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  1. import java.util.*;
  2. import java.lang.*;
  3. import java.io.*;
  4.  
  5. class Ideone
  6. {
  7. 	public static void main (String[] args) throws java.lang.Exception
  8. 	{
  9. 		ResultOfIndexOf result = StringUtil.indexOf("hello, world", 'l');
  10. 		if (result.isFound())
  11. 			System.out.println(String.format("index=%d", result.foundIndex()));
  12. 	}
  13. }
  14.  
  15. class StringUtil {
  16. 	public static ResultOfIndexOf indexOf(String haystack, char needle) {
  17. 		for (int i = 0; i < haystack.length(); ++i)
  18. 			if (haystack.charAt(i) == needle)
  19. 				return new ResultOfIndexOf(i);
  20. 		return new ResultOfIndexOf();
  21. 	}
  22. }
  23.  
  24. class ResultOfIndexOf {
  25. 	private final boolean isFound;
  26. 	private final int foundIndex;
  27. 	ResultOfIndexOf() {
  28. 		this(false, 0);
  29. 	}
  30. 	ResultOfIndexOf(int foundIndex) {
  31. 		this(true, foundIndex);
  32. 	}
  33. 	private ResultOfIndexOf(boolean isFound, int foundIndex) {
  34. 		this.isFound = isFound;
  35. 		this.foundIndex = foundIndex;
  36. 	}
  37. 	public boolean isFound() {
  38. 		return isFound;
  39. 	}
  40. 	public int foundIndex() {
  41. 		if (!isFound)
  42. 			throw new RuntimeException("index not found");
  43. 		return foundIndex;
  44. 	}
  45. }
  46.  
Success #stdin #stdout 0.05s 2184192KB
comments (?)
stdin 
Standard input is empty
stdout 
index=2
https://ideone.com/mqp4fT
qiita - result_of_index_of sample impl 1
language:
Java (HotSpot 12)
created:
5 years ago
visibility:
public

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