MapToIntTest.java

package com.annimon.stream.streamtests;

import com.annimon.stream.Stream;
import com.annimon.stream.function.ToIntFunction;
import org.junit.Test;
import static com.annimon.stream.test.hamcrest.IntStreamMatcher.assertElements;
import static org.hamcrest.Matchers.arrayContaining;

public final class MapToIntTest {

    @Test
    public void testMapToInt() {
        final ToIntFunction<String> stringToSquareInt = new ToIntFunction<String>() {
            @Override
            public int applyAsInt(String t) {
                final String str = t.substring(1, t.length() - 1);
                final int value = Integer.parseInt(str);
                return value * value;
            }
        };

        Stream.of("[2]", "[3]", "[4]", "[8]", "[25]")
                .mapToInt(stringToSquareInt)
                .custom(assertElements(arrayContaining(
                        4, 9, 16, 64, 625
                )));
    }
}