使用Java创建正确的表达式

huangapple
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英文:

Create correct expression with java

问题

我遇到了一个问题，需要你的帮助。我有以下情景：

我有三个值：

  • 布尔值 visible
  • 整数 views
  • 整数 executions

现在，我想要创建一个表达式，将数据库中的 hidden 设置为 true 或 false。

我希望实现以下情况：

  1. 如果 visible 为 true，并且 views <= 4 或 executions <= 5，则 hidden = false。

我的代码如下：

  1. calculateHiddenFlag(boolean visible, int views, int executions) {
  2.     return visible && (views <= 4 || executions <= 5);
  3. }

有人可以帮助我吗？

单元测试：

  1. @Test
  2. public void calculateHiddenFlag_false_if_hidden_false() {
  3.     assertFalse(ImportHelper.calculateHiddenFlag(false, 0, 0));
  4. }
  6. @Test
  7. public void calculateHiddenFlag_true_if_hidden_true_and_views_leq4() {
  8.     assertTrue(ImportHelper.calculateHiddenFlag(true, 4, 0));
  9. }
  11. @Test
  12. public void calculateHiddenFlag_true_if_hidden_true_and_executions_leq5() {
  13.     assertTrue(ImportHelper.calculateHiddenFlag(true, 0, 5));
  14. }
  16. @Test
  17. public void calculateHiddenFlag_false_if_hidden_true_but_views_gt4() {
  18.     assertFalse(ImportHelper.calculateHiddenFlag(true, 10, 0));
  19. }
  21. @Test
  22. public void calculateHiddenFlag_false_if_hidden_true_but_executions_gt5() {
  23.     assertFalse(ImportHelper.calculateHiddenFlag(true, 0, 10));
  24. }
英文:

I'm sitting on a problem and need your help. I have the following scenario:

I have three values:

  1. boolean visible
  2. int views
  3. int executions

Now, I d'like to create a expression which sets hidden in my DB to true or false.

I should get this:

  1. If visible is true, views <=4 or executions <=5 then hidden = false

My code looks like this:

  1. calculateHiddenFlag(boolean visible, int views, int executions) {
  2.     return visible &amp;&amp; (views &lt;=4 || executions &lt;=5);
  3. }

Can someone support me?

Unit tests:

  1.     @Test
  2. public void calculateHiddenFlag_false_if_hidden_false() {
  3.     assertFalse(ImportHelper.calculateHiddenFlag(false, 0, 0));
  4. }
  6. @Test
  7. public void calculateHiddenFlag_true_if_hidden_true_and_views_leq4() {
  8.     assertTrue(ImportHelper.calculateHiddenFlag(true, 4, 0));
  9. }
  11. @Test
  12. public void calculateHiddenFlag_true_if_hidden_true_and_executions_leq5() {
  13.     assertTrue(ImportHelper.calculateHiddenFlag(true, 0, 5));
  14. }
  16. @Test
  17. public void calculateHiddenFlag_false_if_hidden_true_but_views_gt4() {
  18.     assertFalse(ImportHelper.calculateHiddenFlag(true, 10, 0));
  19. }
  21. @Test
  22. public void calculateHiddenFlag_false_if_hidden_true_but_executions_gt5() {
  23.     assertFalse(ImportHelper.calculateHiddenFlag(true, 0, 10));
  24. }

答案1

得分: 2

（根据下面的评论进行了编辑）

初始语句应解释为

“如果visible为true且views≤4，或者executions≤5，则hidden为false。”

在添加括号以遵循逻辑运算符的优先级后，应该是：

“如果visible为true且（views≤4或者executions≤5），则hidden为false。”

所以代码在字面上读起来就是你说的：

  1. calculateHiddenFlag(boolean visible, int views, int executions) {
  2.     return !(visible && (views <= 4 || executions <= 5));
  3. }

或者，可以使用两次德摩根定律，并根据逻辑运算符的优先级移除括号，改写为：

  1. calculateHiddenFlag(boolean visible, int views, int executions) {
  2.     return !visible || (views > 4 && executions > 5);
  3. }
英文:

(Edited according to comment below)

The initial statement should interpreted as

if visible is true AND views &lt;= 4 OR executions &lt;= 5 then hidden = false

and after adding parentheses to adhere to the Precedence of Logical Operators

if visible is true AND (views &lt;= 4 OR executions &lt;= 5) then hidden = false

So the code would be literally what you say when reading it:

  1. calculateHiddenFlag(boolean visible, int views, int executions) {
  2.     return !(visible &amp;&amp; (views&lt;=4 || executions&lt;=5));
  3. }

Or alternatively using some of De Morgan's laws two times and removing parentheses according to Precedence of Logical Operators

  1. calculateHiddenFlag(boolean visible, int views, int executions) {
  2.     return !visible || views&gt;4 &amp;&amp; executions&gt;5;
  3. }

huangapple
  • 本文由 发表于 2020年9月15日 22:21:15
  • 转载请务必保留本文链接：https://go.coder-hub.com/63903924.html
  • expression
  • java
  • operators
  • regex
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