是这样的，HashMap的key值有重复，但还是被打印了，equals方法和hashCod已重写了，这是为什么呢？
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public class Student {
    private String name;
    private Integer score;
    public Student(String name, Integer score) {
        this.name = name;
        this.score = score;
    }
    public String toString() {
        return "Student [name=" + name + ", score=" + score + "]";
    }
    public Integer hasCode() {
        return name.hashCode() + score.hashCode() * 31;
    }
    public boolean equals(Object obj) {
        Student p = (Student) obj;
        if (this.name == p.name && this.score == p.score) {
            return true;
        }
        return false;
    }
}
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import java.util.Set;
import java.util.HashMap;
public class TestHashMap {
    public static void main(String[] args) {
        HashMap<Student, Student> ha = new HashMap<Student, Student>();
        ha.put(new Student("小理", 25), new Student("小理", 25));
        ha.put(new Student("小刚", 21), new Student("小娟", 23));
        ha.put(new Student("小理", 25), new Student("小理", 25));
        ha.put(new Student("大刚", 22), new Student("小青", 24));
        ha.put(new Student("小名", 21), new Student("小晓", 21));
             Set<Student> s=ha.keySet();
         for(Student sl : s)
         {
         System.out.println(sl);
         }
        
    }
}

@Override//最好把这个加上，可以帮你检查继承
public int hashCode() {//方法名写错了
    return name.hashCode() + score.hashCode() * 31;
}

//话说论坛这两天老进不去，不知道怎么回事

感谢