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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.*;
  5. import java.io.*;
  6.  
  7. /* Name of the class has to be "Main" only if the class is public. */
  8. class Ideone
  9. {
  10. 	public static void main (String[] args) throws java.lang.Exception
  11. 	{
  12. 		new Ideone().executar();
  13. 	}
  14.  
  15. 	public void executar(){
  16. 		Map<String, ClasseProHashMap> mapa = new HashMap<String, ClasseProHashMap>();
  17.  
  18. 		ClasseProHashMap cp1 = new ClasseProHashMap("Primeiro", "Joao", 100);
  19. 		ClasseProHashMap cp2 = new ClasseProHashMap("Segundo", "Jose", 200);
  20.  
  21. 		mapa.put("Primeiro", cp1);
  22. 		mapa.put("Segundo", cp2);
  23.  
  24. 		ClasseProHashMap testandoGet = mapa.get("Segundo");
  25.  
  26. 		testandoGet.imprimir();
  27.  
  28. 		ClasseProHashMap testandoGetErrado = mapa.get("ChaveErrada");
  29.  
  30. 		testandoGetErrado.imprimir(); // nullpointerexception
  31. 	}
  32.  
  33. 	class ClasseProHashMap{
  34. 		String chave;
  35. 		String nome;
  36. 		int valor;
  37.  
  38. 		public ClasseProHashMap(String c, String n, int v){
  39. 			this.chave = c;
  40. 			this.nome = n;
  41. 			this.valor = v;
  42. 		}
  43.  
  44. 		public void imprimir(){
  45. 			System.out.println("Chave: " + chave + "  Nome: " + nome + " Valor: " + valor);
  46. 		}
  47. 	}
  48. }
Runtime error #stdin #stdout #stderr 0.04s 711168KB
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stdin
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Standard input is empty
stdout
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Chave: Segundo  Nome: Jose Valor: 200
stderr
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Exception in thread "main" java.lang.NullPointerException
	at Ideone.executar(Main.java:30)
	at Ideone.main(Main.java:12)
https://ideone.com/ZWhgDm
language:
Java (HotSpot 12)
created:
9 years ago
visibility:
public

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