44 lines
947 B
Plaintext
44 lines
947 B
Plaintext
Because ``++Object++`` implements ``++hashCode++``, any Java class can be put into a hash structure. However, classes that define ``++equals(Object)++`` but not ``++hashCode()++`` aren't truly hash-able because instances that are equivalent according to the ``++equals++`` method can return different hashes.
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== Noncompliant Code Example
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----
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public class Student { // no hashCode() method; not hash-able
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// ...
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public boolean equals(Object o) {
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// ...
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}
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}
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public class School {
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private Map<Student, Integer> studentBody = // okay so far
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new HashTable<Student, Integer>(); // Noncompliant
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// ...
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----
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== Compliant Solution
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----
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public class Student { // has hashCode() method; hash-able
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// ...
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public boolean equals(Object o) {
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// ...
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}
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public int hashCode() {
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// ...
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}
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}
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public class School {
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private Map<Student, Integer> studentBody = new HashTable<Student, Integer>();
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// ...
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----
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