TreeMap<String,String> map = new TreeMap<String,String>();用于两个字符串比较/链接值。但我有一个问题。我需要链接/比较三个字符串我该怎么办？
我的示例输入是：
input #1
id number: 5
name: jomar
course: computer science
input#2
id number: 3
name: karen
course: IT
当我按ID号对其进行排序并打印时，它应该是这样的：
ID num name course
3 karen IT
5 jomar computer science
这是我的代码，我希望有人可以改进我的代码：
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Scanner;
import java.util.TreeMap;
public class studentreport3 {
static Scanner j = new Scanner(System.in);
static Scanner a = new Scanner(System.in);
public static void main(String[] args) {
List<String> mapmap = new ArrayList<String>();
List<String> studentnumberA = new ArrayList<String>();
List<String> studentnameA = new ArrayList<String>();
List<String> courseA = new ArrayList<String>();
List<Double> prelimA = new ArrayList<Double>();
List<Double> midtermA = new ArrayList<Double>();
List<Double> finalsA = new ArrayList<Double>();
double prelim,midterm,finals;
String menu,menu2;
String transaction=null,transaction2=null,transaction3=null;
String studentname=null,course=null,studentnumber = null;
do{
System.out.print("\t\t\tDi Natuto University \n\t\t\t Pililla,Rizal \n\n\t\t\t Main Menu \n\t\tSM\tStudent Maintenance \n\t\tSR\tStudent Report \n\t\tSGR\tStudent Grade Report \n\t\tX\tExit \n\n\t\tProcess? ");
menu=j.nextLine();
if(menu.equals("x")||menu.equals("X")){
System.exit(0);
}
if(menu.equals("SM")||menu.equals("sm")){
do{
TreeMap<String,String[]> map = new TreeMap<String,String[]>();
System.out.print("Student Number: ");
studentnumber=j.nextLine();
studentnumberA.add(studentnumber);
System.out.print("Student Name: ");
studentname=a.nextLine();
studentnameA.add(studentname);
System.out.print("Course : ");
course=j.nextLine();
courseA.add(course);
map.put(studentnumber, new String[]{studentname, course});
System.out.print("Prelim Grade: ");
prelim=j.nextDouble();
prelimA.add(prelim);
System.out.print("Midterm Grade: ");
midterm=j.nextDouble();
midtermA.add(midterm);
System.out.print("Finals Grade: ");
finals=j.nextDouble();
finalsA.add(finals);
j.nextLine();
System.out.println("Continue? (Y/N): ");
transaction=a.nextLine();
} while(transaction.equalsIgnoreCase("Y"));
}
if(menu.equalsIgnoreCase("sr")){
do{
System.out.println("\t\t\tDi Natuto University \n\t\t\t Pililla,Rizal \n\n\t\t\tStudent Summary Report \n\n" +
"\t\t\tSNo\tStudent no. \n\t\t\tSna\tStudent Name \n\t\t\tCo\tCourse \n\t\t\tX\tExit \n\n\t\tProcess? ");
menu2=j.nextLine();
System.out.println("\n");
if(menu2.equalsIgnoreCase("X")){
System.exit(0);
}
if(menu2.equalsIgnoreCase("sno")){
String[] array = studentnumberA.toArray(new String[studentnumberA.size()]);
String[] array2 = studentnameA.toArray(new String[studentnameA.size()]);
String[] array3 = courseA.toArray(new String[courseA.size()]);
String [][] storeAllArray = {array,array2,array3};
TreeMap<String,String> map = new TreeMap<String,String>();
TreeMap<String,String> map2 = new TreeMap<String,String>();
System.out.println("\t\t\t\tDi Natuto University \n\t\t\t\t Pililla,Rizal \n\n\t\t\t\tStudent Summary Report \n\n\t\t\tStudent no."+" Student Name"+"\t\tCourse ");
for(int i=0;i<array.length;i++){
map2.put(array[i], array3[i]);
map.put(array[i], array2[i]);
}
for (String key : map.keySet())
System.out.println("\t\t\t"+key + "\t\t " + map.get(key));
for (String key2 : map2.keySet())
System.out.println("\t\t\t\t\t\t\t\t"+map2.get(key2));
System.out.println("\n");
}
if(menu2.equalsIgnoreCase("sna")){
String[] array = studentnumberA.toArray(new String[studentnumberA.size()]);
String[] array2 = studentnameA.toArray(new String[studentnameA.size()]);
String[] array3 = courseA.toArray(new String[courseA.size()]);
String [][][] storeAllArray = {{array},{array2},{array3}};
TreeMap<String,String> map = new TreeMap<String,String>();
TreeMap<String,String> map2 = new TreeMap<String,String>();
System.out.println("\t\t\t\tDi Natuto University \n\t\t\t\t Pililla,Rizal \n\n\t\t\t\tStudent Summary Report \n\n\t\t\tStudent no."+" Student Name"+"\tCourse ");
for(int i=0;i<array.length;i++){
String [][] Array11= {{array[i]},{array2[i]},{array3[i]}};
String [][] Array12= {{array[i]},{array2[i]}};
map2.put(array2[i], array3[i]);
map.put(array2[i], array[i]);
}
for (String key : map.keySet())
System.out.println("\t\t\t"+map.get(key)+ "\t\t " + key+"\t\t");
for (String key2 : map2.keySet())
System.out.println("\t\t\t\t\t\t\t"+map2.get(key2));
}
if(menu2.equalsIgnoreCase("co")){
String[] array = studentnumberA.toArray(new String[studentnumberA.size()]);
String[] array2 = studentnameA.toArray(new String[studentnameA.size()]);
String[] array3 = courseA.toArray(new String[courseA.size()]);
TreeMap<String,String> map = new TreeMap<String,String>();
TreeMap<String,String> map2 = new TreeMap<String,String>();
System.out.println("\t\t\t\tDi Natuto University \n\t\t\t\t Pililla,Rizal \n\n\t\t\t\tStudent Summary Report \n\n\t\t\tStudent no."+" Student Name"+"\tCourse ");
for(int i=0;i<array.length;i++){
int count=0;
String [][][] storeAllArray = {{array},{array2},{array3}};
String [][] Array11= {{array[i]},{array2[i]},{array3[i]}};
String [][] Array12= {{array[i]},{array2[i]}};
map2.put(array3[i], array2[i]);
map.put(array3[i], array[i]);
}
for (String key : map.keySet())
System.out.println("\t\t\t"+map.get(key)+ "\t\t " +"\t\t"+key);
for (String key2 : map2.keySet())
System.out.println("\t\t\t\t\t"+map2.get(key2));
System.out.println("\n");
}
System.out.print("Continue? (Y/N)");
transaction2=j.nextLine();
}while(transaction2.equalsIgnoreCase("Y"));
}
if(menu.equalsIgnoreCase("sgr")){
String[] array = studentnumberA.toArray(new String[studentnumberA.size()]);
String[] array2 = studentnameA.toArray(new String[studentnameA.size()]);
String[] array3 = courseA.toArray(new String[courseA.size()]);
Double[] array4 = prelimA.toArray(new Double[prelimA.size()]);
Double[] array5 = midtermA.toArray(new Double[midtermA.size()]);
Double[] array6 = finalsA.toArray(new Double[finalsA.size()]);
String [][] storeAllArray = {array,array2,array3};
System.out.println("\t\t\t\tDi Natuto University \n\t\t\t\t Pililla,Rizal \n\n\t\t\t\tStudent Grade Report \n\n\t\t\tStudent no."+" Student Name"+"\tCourse"+"\t\t\tAverage");
for(int i=0;i<array.length;i++){
Double sum = (array4[i]+array5[i]+array6[i])/3;
System.out.println("\t\t\t"+array[i]+"\t\t "+array2[i]+"\t\t"+array3[i]+"\t\t\t"+sum);
}
System.out.print("\n\n\t\t\tM\t\tMain Menu\n\t\t\tX\t\tExit\nChoice: ");
transaction3=j.nextLine();
if(transaction3.equalsIgnoreCase("X")){
System.out.print("\t\t\t\tDi Natuto University \n\t\t\t\t Pililla,Rizal \n\n\t\t\t\tThank you for using Di Natuto Grading System...");
System.exit(0);
}
}
}while(transaction.equalsIgnoreCase("N")||transaction2.equalsIgnoreCase("N")||transaction3.equalsIgnoreCase("N"));
}
}
答案 0 :(得分：0)
这取决于您希望如何访问数据。如果您想使用id作为参考，您可以执行以下操作：
TreeMap<String,String[]> map = new TreeMap<String,String[]>();
String[]可以保存名称和课程字符串，String将设置为ID。然后要访问它，你会做类似的事情：
String name = map.get(id)[0];
String course = map.get(id)[1];
另外，要添加数据，您可以：
String id = "5";
String name = "jomar";
String course = "computer science";
map.put(id, new String[]{name, course});
答案 1 :(得分：0)
如果您定义如下所示的TreeMap，则为是，TreeMap中只有两个字符串，即键和映射值
TreeMap<String,String> map = new TreeMap<String,String>();
但是如果你将TreeMap定义为
TreeMap<String,Student> map = new TreeMap<String,Student>();
public class Student{ // you might need to implement Comparable interface
private int id;
private String name;
private String course;
//getter and setter and other methods
}
您甚至可以比较三个以上的字符串。我希望你会找到自己的方式。
如果您只需要排序信息，例如学生，列表也是不错的选择
List<Student> list = new ArrayList<Student>();
Collections.sort(list); //you will have to implement comparable interface on Student class and do it with id on overrided compareTo() method