fuck code.

Main.java

import java.util.Map;
import java.util.HashMap;

public class Main {
    private Map<String, String> map;

    public Main() {
        Map<String, String> map = new HashMap<String, String>();
        map.put("a", "123");
        map.put("b", "d");
        map.put("c", "456");

        System.out.println(getValueAsInt("a"));
        System.out.println(getValueAsInt("b"));
        System.out.println(getValueAsInt("c"));
    }

    public int getValueAsInt(String key) {
        if(map.get(key) == null){
            return -1;
        } else {
            int res;
            try{
                res = Integer.parseInt(map.get(key));
            } catch(NumberFormatException e) {
                e.printStackTrace();
                res = -1;
            }
            return res;
        }
    }

    public static void main(String args[]){
        new Main();
    }
}

import java.util.Arrays;
import java.util.Map;
import java.util.stream.Collectors;

public class Java9 {
	private final Map<String, Integer> map = Map.of("a", "123", "b", "d", "c", "456")
			.entrySet().stream()
			.collect(Collectors.toMap(Map.Entry::getKey, entry -> {
				try {
					return Integer.parseInt(entry.getValue());
				} catch (NumberFormatException e) {
					return -1;
				}
			}));

	public int getValueAsInt(String key) {
		return map.getOrDefault(key, -1);
	}

	public static void main(String... args) {
		new Java9().print(args);
	}

	private void print(String... keys) {
		Arrays.stream(keys).forEach(key -> System.out.println(getValueAsInt(key)));
	}
}

import java.util.Arrays;
import java.util.Map;

// https://gist.github.com/gakuzzzz/9f35617943decf2893ea
import static jp.t2v.lab.syntax.MapStreamSyntax.entryToMap;
import static jp.t2v.lab.syntax.MapStreamSyntax.values;

public class Java9 {
	private final Map<String, Integer> map = Map.of("a", "123", "b", "d", "c", "456")
			.entrySet().stream()
			.map(values(s -> {
				try {
					return Integer.parseInt(s);
				} catch (NumberFormatException e) {
					return -1;
				}
			})).collect(entryToMap());

	public int getValueAsInt(String key) {
		return map.getOrDefault(key, -1);
	}

	public static void main(String... args) {
		new Java9().print(args);
	}

	private void print(String... keys) {
//		Arrays.stream(keys).forEach(key -> System.out.println(getValueAsInt(key)));
		Arrays.stream(keys).mapToInt(this::getValueAsInt).forEach(System.out::println);
	}
}