Java tutorial
//package com.java2s; /* * Copyright (c) 2015-present, Facebook, Inc. * All rights reserved. * * This source code is licensed under the BSD-style license found in the * LICENSE file in the root directory of this source tree. An additional grant * of patent rights can be found in the PATENTS file in the same directory. */ import android.support.annotation.Nullable; public class Main { /** * Hash code is computed as value of polynomial whose coefficients are determined by hash codes * of objects passed as parameter to one of hashCode functions. More precisely: * hashCode(o1, o2, ..., on) = P[o1, o2, ..., on](X) = * X^n + o1.hashCode() * X ^ (n - 1) + o2.hashCode() * X ^ (n - 2) + ... + on.hashCode() * X ^ 0 * * <p> Constant X determines point at which polynomial is evaluated. */ private static final int X = 31; public static int hashCode(@Nullable Object o1) { return hashCode(o1 == null ? 0 : o1.hashCode()); } public static int hashCode(@Nullable Object o1, @Nullable Object o2) { return hashCode(o1 == null ? 0 : o1.hashCode(), o2 == null ? 0 : o2.hashCode()); } public static int hashCode(@Nullable Object o1, @Nullable Object o2, @Nullable Object o3) { return hashCode(o1 == null ? 0 : o1.hashCode(), o2 == null ? 0 : o2.hashCode(), o3 == null ? 0 : o3.hashCode()); } public static int hashCode(@Nullable Object o1, @Nullable Object o2, @Nullable Object o3, @Nullable Object o4) { return hashCode(o1 == null ? 0 : o1.hashCode(), o2 == null ? 0 : o2.hashCode(), o3 == null ? 0 : o3.hashCode(), o4 == null ? 0 : o4.hashCode()); } public static int hashCode(@Nullable Object o1, @Nullable Object o2, @Nullable Object o3, @Nullable Object o4, @Nullable Object o5) { return hashCode(o1 == null ? 0 : o1.hashCode(), o2 == null ? 0 : o2.hashCode(), o3 == null ? 0 : o3.hashCode(), o4 == null ? 0 : o4.hashCode(), o5 == null ? 0 : o5.hashCode()); } public static int hashCode(@Nullable Object o1, @Nullable Object o2, @Nullable Object o3, @Nullable Object o4, @Nullable Object o5, @Nullable Object o6) { return hashCode(o1 == null ? 0 : o1.hashCode(), o2 == null ? 0 : o2.hashCode(), o3 == null ? 0 : o3.hashCode(), o4 == null ? 0 : o4.hashCode(), o5 == null ? 0 : o5.hashCode(), o6 == null ? 0 : o6.hashCode()); } public static int hashCode(int i1) { int acc = X + i1; return acc; } public static int hashCode(int i1, int i2) { int acc = X + i1; acc = X * acc + i2; return acc; } public static int hashCode(int i1, int i2, int i3) { int acc = X + i1; acc = X * acc + i2; acc = X * acc + i3; return acc; } public static int hashCode(int i1, int i2, int i3, int i4) { int acc = X + i1; acc = X * acc + i2; acc = X * acc + i3; acc = X * acc + i4; return acc; } public static int hashCode(int i1, int i2, int i3, int i4, int i5) { int acc = X + i1; acc = X * acc + i2; acc = X * acc + i3; acc = X * acc + i4; acc = X * acc + i5; return acc; } public static int hashCode(int i1, int i2, int i3, int i4, int i5, int i6) { int acc = X + i1; acc = X * acc + i2; acc = X * acc + i3; acc = X * acc + i4; acc = X * acc + i5; acc = X * acc + i6; return acc; } }