Question

如何制作if else语句功能

boolean condition1;
boolean condition2;

final Object a = new Object();
final Object b = new Object();
final Object c = new Object();
final Object d = new Object();

if (condition1 && condition2) {
   return a;
}
else if (condition1 && !condition2) {
   return b;
}
else if (!condition1 && condition2) {
   return c;
}
else {
   return d;
}

我想知道如何重构这种类型的条件语句以使其更具功能性，而不会优先考虑性能上的开销。

我在考虑将谓词映射到对象，这是一种方法吗？

Answer 1

我添加了两个条件来增加它的味道。 if / else语句可以非常深入，因此您可以使用逐位来澄清事物并合并条件。对我而言，这澄清了代码 - 无论有多少条件，都会导致代码深入一层。

final int BIT_CONDITION_1 = 0x01;
final int BIT_CONDITION_2 = 0x02;
final int BIT_CONDITION_3 = 0x04;
final int BIT_CONDITION_4 = 0x08;


boolean condition1 = false;
boolean condition2 = false;
boolean condition3 = false;
boolean condition4 = false;

int mergedConditions = 0;
if (condition1)
    mergedConditions |= BIT_CONDITION_1;
if (condition2)
    mergedConditions |= BIT_CONDITION_2;
if (condition3)
    mergedConditions |= BIT_CONDITION_3;
if (condition4)
    mergedConditions |= BIT_CONDITION_4;
// continue as needed

// now you can check all conditions using the set bits.
switch(mergedConditions) {
    case 0:      // no bits set
        System.out.println("No bits set");
        break;
    case 1:
        System.out.println("Conditions set = 1");
        break;
    case 2:
        System.out.println("Conditions set = 2");
        break;
    // You can also clarify case statements by using constants
    case (BIT_CONDITION_1 | BIT_CONDITION_2):
        System.out.println("Conditions set = 1,2");
        break;
    case 4:
        System.out.println("Conditions set = 3");
        break;
    case 5:
        System.out.println("Conditions set = 1,3");
        break;
    case 6:
        System.out.println("Conditions set = 2,3");
        break;
    case 7:
        System.out.println("Conditions set = 1,2,3");
        break;
    case 8:
        System.out.println("Conditions set = 4");
        break;
    case 9:
        System.out.println("Conditions set = 1,4");
        break;
    case 10:
        System.out.println("Conditions set = 2,4");
        break;
    case 11:
        System.out.println("Conditions set = 1,2,4");
        break;
    // etc ... Continue as needed
        }

Answer 2

对于两个条件，if / then / else语句没有任何问题。如果您有更多条件，可以使用真值表“简化”代码。

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不确定这是否是您的想法，但这是分派多个条件的典型方式。乍一看它看起来很神秘，如果你记录所有条件的整个真值表，它可能非常安全，因为它迫使你考虑所有可能的组合。当你有两个以上的条件时，这真的有用。

将多个if-else语句转换为更具功能性

2 个答案: