Added java/collections and java/error handling sample code

1 files changed, 15 insertions, 0 deletions

diff --git a/java/10-collections/hashcode-contract.txt b/java/10-collections/hashcode-contract.txt
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+   Whenever it is invoked on the same object more than once during an execu-
+   tion of a Java application, the hashCode() method must consistently return
+   the same integer, provided no information used in equals() comparisons
+   on the object is modified. This integer need not remain consistent from one
+   execution of an application to another execution of the same application.
+   
+   If two objects are equal according to the equals(Object) method, then
+   calling the hashCode() method on each of the two objects must produce the
+   same integer result.
+   
+   It is NOT required that if two objects are unequal according to the
+   equals(java.lang.Object) method, then calling the hashCode() method
+   on each of the two objects must produce distinct integer results. However,
+   the programmer should be aware that producing distinct integer results for
+   unequal objects may improve the performance of hashtables.