Effective Java - Item 2. コンストラクタにパラメータが多い場合はビルダーを検討する

// 페라미터의 의미가 알 수가 없다
StreamInfo info1 = new StreamInfo(200, 150, true, false);
StreamInfo info2 = new StreamInfo(200, 150, false);

// JavaBeans 패턴
StreamInfo info = new StreamInfo();
info.setWidth(200);
info.setHeight(150);
info.setCaption(true);
info.setProgressive(false);

// Builder 패턴으로 생성할 수 있도록 한 StreamInfo 클래스
public class StreamInfo {
    private final int width;
    private final int height;
    private final boolean hasCaption;
    private final boolean isProgressive;

    /** To create an instance of StreamInfo, use Builder#build() instead. */
    private StreamInfo(Builder builder) {
        width = builder.width;
        height = builder.height;
        hasCaption = builder.hasCaption;
        isProgressive = builder.isProgressive;
    }

    public int getWidth() { return width; }
    public int getHeight() { return height; }
    public boolean hasCaption() { return hasCaption; }
    public boolean isProgressive() { return isProgressive; }

    public static class Builder {
        private int width;
        private int height;
        private boolean hasCaption;
        private boolean isProgressive;

        public Builder setWidth(int width) {
            this.width = width;
            return this;
        }

        public Builder setHeight(int height) {
            this.height = height;
            return this;
        }

        public Builder setCaption(boolean hasCaption) {
            this.hasCaption = hasCaption;
            return this;
        }

        public Builder setProgressive(boolean isProgressive) {
            this.isProgressive = isProgressive;
            return this;
        }

        public StreamInfo build() {
            // If necessary fields have not been set yet,
            // IllegalStateException can be thrown here.
            return new StreamInfo(this);
        }
    }
}

StreamInfo info = new StreamInfo.Builder().setWidth(200).setHeight(150)
        .setCaption(true).setProgressive(false).build();