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新增将集合或数组里的元素填充到 Map 中的相关方法。

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zhouxy108 2023-06-03 23:58:53 +08:00
parent b732578e6d
commit fe49fbba58
1 changed files with 110 additions and 0 deletions
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src/main/java/xyz/zhouxy/plusone/commons/util/MoreCollections.java
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@ -1,18 +1,128 @@
package xyz.zhouxy.plusone.commons.util;
import java.util.Arrays;
import java.util.Collection;
import java.util.Comparator;
import java.util.HashMap;
import java.util.Map;
import java.util.TreeMap;
import java.util.function.Function;
import javax.annotation.Nullable;
import xyz.zhouxy.plusone.commons.collection.SafeConcurrentHashMap;
public class MoreCollections {
// isEmpty
public static boolean isEmpty(@Nullable Collection<?> collection) {
return collection == null || collection.isEmpty();
}
public static boolean isEmpty(@Nullable Map<?, ?> map) {
return map == null || map.isEmpty();
}
// isNotEmpty
public static boolean isNotEmpty(@Nullable Collection<?> collection) {
return collection != null && !collection.isEmpty();
}
public static boolean isNotEmpty(@Nullable Map<?, ?> map) {
return map != null && !map.isEmpty();
}
// Collection -> Map
public static <K, V> HashMap<K, V> toHashMap(Iterable<V> c, Function<? super V, K> keyGenerator,
int initialCapacity) {
HashMap<K, V> map = new HashMap<>(initialCapacity);
fillIntoEmptyMap(map, c, keyGenerator);
return map;
}
public static <K, V> HashMap<K, V> toHashMap(Collection<V> c, Function<? super V, K> keyGenerator) {
return toHashMap(c, keyGenerator, c.size());
}
public static <K, V> SafeConcurrentHashMap<K, V> toConcurrentHashMap(Iterable<V> c,
Function<? super V, K> keyGenerator,
int initialCapacity) {
SafeConcurrentHashMap<K, V> map = new SafeConcurrentHashMap<>(initialCapacity);
fillIntoEmptyMap(map, c, keyGenerator);
return map;
}
public static <K, V> SafeConcurrentHashMap<K, V> toConcurrentHashMap(Collection<V> c,
Function<? super V, K> keyGenerator) {
return toConcurrentHashMap(c, keyGenerator, c.size());
}
public static <K, V> TreeMap<K, V> toTreeMap(Iterable<V> c, Function<? super V, K> keyGenerator) {
TreeMap<K, V> map = new TreeMap<>();
fillIntoEmptyMap(map, c, keyGenerator);
return map;
}
public static <K, V> TreeMap<K, V> toTreeMap(Iterable<V> c, Function<? super V, K> keyGenerator,
Comparator<? super K> keycComparator) {
TreeMap<K, V> map = new TreeMap<>(keycComparator);
fillIntoEmptyMap(map, c, keyGenerator);
return map;
}
public static <K, V> void fillIntoEmptyMap(Map<K, ? super V> map, Iterable<V> c,
Function<? super V, K> keyGenerator) {
if (map == null || !map.isEmpty()) {
throw new IllegalArgumentException("The map should be empty.");
}
for (V v : c) {
map.put(keyGenerator.apply(v), v);
}
}
// array -> map
public static <K, V> HashMap<K, V> toHashMap(V[] c, Function<? super V, K> keyGenerator, int initialCapacity) {
HashMap<K, V> map = new HashMap<>(initialCapacity);
fillIntoEmptyMap(map, c, keyGenerator);
return map;
}
public static <K, V> HashMap<K, V> toHashMap(V[] c, Function<? super V, K> keyGenerator) {
return toHashMap(c, keyGenerator, c.length);
}
public static <K, V> SafeConcurrentHashMap<K, V> toConcurrentHashMap(V[] c, Function<? super V, K> keyGenerator,
int initialCapacity) {
SafeConcurrentHashMap<K, V> map = new SafeConcurrentHashMap<>(initialCapacity);
fillIntoEmptyMap(map, c, keyGenerator);
return map;
}
public static <K, V> SafeConcurrentHashMap<K, V> toConcurrentHashMap(V[] c, Function<? super V, K> keyGenerator) {
return toConcurrentHashMap(c, keyGenerator, c.length);
}
public static <K, V> TreeMap<K, V> toTreeMap(V[] c, Function<? super V, K> keyGenerator) {
TreeMap<K, V> map = new TreeMap<>();
fillIntoEmptyMap(map, c, keyGenerator);
return map;
}
public static <K, V> TreeMap<K, V> toTreeMap(V[] c, Function<? super V, K> keyGenerator,
Comparator<? super K> keycComparator) {
TreeMap<K, V> map = new TreeMap<>(keycComparator);
fillIntoEmptyMap(map, c, keyGenerator);
return map;
}
public static <K, V> void fillIntoEmptyMap(Map<K, ? super V> map, V[] c, Function<? super V, K> keyGenerator) {
fillIntoEmptyMap(map, Arrays.asList(c), keyGenerator);
}
private MoreCollections() {
throw new IllegalStateException("Utility class");
}