如何在不同长度的输入上使用构建器？

huangapple
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英文:

How to use a Builder for different length of input?

问题

  1. 使用 Builder 模式来构建并返回对象。根据可用参数的数量，有一种定义好的顺序来调用方法。目前我在使用 if-else 块。在 Java 8 或更高版本中，是否有动态使用 builder 的替代方法？
  3. public Task createTask(String[] params){
  4.     if(params.length < 1){
  5.         throw new IllegalArgumentException();
  6.     }
  7.     else if(params.length == 1){
  8.         return new TaskBuilder().setOne(params[0]).build();
  9.     }
  10.     else if(params.length == 2){
  11.         return new TaskBuilder().setOne(params[0])
  12.                                 .setTwo(params[1]).build();
  13.     }
  14.     else if(params.length == 3){
  15.         return new TaskBuilder().setOne(params[0])
  16.                                 .setTwo(params[1])
  17.                                 .setThree(params[2]).build();
  18.     }
  19.     else if(params.length == 4){
  20.         return new TaskBuilder().setOne(params[0])
  21.                                 .setTwo(params[1])
  22.                                 .setThree(params[2])
  23.                                 .setFour(params[3]).build();
  25.     }
  26.     else if(params.length == 5){
  27.         return new TaskBuilder().setOne(params[0])
  28.                                 .setTwo(params[1])
  29.                                 .setThree(params[2])
  30.                                 .setFour(params[3])
  31.                                 .setFive(params[4]).build();
  33.     }
  34.     else{
  35.         throw new IllegalArgumentException();
  36.     }
  38. }
英文:

I am using a Builder(pattern) to build and return an object. There is a defined order depending on the number of available arguments on how the methods should be called. Currently I use if-else blocks. Is there a java 8 or higher alternative to use the builder dynamically?

  1. public Task createTask(String[] params){
  2. if(params.length &lt; 1){
  3. throw new IllegalArgumentException();
  4. }
  5. else if(params.length == 1){
  6. return new TaskBuilder().setOne(params[0]).build();
  7. }
  8. else if(params.length == 2){
  9. return new TaskBuilder().setOne(params[0])
  10. .setTwo(params[1]).build();
  11. }
  12. else if(params.length == 3){
  13. return new TaskBuilder().setOne(params[0])
  14. .setTwo(params[1])
  15. .setThree(params[2]).build();
  16. }
  17. else if(params.length == 4){
  18. return new TaskBuilder().setOne(params[0])
  19. .setTwo(params[1])
  20. .setThree(params[2])
  21. .setFour(params[3]).build();
  22. }
  23. else if(params.length == 5){
  24. return new TaskBuilder().setOne(params[0])
  25. .setTwo(params[1])
  26. .setThree(params[2])
  27. .setFour(params[3])
  28. .setFive(params[4]).build();
  29. }
  30. else{
  31. throw new IllegalArgumentException();
  32. }
  33. }

答案1

得分: 3

你不需要像函数引用那样的花哨东西。你所需要做的就是将构建器调用分解：

  1. public Task createTask(String[] params){
  2.     if (params.length < 1 || params.length > 5) {
  3.         throw new IllegalArgumentException();
  4.     }
  6.     TaskBuilder builder = new TaskBuilder();
  8.     if (params.length >= 1) { builder = builder.setOne(params[0]); }
  9.     if (params.length >= 2) { builder = builder.setTwo(params[1]); }
  10.     if (params.length >= 3) { builder = builder.setThree(params[2]); }
  11.     if (params.length >= 4) { builder = builder.setFour(params[3]); }
  12.     if (params.length >= 5) { builder = builder.setFive(params[4]); }
  13.     
  14.     return builder.build();
  15. }
英文:

You don't really need anything fancy like function references. All you have to do is break the builder calls up:

  1. public Task createTask(String[] params){
  2. if (params.length &lt; 1 || params.length &gt; 5) {
  3. throw new IllegalArgumentException();
  4. }
  5. TaskBuilder builder = new TaskBuilder();
  6. if (params.length &gt;= 1) { builder = builder.setOne(params[0]); }
  7. if (params.length &gt;= 2) { builder = builder.setTwo(params[1]); }
  8. if (params.length &gt;= 3) { builder = builder.setThree(params[2]); }
  9. if (params.length &gt;= 4) { builder = builder.setFour(params[3]); }
  10. if (params.length &gt;= 5) { builder = builder.setFive(params[4]); }
  11. return builder.build();
  12. }

huangapple
  • 本文由 发表于 2020年8月22日 02:50:47
  • 转载请务必保留本文链接：https://go.coder-hub.com/63528546.html
  • builder-pattern
  • java
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