Java高效过滤Map的键值对方法

Map<string integer> map = new HashMap();
map.put("Apple", 10);
map.put("Banana", 20);
map.put("Avocado", 30);
map.put("Cherry", 40);

Map<string integer> filteredByKey = map.entrySet()
    .stream()
    .filter(entry -> entry.getKey().startsWith("A"))
    .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));

// 结果：{Apple=10, Avocado=30}
</string></string>

Map<string integer> filteredByValue = map.entrySet()
    .stream()
    .filter(entry -> entry.getValue() > 15)
    .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));

// 结果：{Banana=20, Avocado=30, Cherry=40}
</string>

Map<string integer> filteredByKeyAndValue = map.entrySet()
    .stream()
    .filter(entry -> entry.getKey().startsWith("A") && entry.getValue() > 15)
    .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));

// 结果：{Avocado=30}
</string>

.collect(Collectors.toMap(
    Map.Entry::getKey,
    Map.Entry::getValue,
    (v1, v2) -> v1 // 冲突时保留第一个值
));