为什么这个java语句跳不出while循环

import java.util.*;

public class Test {
private static String m;
private static String f;
public static void toclass(int a1){
if(a1<200){
System.out.println("Total cholesterol:"+a1+" DESIRABLE");
}
else if(a1>=240){
System.out.println("Total cholesterol:"+a1+" HIGH");
}
else{
System.out.println("Total cholesterol:"+a1+" BORDERLINE HIGH");
}
}
public static void HDLclass(int b,String s){
if(b>=60){
System.out.println("HDL"+b+" HIGH");
}
else if(s==m){
if(b<40){
System.out.println("HDL"+b+" LOW");
}
else{
System.out.println("HDL"+b+" AVERAGE");
}
}
else{
if(b<50){
System.out.println("HDL"+b+" LOW");
}
else{
System.out.println("HDL"+b+" AVERAGE");
}
}
}
public static void triclass(int c){
if(c<150){
System.out.println("Triglycerides: "+c+" DESIRABLE");
}
else if(c>=200){
System.out.println("Triglycerides: "+c+" HIGH");
}
else{
System.out.println("Triglycerides: "+c+" BORDERLINE HIGH");
}
}
public static void ratioclass(double d){
if(d<=3.3){
System.out.println("Ratio:"+d+" DECREASED RISK");
}
else if(d>=5.1){
System.out.println("Ratio:"+d+" INCREASED RISK");
}
else{
System.out.println("Ratio:"+d+" AVERAGE RISK");
}
}
public static void main(String args[]){
int LDL;
double ratio;
boolean flag=false;
System.out.println("Enter patient ID");
Scanner sca=new Scanner(System.in);
String s=sca.next();
while(true){
System.out.println("Enter sex (m/f) for patient "+s+":");
Scanner a=new Scanner(System.in);
String sex=a.next();
System.out.println("Enter total cholesterol, HDL and triglycerides for patient "+s+":");
Scanner in=new Scanner(System.in);
int total_cholesterol=in.nextInt();
Scanner in1=new Scanner(System.in);
int HDL=in1.nextInt();
Scanner in2=new Scanner(System.in);
int triglycerides=in2.nextInt();
LDL=(total_cholesterol-HDL-triglycerides)/5;
ratio=total_cholesterol/HDL;
Math.round(ratio);
System.out.println("Lipid Profile for Patient "+s+":");
toclass(total_cholesterol);
HDLclass(HDL, sex);
triclass(triglycerides);
ratioclass(ratio);
System.out.println("Enter patient ID");
Scanner sca1=new Scanner(System.in);

if(sca1.hasNext()){
break;
}
};

}
}

你都 while(true){ 真 会一直循环
System.out.println("Enter sex (m/f) for patient "+s+":");

因为你在while ((ch = fin.read()) != '\r') {//判断：不断读取下一个字符，直到用户输入换行 这个中，ch=fin.read()这个是不断的读取文件中的内容，直到内容结束。