Multiple entries with same key: 1=1 and 1=1

发布时间：2024-11-12 23:14

异常描述

Exception in thread “main” java.lang.IllegalArgumentException: Multiple entries with same key: 1=1 and 1=1

异常场景

测试环境提测一个功能马上要验收完毕，突然提示下单失败，和测试各种解释与本次更新无关；但测试担心是本次更新的内容影响了整体流程拒绝发送验证报告；查看日志发现，异常信息类似上面，Bean中的一个属性字段重复了，还是作为Map的Key值重复的，Map的Key值是Set，自动过滤重复数据，为何报错

异常模拟

// import com.google.common.base.Function; // import com.google.common.collect.Maps; public static void main(String[] args) { List<Integer> integerList = Arrays.asList(1,2,3,4,5,1,2,3,4); Map<Integer, Integer> map = Maps.uniqueIndex(integerList, new Function<Integer, Integer>() { @Override public Integer apply(Integer input) { return input.intValue(); } }); System.out.println(map); }123456789101112

源码分析

// 方法调用 public static <K, V> ImmutableMap<K, V> uniqueIndex(Iterable<V> values, Function<? super V, K> keyFunction) { return uniqueIndex(values.iterator(), keyFunction); } // 将集合中的数据放入 TerminalEntry<K, V>[] entries; public static <K, V> ImmutableMap<K, V> uniqueIndex(Iterator<V> values, Function<? super V, K> keyFunction) { Preconditions.checkNotNull(keyFunction); // 初始化 TerminalEntry<K, V>[] entries; Builder builder = ImmutableMap.builder(); while(values.hasNext()) { V value = values.next(); builder.put(keyFunction.apply(value), value); } return builder.build(); } // size 大于 1 进入 default 方法 public ImmutableMap<K, V> build() { switch(this.size) { case 0: return ImmutableBiMap.of(); case 1: return ImmutableBiMap.of(this.entries[0].getKey(), this.entries[0].getValue()); default: return new RegularImmutableMap(this.size, this.entries); } } RegularImmutableMap(int size, TerminalEntry<?, ?>[] theEntries) { this.entries = this.createEntryArray(size); int tableSize = Hashing.closedTableSize(size, 1.2D); this.table = this.createEntryArray(tableSize); this.mask = tableSize - 1; for(int entryIndex = 0; entryIndex < size; ++entryIndex) { TerminalEntry<K, V> entry = theEntries[entryIndex]; K key = entry.getKey(); // 判断是否有重复数据的方法 // 将每个KEY取hash值与数组长度-1 取余 // 保证数组中每个下标的位置上都有数据 // 如果对新的KEY值Hash后在数组的该下标位置取到数据 // 代表该数据已经存在 int tableIndex = Hashing.smear(key.hashCode()) & this.mask; ImmutableMapEntry<K, V> existing = this.table[tableIndex]; ImmutableMapEntry<K, V> newEntry = existing == null ? entry : new RegularImmutableMap.NonTerminalMapEntry(entry, existing); this.table[tableIndex] = (ImmutableMapEntry)newEntry; this.entries[entryIndex] = (ImmutableMapEntry)newEntry; this.checkNoConflictInBucket(key, (ImmutableMapEntry)newEntry, existing); } } private void checkNoConflictInBucket(K key, ImmutableMapEntry<K, V> entry, ImmutableMapEntry<K, V> bucketHead) { // 当已存在数据不空时调用此方法 while(bucketHead != null) { checkNoConflict(!key.equals(bucketHead.getKey()), "key", entry, bucketHead); bucketHead = bucketHead.getNextInKeyBucket(); } } // 抛出相应异常 static void checkNoConflict(boolean safe, String conflictDescription, Entry<?, ?> entry1, Entry<?, ?> entry2) { if (!safe) { String var4 = String.valueOf(String.valueOf(conflictDescription)); String var5 = String.valueOf(String.valueOf(entry1)); String var6 = String.valueOf(String.valueOf(entry2)); throw new IllegalArgumentException((new StringBuilder(34 + var4.length() + var5.length() + var6.length())).append("Multiple entries with same ").append(var4).append(": ").append(var5).append(" and ").append(var6).toString()); } }

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