漢字的hashcode實現

 1.問題來源

       最近想看看JDK源碼，在看Object.hashCode()方法時，突然遺忘了java對漢字的hash處理，於是想總結下這個簡單的問題。

2.代碼分析

·      附上一個漢字轉ASSCII碼的代碼

public class ChineseToAss {

  public static void main(String[] arg) {
    String str = "王";
    char[] chinese = new char[str.length()];
    chinese = str.toCharArray();
    StringBuffer sb = new StringBuffer();
    for (int i = 0; i < chinese.length; i++) {
      System.out.print((int) chinese[i] + " ");
      sb.append((int) chinese[i] + ",");
    }
  }
}

 

      可以看出"王"的ASSCII碼值爲29579

3.本人學習時的誤解

public class Clone {

  public static void main(String[] agv){
    Student student1 = new Student("小王", 20);
    System.out.println("王".hashCode());
  }
}
class people{
  private Integer tall;

  public Integer getTall() {
    return tall;
  }

  public void setTall(Integer tall) {
    this.tall = tall;
  }
}
class Student extends people{
  private String name;
  private Integer age;

  public Student(String name, Integer age) {
    this.name = name;
    this.age = age;
  }

  public String getName() {
    return name;
  }

  public void setName(String name) {
    this.name = name;
  }

  public Integer getAge() {
    return age;
  }

  public void setAge(Integer age) {
    this.age = age;
  }

  @Override
  public boolean equals(Object o) {
    if (this == o) {
      return true;
    }
    if (!(o instanceof Student)) {
      return false;
    }
    Student student = (Student) o;
    return Objects.equals(getName(), student.getName()) &&
        Objects.equals(getAge(), student.getAge());
  }

  @Override
  public int hashCode() {
    return Objects.hash(getName(), getAge());
  }

  在第5行的斷點調試中起初沒有意識到漢字的ASCII碼，導致糾結浪費了快半小時；

4.總結

              1.Java漢字在計算hashcode時會轉化爲ASCII碼，然後和普通字符一樣，每次乘以31累加；