Clone an Object/Arraylist in java.

Assets.java

import java.util.Date;
import java.util.List;

public class Assets {
	public String formatId;

	public String formatName;

	public String assetId;

	public String uploadedby;

	public String uploadedById;

	public Date uploadedon;

	public String size;

	public String formatStatus;

	public TransactionVO distributionData;

	public Boolean singleFile;

	public String ePubCheckerToolVersion;

	public String ePubCheckerStatus;

	public List<FileDetails> fileDetails;

	public Assets() {

	}

  // This is very necessary ...   
	public Assets(Assets assets) {
		this.formatId = assets.formatId;
		this.formatName = assets.formatName;
		this.assetId = assets.assetId;
		this.uploadedby = assets.uploadedby;
		this.uploadedById = assets.uploadedById;
		this.uploadedon = assets.uploadedon;
		this.size = assets.size;
		this.formatStatus = assets.formatStatus;
		this.distributionData = assets.distributionData;
		this.singleFile = assets.singleFile;
		this.ePubCheckerToolVersion = assets.ePubCheckerToolVersion;
		this.ePubCheckerStatus = assets.ePubCheckerStatus;
		this.fileDetails = assets.fileDetails;
	}

	public Assets(String formatId, String formatName, String assetId, String uploadedby, String uploadedById,
			Date uploadedon, String size, String formatStatus, TransactionVO distributionData, Boolean singleFile,
			String ePubCheckerToolVersion, String ePubCheckerStatus, List<FileDetails> fileDetails) {
		super();
		this.formatId = formatId;
		this.formatName = formatName;
		this.assetId = assetId;
		this.uploadedby = uploadedby;
		this.uploadedById = uploadedById;
		this.uploadedon = uploadedon;
		this.size = size;
		this.formatStatus = formatStatus;
		this.distributionData = distributionData;
		this.singleFile = singleFile;
		this.ePubCheckerToolVersion = ePubCheckerToolVersion;
		this.ePubCheckerStatus = ePubCheckerStatus;
		this.fileDetails = fileDetails;
	}

	public List<FileDetails> getFileDetails() {
		return fileDetails;
	}

	public void setFileDetails(List<FileDetails> fileDetails) {
		this.fileDetails = fileDetails;
	}

	public String getAssetId() {
		return assetId;
	}

	public void setAssetId(String assetId) {
		this.assetId = assetId;
	}

	public String getFormatId() {
		return formatId;
	}

	public void setFormatId(String formatId) {
		this.formatId = formatId;
	}

	public String getSize() {
		return size;
	}

	public void setSize(String size) {
		this.size = size;
	}

	public String getFormatName() {
		return formatName;
	}

	public void setFormatName(String formatName) {
		this.formatName = formatName;
	}

	public String getUploadedby() {
		return uploadedby;
	}

	public void setUploadedby(String uploadedby) {
		this.uploadedby = uploadedby;
	}

	public String getUploadedById() {
		return uploadedById;
	}

	public void setUploadedById(String uploadedById) {
		this.uploadedById = uploadedById;
	}

	public Date getUploadedon() {
		return uploadedon;
	}

	public void setUploadedon(Date uploadedon) {
		this.uploadedon = uploadedon;
	}

	public String getFormatStatus() {
		return formatStatus;
	}

	public void setFormatStatus(String formatStatus) {
		this.formatStatus = formatStatus;
	}

	public TransactionVO getDistributionData() {
		return distributionData;
	}

	public void setDistributionData(TransactionVO distributionData) {
		this.distributionData = distributionData;
	}

	public Boolean getSingleFile() {
		return singleFile;
	}

	public void setSingleFile(Boolean singleFile) {
		this.singleFile = singleFile;
	}

	public String getePubCheckerToolVersion() {
		return ePubCheckerToolVersion;
	}

	public void setePubCheckerToolVersion(String ePubCheckerToolVersion) {
		this.ePubCheckerToolVersion = ePubCheckerToolVersion;
	}

	public String getePubCheckerStatus() {
		return ePubCheckerStatus;
	}

	public void setePubCheckerStatus(String ePubCheckerStatus) {
		this.ePubCheckerStatus = ePubCheckerStatus;
	}

}

Copier.java

List<Assets> formats = <LIST WITH LOTS OF DATA>

// newFormatList will be deep cloned and changes to this list will not be reflected to formats list ...
List<Assets> newFormatList = formats.stream().map(Assets::new).collect(Collectors.toList());
for (Assets format : newFormatList) {
  format.setFileDetails(null);
}