com.github.vendigo.acetest.utils.Utils Maven / Gradle / Ivy

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package com.github.vendigo.acetest.utils;

import lombok.AccessLevel;
import lombok.NoArgsConstructor;

import java.util.Collection;
import java.util.Iterator;
import java.util.function.Supplier;

@NoArgsConstructor(access = AccessLevel.PRIVATE)
public class Utils {

    public static  T getOnlyElement(Collection collection) {
        Iterator iterator = collection.iterator();
        T first = iterator.next();
        if (!iterator.hasNext()) {
            return first;
        }

        StringBuilder sb = new StringBuilder().append("expected one element but was: <").append(first);
        for (int i = 0; i < 4 && iterator.hasNext(); i++) {
            sb.append(", ").append(iterator.next());
        }
        if (iterator.hasNext()) {
            sb.append(", ...");
        }
        sb.append('>');

        throw new IllegalArgumentException(sb.toString());
    }

    public static  T getFirst(Collection collection, T defaultValue) {
        Iterator iterator = collection.iterator();
        return iterator.hasNext() ? iterator.next() : defaultValue;
    }

    public static  T getFirst(Collection collection, Supplier exception) {
        Iterator iterator = collection.iterator();
        if (iterator.hasNext()) {
            return iterator.next();
        } else {
            throw exception.get();
        }
    }
}