In the code below I want to use the "term" attribute to generate the hash code. How to use this String attribute to generate hash code?
class Term {
String term;
@Override
public boolean equals(Object o) {
if (o instanceof Term) {
return this.term.equals(((Term)o).term);
}
return false;
}
@Override
public int hashCode() {
}
}
Just use String#hashCode() method with a null check. That would be enough:
@Override
public int hashCode() {
int prime = 31;
return prime + (term == null ? 0 : term.hashCode());
}
You should also modify the equals() method to do the null check on this.term before hand.
this.term is null.You can use Objects if you use JDK 1.7 or more.
@Override
public int hashCode() {
int prime = 31;
return prime + Objects.hashCode(this.stringAtrribute);
}
For multiple attributes:
@Override
public int hashCode() {
int prime = 31;
return prime + Objects.hash(this.attributOne,this.atrributeTwo);
}
And yes ofcourse as with the previous answers the equal and hashcode method should have consistency.
Eclipse can write this code for you. Just choose Generate hashCode and equals from the Source menu.
