如何在 Java 的大文本文件报告中 read/list 每页 30 行？
how to read/list 30 lines per page in a large text file report in Java?
我有一个 Java 问题涉及读取 txt 文件并从中提取数据。
这是一堆存储在 txt 报告文件中的二手车。他们有几个不同的批次出售。批次由 5 位邮政编码标识，后跟每个记录开头的邮政编码扩展。他们想要一份报告，列出所有批次的所有售出汽车。这是我想出的：
他们希望报告每页列出 30 辆汽车。每页都要有标题和页码。像这样：
我的问题是如何每页列出 30 辆汽车而不是全部列出（每页 30 辆汽车，带有标题和页码）？
这是我的源代码：
public class CustomerSale {
// Details of reports
private String zipCodeExtension;
private int customerNumber;
private String customerName;
private int purchaseDate;
private String make;
private int purchasePrice;
private int yearOfVehicle;
private int satisfactionRating;
// Create constructor argument
public CustomerSale(String zipCodeExtension, int customerNumber, String customerName,
int purchaseDate, String make, int purchasePrice,
int yearOfVehicle, int satisfactionRating) {
this.zipCodeExtension = zipCodeExtension;
this.customerNumber = customerNumber;
this.customerName = customerName;
this.purchaseDate = purchaseDate;
this.make = make;
this.purchasePrice = purchasePrice;
this.yearOfVehicle = yearOfVehicle;
this.satisfactionRating = satisfactionRating;
}
// Create getters and setters
public String getMake() {
return make;
}
public void setMake(String make) {
this.make = make;
}
public String getZipCodeExtension() {
return zipCodeExtension;
}
public void setZipCodeExtension(String zipCodeExtension) {
this.zipCodeExtension = zipCodeExtension;
}
public int getCustomerNumber() {
return customerNumber;
}
public void setCustomerNumber(int customerNumber) {
this.customerNumber = customerNumber;
}
public String getCustomerName() {
return customerName;
}
public void setCustomerName(String customerName) {
this.customerName = customerName;
}
public int getPurchaseDate() {
return purchaseDate;
}
public void setPurchaseDate(int purchaseDate) {
this.purchaseDate = purchaseDate;
}
public double getPurchasePrice() {
return purchasePrice;
}
public void setPurchasePrice(int purchasePrice) {
this.purchasePrice = purchasePrice;
}
public int getYearOfVehicle() {
return yearOfVehicle;
}
public void setYearOfVehicle(int yearOfVehicle) {
this.yearOfVehicle = yearOfVehicle;
}
public int getSatisfactionRating() {
return satisfactionRating;
}
public void setSatisfactionRating(int satisfactionRating) {
this.satisfactionRating = satisfactionRating;
}
}
import java.io.File;
import java.io.FileNotFoundException;
import java.text.DecimalFormat;
import java.util.Scanner;
public class ABCUsedCars {
public static void main(String[] args) throws FileNotFoundException {
File carsInfo = new File("src/custsale.txt");
Scanner carsScanner = new Scanner(carsInfo);
System.out.println(
"-------------------------------------------------ABC USED CARS----------------------------------------------------------------");
System.out.println(
"-------------------------------------------------------PAGE 1-----------------------------------------------------------------");
System.out.printf("%-19s%-15s%-21s%-15s%-20s%-17s%-12s%-20s\n", "|ZIP CODE-EXT|","|CUST No.|", "|CUSTOMER NAME|", "|DoP|",
"|MAKE|", "|PRICE|", "|YEAR|", "|RATE|");
System.out.println(
"------------------------------------------------------------------------------------------------------------------------------");
String format = "%-20s%-14s%-21s%-16s%-19s$%-17s%-14s%-20s\n";
DecimalFormat df = new DecimalFormat("#,#####");
while (carsScanner.hasNextLine()) {
String zipCodeExtension = carsScanner.nextLine();
int customerNumber = Integer.parseInt(carsScanner.nextLine());
String customerName = carsScanner.nextLine();
int purchaseDate = Integer.parseInt(carsScanner.nextLine());
String make = carsScanner.nextLine();
int purchasePrice = Integer.parseInt(carsScanner.nextLine());
int yearOfVehicle = Integer.parseInt(carsScanner.nextLine());
int satisfactionRating = Integer.parseInt(carsScanner.nextLine());
CustomerSale custsale = new CustomerSale(zipCodeExtension, customerNumber, customerName,
purchaseDate, make, purchasePrice, yearOfVehicle, satisfactionRating);
System.out.printf(format, custsale.getZipCodeExtension(), custsale.getCustomerNumber(),
custsale.getCustomerName(),custsale.getPurchaseDate(), custsale.getMake(),
df.format(custsale.getPurchasePrice()),custsale.getYearOfVehicle(),
custsale.getSatisfactionRating());
}
carsScanner.close();
}
}
这是文本文件报告：
46410-1234
1001
ALBERT, CARL T.
08252001
FORD
0255000
1991
2
46307-1201
1003
ANDREWS, ROBERT
08262001
CHEVROLET
0700000
1958
0
46423-2311
1008
ANZIO, RAFELINO
09012001
CHEVROLET
0456050
1978
0
46424-0121
1010
ASHLEY, WILLIAM B.
09022001
PIERCE-ARROW
1240000
1932
2
46375-3110
1015
ATKINSON, MARK
08272001
STUDEBAKER
0050000
1958
1
46405-1291
1025
AVERY, ALFRED A.
08292001
HUDSON
0230000
1954
1
46301-1234
1031
BEZZMEK, JENNIFER
08272001
FORD
0455000
1995
2
46303-1201
1033
BLAKE, DONALD
08292001
FORD
0722050
1989
1
46413-2311
1041
BLONDELL, BONNIE
09042001
CHEVROLET
0356050
1988
1
46404-0121
1045
BONADIO, JAMES
09032001
PIERCE-ARROW
1150000
1935
2
46307-3110
1055
BUCKO, ONIEDA
08282001
STUDEBAKER
0245000
1964
1
46410-1291
1056
BYMANN, FREDRICK
08292001
FORD
0330000
1994
1
46342-1234
1061
CALBERT, RONALD
09052001
FORD
0355000
1993
2
46307-1211
1063
CHELSEA, MARTHA S.
08302001
DODGE BROS.
0350000
1935
0
46410-2311
1067
CLAFLIN, WAYNE R.
09012001
CHEVROLET
0456050
1990
2
46410-0121
1070
COLE, CHARLES C.
09022001
PIERCE-ARROW
1050000
1929
2
46305-3111
1075
COLEMAN, THOMAS
08272001
STUDEBAKER
0167050
1961
1
46410-1221
1076
COLWELL, RICHARD L.
08292001
HUDSON
0430000
1940
1
46414-1231
1080
COOPER, JOHNATHAN
09052001
FORD
1256000
1996
2
46307-1201
2002
COREY, SARAH D.
08272001
CHEVROLET
0650050
1994
0
46421-2311
2004
CRACKLIN, GOODMAN
09012001
CHEVROLET
1456050
1996
0
46323-0121
2011
CRAWFORD, TIMOTHY
09012001
PIERCE-ARROW
1040000
1931
2
46315-3110
2012
CURRIE, RAYMOND
08282001
STUDEBAKER
0150025
1956
1
46425-1291
2024
CYBORG, IZORE M.
09052001
HUDSON
0130000
1949
1
46410-1234
2031
DALTON, DAVID P.
08252001
FORD
0234000
1990
2
46307-1201
2043
DAVIES, RALPH O.
08262001
CHEVROLET
0333000
1989
0
46423-2311
2048
DENNICK, DONNA
09012001
CHEVROLET
0656025
1995
0
46424-0121
2050
DERBIN, DEANNA
09022001
PIERCE-ARROW
1640025
1937
2
46375-3110
2065
DONNEHUE, PHILLIP
09042001
STUDEBAKER
0054000
1966
1
46405-1291
2085
DOPPLER, RADAR O.
08302001
HUDSON
0311000
1951
1
46310-1234
2091
DUNLOP, RITA
08252001
FORD
1450045
1996
2
46303-1201
3003
DYKES, CYNTHIA
08262001
FORD
0410050
1987
1
46413-2311
3011
EATON, ESTER B.
09012001
CHEVROLET
1356050
1996
0
46404-0121
3015
EFFLEY, BAILY
09022001
PIERCE-ARROW
1446045
1933
2
46307-3110
3025
EGGERTON, AMANDA
08292001
STUDEBAKER
0335000
1965
1
46410-1291
3026
EPPLEY, DAVID
08282001
FORD
0414000
1995
1
46342-1234
3031
ERKLE, ROSA
09032001
FORD
0355020
1993
2
46307-1211
3043
FARNSWORTH, WESLEY
09052001
DODGE BROS.
1150000
1996
0
46410-2311
3047
FLANNERY, JAMES
09012001
CHEVROLET
0450050
1992
0
46410-0121
3050
FOREMAN, OTTO J.
09022001
PIERCE-ARROW
0940000
1927
2
46305-3111
3055
FOWLER, KATHLEEN
08272001
STUDEBAKER
0267050
1964
1
46410-1221
3056
FURNACE, DAVID
08292001
HUDSON
0530000
1948
1
46414-1231
3061
GALLAGHER, CLARENCE
0904200
1FORD
1006000
1992
2
46307-1201
3062
GENNERRO, TONY S.
08302001
CHEVROLET
0320050
1989
0
46421-2311
3066
GOEBEL, NANCY K.
09022001
CHEVROLET
0643050
1990
0
46323-0121
3072
GUNTHER, FREDERICK
09032001
PIERCE-ARROW
1260000
1930
2
46315-3110
3080
HAINES, MARSHALL
08292001
STUDEBAKER
02500251
959
1
46425-1291
3094
HANCOCK, JONATHON
09032001
HUDSON
0330000
1953
1
46423-2311
3098
HARTNETT, ROBERTO
09052001
CHEVROLET
0326040
1988
0
46424-0121
4005
HENNING, SONIA
09052001
PIERCE-ARROW
1305000
1928
2
46375-3110
4009
HORNSBY, ROGERS
08252001
STUDEBAKER
0167500
1962
1
46405-1291
4012
HYATT, JANET F.
08302001
HUDSON
0155000
1951
1
46301-1234
4021
IDZIOR, RAYMOND
09012001
FORD
1460000
1996
2
46303-1201
4022
JENNINGS, WILLIAM
08262001
FORD
0612040
1992
1
46410-2311
4024
JOHNSON, JACK
09032001
CHEVROLET
0256050
1985
0
46404-0121
4032
KULKA, ROBERT C.
09042001
PIERCE-ARROW
0970000
1934
2
46307-3110
4035
KURTZ, DONALD
08302001
STUDEBAKER
0345000
1966
1
46410-1291
4038
LEVANDOWSKI, JILL
08282001
DODGE BROS.
0430000
1988
1
46342-1234
4044
METZ, ARNOLD E.
09012001
FORD
1323000
1996
2
46307-1211
4046
NORRIS, CHARLES S.
09052001
CHEVROLET
0844000
1992
0
46410-2311
4047
NOWAKOWSKI, ALFRED
09012001
DODGE BROS.
0656050
1994
1
46410-0121
4053
O'BOYLE, NIEL
09032001
PIERCE-ARROW
1550000
1938
2
46305-3111
4056
O'BRIAN, PATRICK
08302001
STUDEBAKER
0347050
1962
1
46410-1221
4059
PATTERSON, LENNI R.
08292001
HUDSON
0250000
1946
1
46414-1231
4061
PERRY, SHAMUS
09052001
FORD
0895000
1994
2
46307-1201
4066
REED, ROBERT B.
08272001
CHEVROLET
0740050
1996
0
46421-2311
4067
RODRIGUEZ, ALONZO
09052001
DODGE BROS.
1050050
1995
0
46323-0121
4073
SANCHEZ, HENRY
09012001
PIERCE-ARROW
0830000
1925
2
46315-3110
4081
SWARTZ, HECTOR
08282001
STUDEBAKER
0075025
1954
1
46301-1234
4084
TORREZ, MARTIN
0827200
1FORD
0565000
1994
2
46303-1201
4090
TUTTLE, MARK
08292001
FORD
0710050
1996
1
46413-2311
4094
WARNER, JACK
09042001
CHEVROLET
0856050
1996
0
46404-0121
4115
YACKLEY, YOURTO
09042001
PIERCE-ARROW
1000000
1930
2
正如我在评论中所述，您需要计算已处理的汽车数量，并在遇到 30 辆汽车的倍数时打印新页面 headers。
首先，我建议将您的 header 打印语句移动到一个单独的方法中，例如printPageHeader(int pageNumber)。然后像这样改变你的循环：
final int pageSize = 30;
int carCounter = 0;
while (carsScanner.hasNextLine()) {
if( carCounter % pageSize == 0 ) {
printPageHeader( carCounter / pageSize + 1 );
}
//read car lines here
//print your car
System.out.printf(format, ... );
//count the car
carCounter++;
}
我有一个 Java 问题涉及读取 txt 文件并从中提取数据。
这是一堆存储在 txt 报告文件中的二手车。他们有几个不同的批次出售。批次由 5 位邮政编码标识，后跟每个记录开头的邮政编码扩展。他们想要一份报告，列出所有批次的所有售出汽车。这是我想出的：
他们希望报告每页列出 30 辆汽车。每页都要有标题和页码。像这样：
我的问题是如何每页列出 30 辆汽车而不是全部列出（每页 30 辆汽车，带有标题和页码）？
这是我的源代码：
public class CustomerSale {
// Details of reports
private String zipCodeExtension;
private int customerNumber;
private String customerName;
private int purchaseDate;
private String make;
private int purchasePrice;
private int yearOfVehicle;
private int satisfactionRating;
// Create constructor argument
public CustomerSale(String zipCodeExtension, int customerNumber, String customerName,
int purchaseDate, String make, int purchasePrice,
int yearOfVehicle, int satisfactionRating) {
this.zipCodeExtension = zipCodeExtension;
this.customerNumber = customerNumber;
this.customerName = customerName;
this.purchaseDate = purchaseDate;
this.make = make;
this.purchasePrice = purchasePrice;
this.yearOfVehicle = yearOfVehicle;
this.satisfactionRating = satisfactionRating;
}
// Create getters and setters
public String getMake() {
return make;
}
public void setMake(String make) {
this.make = make;
}
public String getZipCodeExtension() {
return zipCodeExtension;
}
public void setZipCodeExtension(String zipCodeExtension) {
this.zipCodeExtension = zipCodeExtension;
}
public int getCustomerNumber() {
return customerNumber;
}
public void setCustomerNumber(int customerNumber) {
this.customerNumber = customerNumber;
}
public String getCustomerName() {
return customerName;
}
public void setCustomerName(String customerName) {
this.customerName = customerName;
}
public int getPurchaseDate() {
return purchaseDate;
}
public void setPurchaseDate(int purchaseDate) {
this.purchaseDate = purchaseDate;
}
public double getPurchasePrice() {
return purchasePrice;
}
public void setPurchasePrice(int purchasePrice) {
this.purchasePrice = purchasePrice;
}
public int getYearOfVehicle() {
return yearOfVehicle;
}
public void setYearOfVehicle(int yearOfVehicle) {
this.yearOfVehicle = yearOfVehicle;
}
public int getSatisfactionRating() {
return satisfactionRating;
}
public void setSatisfactionRating(int satisfactionRating) {
this.satisfactionRating = satisfactionRating;
}
}
import java.io.File;
import java.io.FileNotFoundException;
import java.text.DecimalFormat;
import java.util.Scanner;
public class ABCUsedCars {
public static void main(String[] args) throws FileNotFoundException {
File carsInfo = new File("src/custsale.txt");
Scanner carsScanner = new Scanner(carsInfo);
System.out.println(
"-------------------------------------------------ABC USED CARS----------------------------------------------------------------");
System.out.println(
"-------------------------------------------------------PAGE 1-----------------------------------------------------------------");
System.out.printf("%-19s%-15s%-21s%-15s%-20s%-17s%-12s%-20s\n", "|ZIP CODE-EXT|","|CUST No.|", "|CUSTOMER NAME|", "|DoP|",
"|MAKE|", "|PRICE|", "|YEAR|", "|RATE|");
System.out.println(
"------------------------------------------------------------------------------------------------------------------------------");
String format = "%-20s%-14s%-21s%-16s%-19s$%-17s%-14s%-20s\n";
DecimalFormat df = new DecimalFormat("#,#####");
while (carsScanner.hasNextLine()) {
String zipCodeExtension = carsScanner.nextLine();
int customerNumber = Integer.parseInt(carsScanner.nextLine());
String customerName = carsScanner.nextLine();
int purchaseDate = Integer.parseInt(carsScanner.nextLine());
String make = carsScanner.nextLine();
int purchasePrice = Integer.parseInt(carsScanner.nextLine());
int yearOfVehicle = Integer.parseInt(carsScanner.nextLine());
int satisfactionRating = Integer.parseInt(carsScanner.nextLine());
CustomerSale custsale = new CustomerSale(zipCodeExtension, customerNumber, customerName,
purchaseDate, make, purchasePrice, yearOfVehicle, satisfactionRating);
System.out.printf(format, custsale.getZipCodeExtension(), custsale.getCustomerNumber(),
custsale.getCustomerName(),custsale.getPurchaseDate(), custsale.getMake(),
df.format(custsale.getPurchasePrice()),custsale.getYearOfVehicle(),
custsale.getSatisfactionRating());
}
carsScanner.close();
}
}
这是文本文件报告：
46410-1234
1001
ALBERT, CARL T.
08252001
FORD
0255000
1991
2
46307-1201
1003
ANDREWS, ROBERT
08262001
CHEVROLET
0700000
1958
0
46423-2311
1008
ANZIO, RAFELINO
09012001
CHEVROLET
0456050
1978
0
46424-0121
1010
ASHLEY, WILLIAM B.
09022001
PIERCE-ARROW
1240000
1932
2
46375-3110
1015
ATKINSON, MARK
08272001
STUDEBAKER
0050000
1958
1
46405-1291
1025
AVERY, ALFRED A.
08292001
HUDSON
0230000
1954
1
46301-1234
1031
BEZZMEK, JENNIFER
08272001
FORD
0455000
1995
2
46303-1201
1033
BLAKE, DONALD
08292001
FORD
0722050
1989
1
46413-2311
1041
BLONDELL, BONNIE
09042001
CHEVROLET
0356050
1988
1
46404-0121
1045
BONADIO, JAMES
09032001
PIERCE-ARROW
1150000
1935
2
46307-3110
1055
BUCKO, ONIEDA
08282001
STUDEBAKER
0245000
1964
1
46410-1291
1056
BYMANN, FREDRICK
08292001
FORD
0330000
1994
1
46342-1234
1061
CALBERT, RONALD
09052001
FORD
0355000
1993
2
46307-1211
1063
CHELSEA, MARTHA S.
08302001
DODGE BROS.
0350000
1935
0
46410-2311
1067
CLAFLIN, WAYNE R.
09012001
CHEVROLET
0456050
1990
2
46410-0121
1070
COLE, CHARLES C.
09022001
PIERCE-ARROW
1050000
1929
2
46305-3111
1075
COLEMAN, THOMAS
08272001
STUDEBAKER
0167050
1961
1
46410-1221
1076
COLWELL, RICHARD L.
08292001
HUDSON
0430000
1940
1
46414-1231
1080
COOPER, JOHNATHAN
09052001
FORD
1256000
1996
2
46307-1201
2002
COREY, SARAH D.
08272001
CHEVROLET
0650050
1994
0
46421-2311
2004
CRACKLIN, GOODMAN
09012001
CHEVROLET
1456050
1996
0
46323-0121
2011
CRAWFORD, TIMOTHY
09012001
PIERCE-ARROW
1040000
1931
2
46315-3110
2012
CURRIE, RAYMOND
08282001
STUDEBAKER
0150025
1956
1
46425-1291
2024
CYBORG, IZORE M.
09052001
HUDSON
0130000
1949
1
46410-1234
2031
DALTON, DAVID P.
08252001
FORD
0234000
1990
2
46307-1201
2043
DAVIES, RALPH O.
08262001
CHEVROLET
0333000
1989
0
46423-2311
2048
DENNICK, DONNA
09012001
CHEVROLET
0656025
1995
0
46424-0121
2050
DERBIN, DEANNA
09022001
PIERCE-ARROW
1640025
1937
2
46375-3110
2065
DONNEHUE, PHILLIP
09042001
STUDEBAKER
0054000
1966
1
46405-1291
2085
DOPPLER, RADAR O.
08302001
HUDSON
0311000
1951
1
46310-1234
2091
DUNLOP, RITA
08252001
FORD
1450045
1996
2
46303-1201
3003
DYKES, CYNTHIA
08262001
FORD
0410050
1987
1
46413-2311
3011
EATON, ESTER B.
09012001
CHEVROLET
1356050
1996
0
46404-0121
3015
EFFLEY, BAILY
09022001
PIERCE-ARROW
1446045
1933
2
46307-3110
3025
EGGERTON, AMANDA
08292001
STUDEBAKER
0335000
1965
1
46410-1291
3026
EPPLEY, DAVID
08282001
FORD
0414000
1995
1
46342-1234
3031
ERKLE, ROSA
09032001
FORD
0355020
1993
2
46307-1211
3043
FARNSWORTH, WESLEY
09052001
DODGE BROS.
1150000
1996
0
46410-2311
3047
FLANNERY, JAMES
09012001
CHEVROLET
0450050
1992
0
46410-0121
3050
FOREMAN, OTTO J.
09022001
PIERCE-ARROW
0940000
1927
2
46305-3111
3055
FOWLER, KATHLEEN
08272001
STUDEBAKER
0267050
1964
1
46410-1221
3056
FURNACE, DAVID
08292001
HUDSON
0530000
1948
1
46414-1231
3061
GALLAGHER, CLARENCE
0904200
1FORD
1006000
1992
2
46307-1201
3062
GENNERRO, TONY S.
08302001
CHEVROLET
0320050
1989
0
46421-2311
3066
GOEBEL, NANCY K.
09022001
CHEVROLET
0643050
1990
0
46323-0121
3072
GUNTHER, FREDERICK
09032001
PIERCE-ARROW
1260000
1930
2
46315-3110
3080
HAINES, MARSHALL
08292001
STUDEBAKER
02500251
959
1
46425-1291
3094
HANCOCK, JONATHON
09032001
HUDSON
0330000
1953
1
46423-2311
3098
HARTNETT, ROBERTO
09052001
CHEVROLET
0326040
1988
0
46424-0121
4005
HENNING, SONIA
09052001
PIERCE-ARROW
1305000
1928
2
46375-3110
4009
HORNSBY, ROGERS
08252001
STUDEBAKER
0167500
1962
1
46405-1291
4012
HYATT, JANET F.
08302001
HUDSON
0155000
1951
1
46301-1234
4021
IDZIOR, RAYMOND
09012001
FORD
1460000
1996
2
46303-1201
4022
JENNINGS, WILLIAM
08262001
FORD
0612040
1992
1
46410-2311
4024
JOHNSON, JACK
09032001
CHEVROLET
0256050
1985
0
46404-0121
4032
KULKA, ROBERT C.
09042001
PIERCE-ARROW
0970000
1934
2
46307-3110
4035
KURTZ, DONALD
08302001
STUDEBAKER
0345000
1966
1
46410-1291
4038
LEVANDOWSKI, JILL
08282001
DODGE BROS.
0430000
1988
1
46342-1234
4044
METZ, ARNOLD E.
09012001
FORD
1323000
1996
2
46307-1211
4046
NORRIS, CHARLES S.
09052001
CHEVROLET
0844000
1992
0
46410-2311
4047
NOWAKOWSKI, ALFRED
09012001
DODGE BROS.
0656050
1994
1
46410-0121
4053
O'BOYLE, NIEL
09032001
PIERCE-ARROW
1550000
1938
2
46305-3111
4056
O'BRIAN, PATRICK
08302001
STUDEBAKER
0347050
1962
1
46410-1221
4059
PATTERSON, LENNI R.
08292001
HUDSON
0250000
1946
1
46414-1231
4061
PERRY, SHAMUS
09052001
FORD
0895000
1994
2
46307-1201
4066
REED, ROBERT B.
08272001
CHEVROLET
0740050
1996
0
46421-2311
4067
RODRIGUEZ, ALONZO
09052001
DODGE BROS.
1050050
1995
0
46323-0121
4073
SANCHEZ, HENRY
09012001
PIERCE-ARROW
0830000
1925
2
46315-3110
4081
SWARTZ, HECTOR
08282001
STUDEBAKER
0075025
1954
1
46301-1234
4084
TORREZ, MARTIN
0827200
1FORD
0565000
1994
2
46303-1201
4090
TUTTLE, MARK
08292001
FORD
0710050
1996
1
46413-2311
4094
WARNER, JACK
09042001
CHEVROLET
0856050
1996
0
46404-0121
4115
YACKLEY, YOURTO
09042001
PIERCE-ARROW
1000000
1930
2
正如我在评论中所述，您需要计算已处理的汽车数量，并在遇到 30 辆汽车的倍数时打印新页面 headers。
首先，我建议将您的 header 打印语句移动到一个单独的方法中，例如printPageHeader(int pageNumber)。然后像这样改变你的循环：
final int pageSize = 30;
int carCounter = 0;
while (carsScanner.hasNextLine()) {
if( carCounter % pageSize == 0 ) {
printPageHeader( carCounter / pageSize + 1 );
}
//read car lines here
//print your car
System.out.printf(format, ... );
//count the car
carCounter++;
}