public native int hashCode(); 

public V put(K key, V value) {

    if (key == null)

      return putForNullKey(value);

    int hash = hash(key.hashCode());

    int i = indexFor(hash, table.length);

    for (Entry<K,V> e = table[i]; e != null; e = e.next) {

      Object k;

      if (e.hash == hash && ((k = e.key) == key || key.equals(k))) {

        V oldValue = e.value;

        e.value = value;

        e.recordAccess(this);

        return oldValue;

      }

    }

    modCount++;

    addEntry(hash, key, value, i);

    return null;

  } 

static inline intptr_t get_next_hash(Thread * Self, oop obj) {

 intptr_t value = 0 ;

 if (hashCode == 0) {

   // This form uses an unguarded global Park-Miller RNG,

   // so it's possible for two threads to race and generate the same RNG.

   // On MP system we'll have lots of RW access to a global, so the

   // mechanism induces lots of coherency traffic.

   value = os::random() ;

 } else

 if (hashCode == 1) {

   // This variation has the property of being stable (idempotent)

   // between STW operations. This can be useful in some of the 1-0

   // synchronization schemes.

   intptr_t addrBits = intptr_t(obj) >> 3 ;

   value = addrBits ^ (addrBits >> 5) ^ GVars.stwRandom ;

 } else

 if (hashCode == 2) {

   value = 1 ;      // for sensitivity testing

 } else

 if (hashCode == 3) {

   value = ++GVars.hcSequence ;

 } else

 if (hashCode == 4) {

   value = intptr_t(obj) ;

 } else {

   // Marsaglia's xor-shift scheme with thread-specific state

   // This is probably the best overall implementation -- we'll

   // likely make this the default in future releases.

   unsigned t = Self->_hashStateX ;

   t ^= (t << 11) ;

   Self->_hashStateX = Self->_hashStateY ;

   Self->_hashStateY = Self->_hashStateZ ;

   Self->_hashStateZ = Self->_hashStateW ;

   unsigned v = Self->_hashStateW ;

   v = (v ^ (v >> 19)) ^ (t ^ (t >> 8)) ;

   Self->_hashStateW = v ;

   value = v ;

 }

 

 value &= markOopDesc::hash_mask;

 if (value == 0) value = 0xBAD ;

 assert (value != markOopDesc::no_hash, "invariant") ;

 TEVENT (hashCode: GENERATE) ;

 return value;

} 

package com.cxh.test1;

import java.util.HashMap;

import java.util.HashSet;

import java.util.Set;

class People{

  private String name;

  private int age;  

  public People(String name,int age) {

    this.name = name;

    this.age = age;

  }   

  public void setAge(int age){

    this.age = age;

  }    

  @Override

  public boolean equals(Object obj) {

    // TODO Auto-generated method stub

    return this.name.equals(((People)obj).name) && this.age== ((People)obj).age;

  }

}

public class Main {

  public static void main(String[] args) {  

    People p1 = new People("Jack", 12);

    System.out.println(p1.hashCode());    

    HashMap<People, Integer> hashMap = new HashMap<People, Integer>();

    hashMap.put(p1, 1);

    System.out.println(hashMap.get(new People("Jack", 12)));

  }

} 

 public V get(Object key) {

    if (key == null)

      return getForNullKey();

    int hash = hash(key.hashCode());

    for (Entry<K,V> e = table[indexFor(hash, table.length)];

       e != null;

       e = e.next) {

      Object k;

      if (e.hash == hash && ((k = e.key) == key || key.equals(k)))

        return e.value;

    }

    return null;

  } 

package com.cxh.test1;

import java.util.HashMap;

import java.util.HashSet;

import java.util.Set; 

class People{

  private String name;

  private int age;

  public People(String name,int age) {

    this.name = name;

    this.age = age;

  }  

 public void setAge(int age){

    this.age = age;

  }  

  @Override

  public int hashCode() {

    // TODO Auto-generated method stub

    return name.hashCode()*37+age;

  } 

  @Override

  public boolean equals(Object obj) {

    // TODO Auto-generated method stub

    return this.name.equals(((People)obj).name) && this.age== ((People)obj).age;

  }

}

public class Main {

  public static void main(String[] args) {   

    People p1 = new People("Jack", 12);

    System.out.println(p1.hashCode());   

    HashMap<People, Integer> hashMap = new HashMap<People, Integer>();

    hashMap.put(p1, 1);  

    System.out.println(hashMap.get(new People("Jack", 12)));

  }

} 

package com.cxh.test1; 

import java.util.HashMap;

import java.util.HashSet;

import java.util.Set;

class People{

  private String name;

  private int age; 

  public People(String name,int age) {

    this.name = name;

    this.age = age;

  }  

  public void setAge(int age){

    this.age = age;

  } 

  @Override

  public int hashCode() {

    // TODO Auto-generated method stub

    return name.hashCode()*37+age;

  }  

  @Override

  public boolean equals(Object obj) {

    // TODO Auto-generated method stub

    return this.name.equals(((People)obj).name) && this.age== ((People)obj).age;

  }

}

public class Main {

  public static void main(String[] args) {  

    People p1 = new People("Jack", 12);

    System.out.println(p1.hashCode()); 

    HashMap<People, Integer> hashMap = new HashMap<People, Integer>();

    hashMap.put(p1, 1);

    p1.setAge(13);  

    System.out.println(hashMap.get(p1));

  }

}