Java 如何缩短此代码并减少重复性？
我做了一个简单的计算器，但是if语句非常重复和冗长。我想知道还有什么其他的解决方案可以缩短它，减少重复性。例如，使用一种方法（我已经尝试过但没有成功）或任何其他可用的技术。最好不要太高，因为我是初学者Java 如何缩短此代码并减少重复性？,java,Java,我做了一个简单的计算器，但是if语句非常重复和冗长。我想知道还有什么其他的解决方案可以缩短它，减少重复性。例如，使用一种方法（我已经尝试过但没有成功）或任何其他可用的技术。最好不要太高，因为我是初学者 import static java.lang.System.*; import static javax.swing.JOptionPane.*; import static java.lang.Integer.*; public class SimpleCalc { public
import static java.lang.System.*;
import static javax.swing.JOptionPane.*;
import static java.lang.Integer.*;
public class SimpleCalc {
public static void main(String[] args) {
String operator = showInputDialog("Choose operation: " + "\n" +
"[1] = Plus" + "\n" +
"[2] = Minus" + "\n" +
"[3] = Multiply" + "\n" +
"[4] = Divide" + "\n");
int c = parseInt(operator);
if (c > 4) {
showMessageDialog(null, "You cant do that.");
} else if (c == 1) {
String textA = showInputDialog("Enter first number: ");
String textB = showInputDialog("Enter second number: ");
int a = parseInt(textA);
int b = parseInt(textB);
showMessageDialog(null, a + " + " + b + " = " + (a + b));
} else if (c == 2) {
String textA = showInputDialog("Enter first number: ");
String textB = showInputDialog("Enter second number: ");
int a = parseInt(textA);
int b = parseInt(textB);
showMessageDialog(null, a + " - " + b + " = " + (a - b));
} else if (c == 3) {
String textA = showInputDialog("Enter first number: ");
String textB = showInputDialog("Enter second number: ");
int a = parseInt(textA);
int b = parseInt(textB);
showMessageDialog(null, a + " * " + b + " = " + (a * b));
} else if (c == 4) {
String textA = showInputDialog("Enter first number: ");
String textB = showInputDialog("Enter second number: ");
int a = parseInt(textA);
int b = parseInt(textB);
showMessageDialog(null, a + " / " + b + " = " + (a / b));
}
}
}
好,开始,；你可以移动
String textA = showInputDialog("Enter first number: ");
String textB = showInputDialog("Enter second number: ");
int a = parseInt(textA);
int b = parseInt(textB);
或者，您也可以使用方法或函数作为练习；但这并不会进一步缩短您的代码，真的。我还建议你研究一下Codegolf，你可以学到很多关于代码缩短的知识；你可以移动
String textA = showInputDialog("Enter first number: ");
String textB = showInputDialog("Enter second number: ");
int a = parseInt(textA);
int b = parseInt(textB);
String textA = showInputDialog("Enter first number: ");
String textB = showInputDialog("Enter second number: ");
int a = parseInt(textA);
int b = parseInt(textB);
switch(c) {
case 1:
showMessageDialog(null, a + " + " + b + " = " + (a+b));
break;
case 2:
...
default:
showMessageDialog(null, "You cant do that.");
String textA = showInputDialog("Enter first number: ");
String textB = showInputDialog("Enter second number: ");
int a = parseInt(textA);
int b = parseInt(textB);
switch(c) {
case 1:
showMessageDialog(null, a + " + " + b + " = " + (a+b));
break;
case 2:
...
default:
showMessageDialog(null, "You cant do that.");
有两种方法：
- 将公共代码放入方法中
- 将公共代码移动到当前方法的不同部分，以便无条件执行
- 将非公共代码放入可用于参数化公共代码的函数/方法/类中
在这种情况下，第二种方法效果最好；e、 g
if(c==1) {
String textA = showInputDialog("Enter first number: ");
String textB = showInputDialog("Enter second number: ");
int a = parseInt(textA);
int b = parseInt(textB);
showMessageDialog(null, a + " + " + b + " = " + (a+b));
}
else if (c==2) {
String textA = showInputDialog("Enter first number: ");
String textB = showInputDialog("Enter second number: ");
int a = parseInt(textA);
int b = parseInt(textB);
showMessageDialog(null, a + " - " + b + " = " + (a-b));
}
...
String textA = showInputDialog("Enter first number: ");
String textB = showInputDialog("Enter second number: ");
int a = parseInt(textA);
int b = parseInt(textB);
int result;
char op;
if (c == 1) {
result = a + b;
op = '+';
} else if (c == 2) {
result = a - b;
op = '-';
}
...
showMessageDialog(null, a + " " + op + " " + b + " = " + result);
（我留下了一个问题供您注意和解决……作为学习练习。）有几种方法：
- 将公共代码放入方法中
- 将公共代码移动到当前方法的不同部分，以便无条件执行
- 将非公共代码放入可用于参数化公共代码的函数/方法/类中
在这种情况下，第二种方法效果最好；e、 g
if(c==1) {
String textA = showInputDialog("Enter first number: ");
String textB = showInputDialog("Enter second number: ");
int a = parseInt(textA);
int b = parseInt(textB);
showMessageDialog(null, a + " + " + b + " = " + (a+b));
}
else if (c==2) {
String textA = showInputDialog("Enter first number: ");
String textB = showInputDialog("Enter second number: ");
int a = parseInt(textA);
int b = parseInt(textB);
showMessageDialog(null, a + " - " + b + " = " + (a-b));
}
...
String textA = showInputDialog("Enter first number: ");
String textB = showInputDialog("Enter second number: ");
int a = parseInt(textA);
int b = parseInt(textB);
int result;
char op;
if (c == 1) {
result = a + b;
op = '+';
} else if (c == 2) {
result = a - b;
op = '-';
}
...
showMessageDialog(null, a + " " + op + " " + b + " = " + result);
（我给你留下了一个问题，让你注意并整理一下……作为一个学习练习。）以下内容将是相同的，但不会反复重复相同的行。您还可以使用switch语句代替4个if/else if语句
public class SimpleCalc {
public static void main(String[] args) {
String operator = showInputDialog("Choose operation: " + "\n" +
"[1] = Plus" + "\n" +
"[2] = Minus" + "\n" +
"[3] = Multiply" + "\n" +
"[4] = Divide" + "\n");
int c = parseInt(operator);
if (c>4) {
showMessageDialog(null, "You cant do that.");
return;
}
String textA = showInputDialog("Enter first number: ");
String textB = showInputDialog("Enter second number: ");
int a = parseInt(textA);
int b = parseInt(textB);
if(c==1) {
showMessageDialog(null, a + " + " + b + " = " + (a+b));
}
else if (c==2) {
showMessageDialog(null, a + " - " + b + " = " + (a-b));
}
else if (c==3) {
showMessageDialog(null, a + " * " + b + " = " + (a*b));
}
else if (c==4) {
showMessageDialog(null, a + " / " + b + " = " + (a/b));
}
}
}
以下内容将是相同的，但不会反复重复相同的行。您还可以使用switch语句代替4个if/else if语句
public class SimpleCalc {
public static void main(String[] args) {
String operator = showInputDialog("Choose operation: " + "\n" +
"[1] = Plus" + "\n" +
"[2] = Minus" + "\n" +
"[3] = Multiply" + "\n" +
"[4] = Divide" + "\n");
int c = parseInt(operator);
if (c>4) {
showMessageDialog(null, "You cant do that.");
return;
}
String textA = showInputDialog("Enter first number: ");
String textB = showInputDialog("Enter second number: ");
int a = parseInt(textA);
int b = parseInt(textB);
if(c==1) {
showMessageDialog(null, a + " + " + b + " = " + (a+b));
}
else if (c==2) {
showMessageDialog(null, a + " - " + b + " = " + (a-b));
}
else if (c==3) {
showMessageDialog(null, a + " * " + b + " = " + (a*b));
}
else if (c==4) {
showMessageDialog(null, a + " / " + b + " = " + (a/b));
}
}
}
只是为了好玩。找出常见的东西！并处理需要实现一元运算符的可能性。您可能还希望将其放入一个循环中，并添加一个exit命令
public class SimpleCalc {
public static void main(String[] args) {
String operator = showInputDialog(
"Choose operation: " + "\n" +
"[1] = Add" + "\n" +
"[2] = Subtract" + "\n" +
"[3] = Multiply" + "\n" +
"[4] = Divide" + "\n");
"[5] = Negate" + "\n");
int c = parseInt(operator);
int operand_count = 0;
switch (c) {
case 1:
case 2:
case 3:
case 4:
operand_count = 2;
break;
case 5:
operand_count = 1;
break;
default:
showMessageDialog(null, "You cant do that.");
return(-1);
}
int a = 0;
int b = 0;
if (operand_count >= 1) {
String textA = showInputDialog("Enter first number: ");
int a = parseInt(textA);
}
if (operand_count >= 2) {
String textB = showInputDialog("Enter second number: ");
int b = parseInt(textB);
}
char * opname = "";
int result = 0;
switch (c) {
case 1:
opname = "+";
result = a + b;
break;
case 2:
opname = "-";
result = a - b;
break;
case 3:
opname = "*";
result = a * b;
break;
case 4:
opname = "/";
result = a / b;
break;
case 5:
opname = "-";
result = -a;
break;
}
if (operand_count == 1) {
showMessageDialog(null, opname + " (" + a + ") = " result);
} else {
showMessageDialog(null, a + " " + opname + " " + b + " = " + result);
}
}
}
只是为了好玩。找出常见的东西！并处理需要实现一元运算符的可能性。您可能还希望将其放入一个循环中，并添加一个exit命令
public class SimpleCalc {
public static void main(String[] args) {
String operator = showInputDialog(
"Choose operation: " + "\n" +
"[1] = Add" + "\n" +
"[2] = Subtract" + "\n" +
"[3] = Multiply" + "\n" +
"[4] = Divide" + "\n");
"[5] = Negate" + "\n");
int c = parseInt(operator);
int operand_count = 0;
switch (c) {
case 1:
case 2:
case 3:
case 4:
operand_count = 2;
break;
case 5:
operand_count = 1;
break;
default:
showMessageDialog(null, "You cant do that.");
return(-1);
}
int a = 0;
int b = 0;
if (operand_count >= 1) {
String textA = showInputDialog("Enter first number: ");
int a = parseInt(textA);
}
if (operand_count >= 2) {
String textB = showInputDialog("Enter second number: ");
int b = parseInt(textB);
}
char * opname = "";
int result = 0;
switch (c) {
case 1:
opname = "+";
result = a + b;
break;
case 2:
opname = "-";
result = a - b;
break;
case 3:
opname = "*";
result = a * b;
break;
case 4:
opname = "/";
result = a / b;
break;
case 5:
opname = "-";
result = -a;
break;
}
if (operand_count == 1) {
showMessageDialog(null, opname + " (" + a + ") = " result);
} else {
showMessageDialog(null, a + " " + opname + " " + b + " = " + result);
}
}
}
这个问题更适合于开关用例，并遵循S.O.L.I.D。程序。这个问题更适合于开关用例，并遵循S.O.L.I.D。程序。