JsonObjectBuilder

JsonObjectBuilder.java

package com.foxydeal.fdcinput;

/**
 * Created by fschulz on 17.12.2015.
 */
public class JsonObjectBuilder {

    public static final String QUOTE = "\"";
    private StringBuilder jsonString;
    private int propertyCounter = 0;

    public JsonObjectBuilder() {
        this.jsonString = new StringBuilder();
        jsonString.append("{");
    }

    public static JsonObjectBuilder json() {
        return new JsonObjectBuilder();
    }

    public String end() {
        String s = jsonString.append("}").toString();
        jsonString = new StringBuilder();
        return s;
    }

    public JsonObjectBuilder startObject(String fieldName) {
        addCommaIfMoreThanOneElement();
        jsonString.append(QUOTE).append(fieldName).append(QUOTE).append(":{");
        return this;
    }

    public JsonObjectBuilder endObject() {
        jsonString.append("}");
        return this;
    }

    public JsonObjectBuilder property(String fieldName, String value) {
        addCommaIfMoreThanOneElement();
        jsonString.append(QUOTE).append(fieldName).append(QUOTE).append(":").append(QUOTE).append(value).append(QUOTE);
        return this;
    }

    public JsonObjectBuilder property(String fieldName, Number value) {
        addCommaIfMoreThanOneElement();
        jsonString.append(QUOTE).append(fieldName).append(QUOTE).append(":").append(value);
        return this;
    }

    private void addCommaIfMoreThanOneElement() {
        if (propertyCounter > 0) {
            jsonString.append(",");
        }
        propertyCounter++;
    }

    public JsonArrayBuilder array(String fieldName) {
        return new JsonArrayBuilder(this, fieldName);
    }

    public class JsonArrayBuilder {

        private JsonObjectBuilder jsonObjectBuilder;
        int counter = 0;

        public JsonArrayBuilder(JsonObjectBuilder jsonObjectBuilder, String arrayName) {
            this.jsonObjectBuilder = jsonObjectBuilder;
            jsonObjectBuilder.jsonString.append(QUOTE).append(arrayName).append(QUOTE).append(":[");
        }

        public JsonArrayBuilder add(Number number) {
            addCommaIfMoreThanOneElement();
            jsonString.append(number);

            return this;
        }

        public JsonArrayBuilder add(String string) {
            addCommaIfMoreThanOneElement();
            jsonString.append(QUOTE).append(string).append(QUOTE);
            return this;
        }

        private void addCommaIfMoreThanOneElement() {
            if (counter > 0) {
                jsonString.append(",");
            }
            counter++;
        }

        public JsonObjectBuilder arrayEnd() {
            jsonString.append("]");
            return jsonObjectBuilder;
        }
    }
}

JsonObjectBuilderTest.java

package com.foxydeal.fdcinput;

import org.junit.Before;
import org.junit.Test;

import static com.foxydeal.fdcinput.JsonObjectBuilder.json;
import static org.hamcrest.core.Is.is;
import static org.junit.Assert.assertThat;

/**
 * Created by fschulz on 17.12.2015.
 */
public class JsonObjectBuilderTest {

    @Before
    public void setUp() throws Exception {

    }

    @Test
    public void testEmptyJson() {
        String json = json().end();
        assertThat(json, is("{}"));
    }

    @Test
    public void testSingleStringProperty() {
        String json = json().property("test", "test").end();
        assertThat(json, is("{\"test\":\"test\"}"));
    }

    @Test
    public void testMultipleProperties() {
        String json = json()
                .property("test", "test")
                .property("test2", 3)
                .property("test3", 3.3)
                .end();
        assertThat(json, is("{\"test\":\"test\",\"test2\":3,\"test3\":3.3}"));
    }

    @Test
    public void testSingleDoubleProperty() {
        String json = json().property("test", 1.12355123).end();
        assertThat(json, is("{\"test\":1.12355123}"));
    }

    @Test
    public void testSingleIntegerProperty() {
        String json = json().property("test", 1).end();
        assertThat(json, is("{\"test\":1}"));
    }

    @Test
    public void testArrayIntegerProperty() {
        String json = json().array("array").add(1).add(2).add(3).arrayEnd().end();
        assertThat(json, is("{\"array\":[1,2,3]}"));
    }

    @Test
    public void testArrayDoubleProperty() {
        String json = json().array("array").add(1.1).add(2.2).add(3.3).arrayEnd().end();
        assertThat(json, is("{\"array\":[1.1,2.2,3.3]}"));
    }

    @Test
    public void testArrayStringProperty() {
        String json = json().array("array").add("bla1").add("bla2").add("bla3").arrayEnd().end();
        assertThat(json, is("{\"array\":[\"bla1\",\"bla2\",\"bla3\"]}"));
    }

    @Test
    public void testEmptySubObject() {
        String json = json().startObject("test").endObject().end();
        assertThat(json, is("{\"test\":{}}"));
    }

    @Test
    public void testSubObject() {
        String json = json().startObject("test").property("inner_test", "bla").endObject().end();
        assertThat(json, is("{\"test\":{\"inner_test\":\"bla\"}}"));
    }

}