大数据在医疗领域的应用有哪些？请举例说明。

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

public class DiseasePredictionSystem {

    private Map<String, Integer> patientHealthData;

    public DiseasePredictionSystem() {
        patientHealthData = new HashMap<>();
    }

    /**
     * 添加患者健康数据
     * @param patientId 患者ID
     * @param data 健康数据
     */
    public void addPatientHealthData(String patientId, int data) {
        patientHealthData.put(patientId, data);
    }

    /**
     * 预测患病风险
     * @param patientId 患者ID
     * @return 患病风险
     */
    public String predictDiseaseRisk(String patientId) {
        if (!patientHealthData.containsKey(patientId)) {
            return "Insufficient data";
        }
        int healthData = patientHealthData.get(patientId);
        if (healthData > 100) {
            return "High risk";
        } else if (healthData > 50) {
            return "Medium risk";
        } else {
            return "Low risk";
        }
    }

    public static void main(String[] args) {
        DiseasePredictionSystem predictionSystem = new DiseasePredictionSystem();
        predictionSystem.addPatientHealthData("patient1", 80);
        predictionSystem.addPatientHealthData("patient2", 120);
        String riskLevel1 = predictionSystem.predictDiseaseRisk("patient1");
        String riskLevel2 = predictionSystem.predictDiseaseRisk("patient2");
        System.out.println("Patient1 disease risk level: " + riskLevel1);
        System.out.println("Patient2 disease risk level: " + riskLevel2);
    }
}