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POOverriding equals() & hashCode() in sub classes ... considering super fields
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copied!<p>Is there a specific rule on how Overriding <code>equals()</code> & <code>hashCode()</code> in <strong>sub classes</strong> considering <strong>super fields</strong> ?? knowing that there is many parameters : super fields are private/public , with/without getter ...</p> <p>For instance, Netbeans generated equals() & hashCode() will not consider the super fields ... and</p> <pre><code> new HomoSapiens("M", "80", "1.80", "Cammeron", "VeryHot").equals( new HomoSapiens("F", "50", "1.50", "Cammeron", "VeryHot")) </code></pre> <p>will return true :(</p> <pre><code>public class Hominidae { public String gender; public String weight; public String height; public Hominidae(String gender, String weight, String height) { this.gender = gender; this.weight = weight; this.height = height; } ... } public class HomoSapiens extends Hominidae { public String name; public String faceBookNickname; public HomoSapiens(String gender, String weight, String height, String name, String facebookId) { super(gender, weight, height); this.name = name; this.faceBookNickname = facebookId; } ... } </code></pre> <p>If you want to see the Netbeans generated equals() & hashCode() :</p> <pre><code>public class Hominidae { ... @Override public boolean equals(Object obj) { if (obj == null) { return false; } if (getClass() != obj.getClass()) { return false; } final Hominidae other = (Hominidae) obj; if ((this.gender == null) ? (other.gender != null) : !this.gender.equals(other.gender)) { return false; } if ((this.weight == null) ? (other.weight != null) : !this.weight.equals(other.weight)) { return false; } if ((this.height == null) ? (other.height != null) : !this.height.equals(other.height)) { return false; } return true; } @Override public int hashCode() { int hash = 5; hash = 37 * hash + (this.gender != null ? this.gender.hashCode() : 0); hash = 37 * hash + (this.weight != null ? this.weight.hashCode() : 0); hash = 37 * hash + (this.height != null ? this.height.hashCode() : 0); return hash; } } public class HomoSapiens extends Hominidae { ... @Override public boolean equals(Object obj) { if (obj == null) { return false; } if (getClass() != obj.getClass()) { return false; } final HomoSapiens other = (HomoSapiens) obj; if ((this.name == null) ? (other.name != null) : !this.name.equals(other.name)) { return false; } if ((this.faceBookNickname == null) ? (other.faceBookNickname != null) : !this.faceBookNickname.equals(other.faceBookNickname)) { return false; } return true; } @Override public int hashCode() { int hash = 7; hash = 89 * hash + (this.name != null ? this.name.hashCode() : 0); hash = 89 * hash + (this.faceBookNickname != null ? this.faceBookNickname.hashCode() : 0); return hash; } } </code></pre>

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