java 的 linq,不要再写令人讨厌的 for 了!

时间:2023-03-09 04:17:55
java 的 linq,不要再写令人讨厌的 for 了!
package com.ly.linq;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator; public class Enm {
public static <T> ArrayList<T> notNull(Iterable<T> source) {
return where(source, new Pre<T>() {
@Override
public boolean check(T t) {
return t != null;
}
});
} public static <T> ArrayList<T> where(T[] ts, Pre<T> mapper) {
return where(toList(ts), mapper);
} public static <T> ArrayList<T> where(Iterable<T> source, Pre<T> mapper) {
ArrayList<T> r = new ArrayList<T>();
for (T t : source) {
if (mapper.check(t)) {
r.add(t);
}
}
return r;
} public static <T> String toString(T[] source, Object s) {
return toString(toList(source), s);
} public static <T> String toString(T[] source, Object s, FuncT<T, String> mapper) {
return toString(toList(source), s, mapper);
} public static <T> String toString(Iterable<T> source, Object s) {
return toString(source, s, null);
} public static <T> String toString(Iterable<T> source, Object spliter, FuncT<T, String> mapper) {
String s = spliter == null ? "" : spliter.toString();
StringBuilder sb = new StringBuilder();
for (T ti : source) {
String str = mapper == null ? ti.toString() : mapper.get(ti);
sb.append(str + s);
}
if (sb.length() > 0) {
sb.setLength(sb.length() - s.length());
return sb.toString();
} else {
return "";
}
} public static <T, TKey, TValue> HashMap<TKey, TValue> toHashMap(T[] ts, FuncT<T, Pair<TKey, TValue>> pair) {
return toHashMap(toList(ts), pair);
} public static <T, TKey, TValue> HashMap<TKey, TValue> toHashMap(Iterable<T> source, FuncT<T, Pair<TKey, TValue>> pair) {
HashMap<TKey, TValue> r = new HashMap<TKey, TValue>();
for (T t : source) {
Pair<TKey, TValue> p = pair.get(t);
r.put(p.getKey(), p.getValue());
}
return r;
} public static <T> ArrayList<T> toList(Iterable<T> source) {
ArrayList<T> r = new ArrayList<T>();
for (T t : source) {
r.add(t);
}
return r;
} public static <T> ArrayList<T> toList(T[] ts) {
ArrayList<T> r = new ArrayList<T>();
for (T t : ts) {
r.add(t);
}
return r;
} public static <T> ArrayList<T> except(Iterable<T> it0, Iterable<T> it1) {
ArrayList<T> r = new ArrayList<T>();
for (T t : it0) {
if (!r.contains(t)) {
r.add(t);
}
}
for (int i = r.size() - 1; i > -1; i--) {
T t = r.get(i);
if (contains(it1, t)) {
r.remove(t);
}
}
return r;
} public static <T> ArrayList<T> union(Iterable<T> it0, Iterable<T> it1) {
ArrayList<T> r = new ArrayList<T>();
for (T t : it0) {
if (!r.contains(t)) {
r.add(t);
}
}
for (T t : it1) {
if (!r.contains(t)) {
r.add(t);
}
}
return r;
} public static <T> ArrayList<T> intersect(Iterable<T> it0, Iterable<T> it1) {
ArrayList<T> r = new ArrayList<T>();
for (T t0 : it0) {
for (T t1 : it1) {
if (t0 == null) {
if (t1 == null) {
if (!r.contains(t0)) {
r.add(t0);
}
}
} else {
if (t0.equals(t1)) {
if (!r.contains(t0)) {
r.add(t0);
}
}
}
}
}
return r;
} public static <T0, T1, TOut> ArrayList<TOut> intersect(Class<TOut> outCls, Iterable<T0> it0, Iterable<T1> it1, FuncT<T0, TOut> mapper0, FuncT<T1, TOut> mapper1) {
ArrayList<TOut> r = new ArrayList<TOut>();
for (T0 t0 : it0) {
TOut t0out = mapper0.get(t0);
for (T1 t1 : it1) {
TOut t1out = mapper1.get(t1);
if (t0out == null) {
if (t1out == null) {
if (!r.contains(t0out)) {
r.add(null);
}
}
} else {
if (t0out.equals(t1out)) {
if (!r.contains(t0out)) {
r.add(t0out);
}
}
}
}
}
return r;
} public static <T> boolean existsIn(T t, T... ts) {
for (T t2 : ts) {
if (t.equals(t2)) {
return true;
}
}
return false;
} public static <T> boolean contains(Iterable<T> source, T target) {
for (T t : source) {
if (t == null) {
if (target == null) {
return true;
}
} else {
if (t.equals(target)) {
return true;
}
}
}
return false;
} public static <T> boolean any(Pre<T> pre, T t, T... ts) {
if (pre.check(t)) {
return true;
}
return any(toList(ts), pre);
} public static <T> boolean any(T[] ts, Pre<T> pre) {
return any(toList(ts), pre);
} public static <T> boolean any(Iterable<T> source, Pre<T> pre) {
for (T i : source) {
if (pre.check(i)) {
return true;
}
}
return false;
} public static <T> ArrayList<T> sort(ArrayList<T> source, FuncT<T, Integer> mapper) {
int[] indexes = sortIndexes(source, mapper);
ArrayList<T> r = new ArrayList<T>();
for (int i : indexes) {
r.add(source.get(i));
}
return r;
} public static <T> int[] sortIndexes(Iterable<T> source, FuncT<T, Integer> mapper) {
ArrayList<Integer> ints = new ArrayList<Integer>();
Iterator<T> it = source.iterator();
while (it.hasNext()) {
Integer integer = mapper.get(it.next());
ints.add(integer);
}
int[] r = new int[ints.size()];
for (int i = 0; i < r.length; i++) {
r[i] = ints.get(i);
}
return sortIndexes(r);
} public static <T> int[] sortIndexes(T[] source, FuncT<T, Integer> mapper) {
int[] ints = new int[source.length];
for (int i = 0; i < source.length; i++) {
ints[i] = mapper.get(source[i]);
}
return sortIndexes(ints);
} public static int[] sortIndexes(int[] source) {
ArrayList<Integer> decre = new ArrayList<Integer>();
for (int i : source) {
decre.add(i);
}
ArrayList<Integer> incre = new ArrayList<Integer>();
while (incre.size() < source.length) {
int s = 0;
int v = decre.get(0);
for (int i = 1; i < decre.size(); i++) {
int e = decre.get(i);
if (e < v) {
s = i;
v = e;
}
}
decre.remove(s);
for (int i = 0; i < source.length; i++) {
if (source[i] != v || incre.contains(i)) {
continue;
}
incre.add(i);
break;
}
}
int[] r = new int[incre.size()];
for (int i = 0; i < incre.size(); i++) {
r[i] = incre.get(i);
}
return r;
} public static <TIn, TOut> ArrayList<TOut> select(TIn[] source, FuncT<TIn, TOut> mapper) {
return select(toList(source), mapper);
} public static <TIn, TOut> ArrayList<TOut> select(Iterable<TIn> source, FuncT<TIn, TOut> mapper) {
ArrayList<TOut> r = new ArrayList<TOut>();
for (TIn ti : source) {
r.add(mapper.get(ti));
}
return r;
}
}