void main(String[] args) { 10 new Calculator("敏敏敏牌计算器 - ljm@lpqo.cn"); 11 } 12 } 13 14 class Calculator extends JFrame { 15 private TextArea show; // 显示 16 17 public Calculator(String t){ 18 super(t); 19 setLayout(null); 20 setSize(430,488); 21 setVisible(true); 22 setLocationRelativeTo(null); 23 setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 24 setResizable(false); 25 this.setBackground(new Color(237, 239, 238)); 26 27 setShow(); 28 addBut(); 29 setVisible(true); 30 } 31 32 private void setShow() { 33 show = new TextArea("",8,52,1); 34 show.setSize(415,102); 35 show.setLocation(0,0); 36 show.setFont(new Font("", Font.BOLD, 40)); 37 show.setBackground(Color.WHITE); 38 show.setForeground(new Color(48, 48, 48)); 39 show.setEditable(false); 40 show.setText(0 + ""); 41 this.add(show); 42 } 43 44 private double nub1 = 0; // 数1 45 private double nub2 = 0; // 数2 46 private String snub2 = ""; // 数2的字符串型 47 private int f = '+'; // 运算符号 48 private boolean isDoc = false; // 是否有小数点 49 private boolean isEqual = false; // 是否点击等于 50 private int nubLen = 0; 51 52 private void setBut(String s, int i, int j, int x, int y, final int c) { 53 Button b = new Button(s); 54 b.setLocation(x, y); 55 b.setSize(i, j); 56 b.setFont(new Font("", Font.BOLD, 35)); 57 b.setBackground(new Color(254, 254, 254)); 58 b.setForeground(new Color(88, 92, 100)); 59 60 // 计算逻辑算法 61 // Ljm ljm@lpqo.cn 62 // 2020.6.23 JXUT 63 b.addActionListener(e -> { 64 if (c < 10) { 65 // 数字0-9 66 if (isEqual) { 67 nub1 = 0; 68 } 69 if (nubLen > 20) { 70 return; 71 } 72 if (c == 0 && nub2 == 0 ) { 73 return; 74 } 75 snub2 += String.valueOf(c); 76 show.setText(snub2); 77 nubLen = show.getText().length(); 78 nub2 = Double.parseDouble(snub2); 79 80 } else if (c == '.') { 81 // 小数 82 if (nubLen > 20) { 83 return; 84 } 85 if (!isDoc) { 86 if (nub2 != 0) { 87 snub2 += "."; 88 } else { 89 snub2 = "0."; 90 } 91 nub2 = Double.parseDouble(snub2); 92 show.setText(snub2); 93 isDoc = true; 94 } 95 96 } else if (c == 'S') { 97 // 结果相反数 98 if (Double.parseDouble(show.getText()) == nub1) { 99 nub1 = 0 - nub1; 100 showf(nub1 +""); 101 } else { 102 nub2 = 0 -nub2; 103 showf(nub2 +""); 104 } 105 } else if (c == 'C') { 106 // 归零 107 nub1 = 0; 108 nub2 = 0; 109 snub2 = ""; 110 f = '+'; 111 isDoc = false; 112 isEqual = false; 113 nubLen = 0; 114 showf("0"); 115 } else { 116 isEqual = false; 117 nubLen = 0; 118 119 switch (f) { 120 case '/': 121 // 除法 122 nub1 = DoubleUtil.divide(nub1, nub2); 123 break; 124 case '*': 125 // 乘法 126 nub1 = DoubleUtil.mul(nub1, nub2); 127 break; 128 case '-': 129 // 减法 130 nub1 = DoubleUtil.sub(nub1, nub2); 131 break; 132 case '+': 133 // 加法 134 nub1 = DoubleUtil.add(nub1, nub2); 135 break; 136 } 137 138 showf(nub1 + ""); 139 if (c != '=') { 140 f = c; 141 } else { 142 // 等于 143 f = '+'; 144 isEqual = true; 145 } 146 147 nub2 = 0; 148 snub2 = ""; 149 isDoc = false; 150 } 151 }); 152 this.add(b); 153 } 154 155 156 // 去0小数 157 private void showf(String s ){ 158 double td = Double.parseDouble(s); 159 int ti = (int)td; 160 161 if (td == ti) { 162 show.setText(ti +""); 163 } else { 164 show.setText(td + ""); 165 } 166 } 167 168 private void addBut() { 169 setBut("AC", 215, 70, 0, 100, 'C'); 170 setBut("±", 107, 70, 214, 100, 'S'); 171 setBut("÷", 108, 70, 312, 100, '/'); 172 173 setBut("7", 107, 70, 0, 170, 7); 174 setBut("8", 108, 70, 107, 170, 8); 175 setBut("9", 107, 70, 214, 170, 9); 176 setBut("×", 108, 70, 312, 170, '*'); 177 178 setBut("4", 107, 70, 0, 240, 4); 179 setBut("5", 108, 70, 107, 240, 5); 180 setBut("6", 107, 70, 214, 240, 6); 181 setBut("-", 108, 70, 312, 240, '-'); 182 183 setBut("1", 107, 70, 0, 310, 1); 184 setBut("2", 108, 70, 107, 310, 2); 185 setBut("3", 107, 70, 214, 310, 3); 186 setBut("+", 108, 70, 312, 310, '+'); 187 188 setBut("0", 107, 70, 0, 380, 0); 189 setBut(".", 108, 70, 107, 380, '.'); 190 setBut("=", 215, 70, 214, 380, '='); 191 } 192 193 } 194 195 // BigDecimal的Double精确计算 196 class DoubleUtil implements Serializable { 197 private static final long serialVersionUID = -3345205828566485102L; 198 private static final Integer DEF_DIV_SCALE = 40; // 除法精度 199 200 // 精确加 201 public static Double add(Double value1, Double value2) { 202 BigDecimal b1 = new BigDecimal(Double.toString(value1)); 203 BigDecimal b2 = new BigDecimal(Double.toString(value2)); 204 return b1.add(b2).doubleValue(); 205 } 206 207 // 精确减 208 public static double sub(Double value1, Double value2) { 209 BigDecimal b1 = new BigDecimal(Double.toString(value1)); 210 BigDecimal b2 = new BigDecimal(Double.toString(value2)); 211 return b1.subtract(b2).doubleValue(); 212 } 213 214 // 精确乘 215 public static Double mul(Double value1, Double value2) { 216 BigDecimal b1 = new BigDecimal(Double.toString(value1)); 217 BigDecimal b2 = new BigDecimal(Double.toString(value2)); 218 return b1.multiply(b2).doubleValue(); 219 } 220 221 // 精确除 精度为 DEF_DIV_SCALE 222 public static Double divide(Double dividend, Double divisor) { 223 return divide(dividend, divisor, DEF_DIV_SCALE); 224 } 225 226 // 精确除 227 public static double divide(Double dividend, Double divisor, Integer scale) { 228 if (scale < 0) { 229 return -1; 230 } 231 BigDecimal b1 = new BigDecimal(Double.toString(dividend)); 232 BigDecimal b2 = new BigDecimal(Double.toString(divisor)); 233 return b1.divide(b2, scale, RoundingMode.HALF_UP).doubleValue(); 234 } 235 236 }
运行截图如下：
敬请指正。