温度单位转换java程序问题
这个程序部分的运行结果是
Enter a number to choose one of the following options:
1.Convert temperatures one at a time.
2.Convert temperature from a list of values in a .txt file.
3.End the program
1
You select 1
Enter temperature:
f
Please enter a number!
Enter temperature:
c
Please enter a number!
Enter temperature:
20
Enter scale:
f
Enter scale to convert to (F, C, K, R):
c
122.0 is -6.666666666666666c
Would you like to do another conversion? (y/n):
可以看到我输入温度是20，但打印出来是122.0，自动加上了102，还不带单位，有人帮忙看看是为什么吗？
import java.util.Scanner;
import java.io.*;
/**
* TemperatureConversion provides static methods that allow temperatures to be
* converted between 4 scales: celsius, fahrenheit, kelvin, rankine.
* Name: Xiangcheng Ding
* UniqueID: DINGX11
* Instructor: Dr. Deepak Dawar
* Course number and section: CSE271 Lab1
*
* @author Jill Courte
* @modified Laurie Werner
* @version 1.1
*/
public class TemperatureConversion
{
public final static char FAHRENHEIT = 'F';
public final static char CELSIUS = 'C';
public final static char KELVIN = 'K';
public final static char RANKINE = 'R';
/**
* Given a double value in fahrenheit and a scale, converts the value to that scale.
* @param value - the fahrenheit value to be converted
* @param scale - the target scale - one of 'F', 'C', 'K', 'R'
*/
public double fahrenheitToOther (double value, char scale) {
double newValue = 0;
if(scale == FAHRENHEIT || scale== 'f'){
}else if(scale == CELSIUS || scale == 'c'){
newValue=(value-32)/1.8;
} else if (scale == KELVIN || scale == 'k') {
newValue=(value-32)/1.8+273.15;
} else if (scale == RANKINE || scale == 'r') {
newValue=value+459.67;
}else {
return 0.0;
}
return newValue;
}
/**
* Given a double value in celsius and a scale, converts the value to that scale.
* @param value - the celsius value to be converted
* @param scale - the target scale - one of 'F', 'C', 'K', 'R'
*/
public double celsiusToOther (double value, char scale) {
double newValue=0;
if (scale == CELSIUS || scale == 'c') {
} else if (scale == FAHRENHEIT || scale == 'f') {
newValue = (value * 1.8) + 32;
} else if (scale == KELVIN || scale == 'k') {
newValue = value + 273.15;
} else if (scale == RANKINE || scale == 'r') {
newValue = value * 1.8 + 32 + 459.67;
} else {
return 0.0;
}
return newValue;
}
/**
* Given a double value in kelvin and a scale, converts the value to that scale.
* @param value - the kelvin value to be converted
* @param scale - the target scale - one of 'F', 'C', 'K', 'R'
*/
public double kelvinToOther (double value, char scale) {
double newValue=0;
if (scale == KELVIN || scale == 'k') {
} else if (scale == FAHRENHEIT || scale == 'f') {
newValue = (value - 273.15) * 1.8 + 32;
} else if (scale == CELSIUS || scale == 'c') {
newValue = value - 273.15;
} else if (scale == RANKINE || scale == 'r') {
newValue = value * 1.8;
} else {
return 0.0;
}
return newValue;
}
/**
* Given a double value in rankine and a scale, converts the value to that scale.
* @param value - the rankine value to be converted
* @param scale - the target scale - one of 'F', 'C', 'K', 'R'
*/
public double rankineToOther (double value, char scale) {
double newValue=0;
if (scale == RANKINE || scale == 'r') {
} else if (scale == FAHRENHEIT || scale == 'f') {
newValue = value-459.76;
} else if (scale == KELVIN || scale == 'k') {
newValue = value/1.8;
} else if (scale == CELSIUS || scale == 'c') {
newValue = (value-32-459.67)/1.8;
} else {
return 0.0;
}
return newValue;
}
/**
* Given a double value and its associated scale, and a new scale,
* converts the given value from the original scale to the new scale.
* Each scale shoud be one of 'F', 'C', 'K', 'R' (fahranheit, celsius, kelvin, rankine)
* @param originalValue - the value to be converted
* @param originalScale - the scale of the original value
* @param newScale - the target scale
*/
public double doConversion (double originalValue, char originalScale, char newScale)
{
double newValue = 0.0;
if (originalScale == CELSIUS || originalScale == 'c') {
newValue = celsiusToOther(originalValue, newScale);
} else if (originalScale == KELVIN || originalScale == 'k') {
newValue = kelvinToOther(originalValue, newScale);
} else if (originalScale == FAHRENHEIT || originalScale == 'f') {
newValue = fahrenheitToOther(originalValue, newScale);
} else if (originalScale == RANKINE || originalScale == 'r') {
newValue = rankineToOther(originalValue, newScale);
}
return newValue;
}
public static void main (String [] args)
{
boolean repeat, repeat2=true, repeat3=true, repeat4 = true;
double temp = 0;
char scale;
while(repeat2){
repeat = true;
int option;
Scanner in = new Scanner(System.in);
System.out.println("Enter a number to choose one of the following options:\n" +
"\n" +
"1.Convert temperatures one at a time.\n" +
"2.Convert temperature from a list of values in a .txt file.\n" +
"3.End the program");
while(repeat){
if (in.hasNextInt()) {
option = in.nextInt();
if (option == 1) {
System.out.println("You select 1");
do {
boolean isNotDoble = true;
while (isNotDoble) {
in = new Scanner(System.in);
System.out.println("Enter temperature: ");
if (in.hasNextDouble()) {
temp = in.nextDouble();
isNotDoble = false;
} else {
System.out.println("Please enter a number!");
}
}
in = new Scanner(System.in);
System.out.println("Enter scale: ");
scale = in.next().charAt(0);
in = new Scanner(System.in);
System.out.println("Enter scale to convert to (F, C, K, R): ");
char newScale = in.next().charAt(0);
TemperatureConversion Conversion = new TemperatureConversion();
double newTemp = Conversion.doConversion(temp, scale, newScale);
if (newTemp == 0.0) {
System.out.println("Please enter proper scales!");
} else {
System.out.println(temp + scale + " is " + newTemp + newScale);
repeat3 = false;
}
} while (repeat3);
in = new Scanner(System.in);
System.out.println("Would you like to do another conversion? (y/n): ");
String yes = in.next();
if (yes.equals("y") || yes.equals("Y")) {
break;
} else if (yes.equals("n") || yes.equals("N")) {
repeat = false;
} else {
System.out.println("Please enter 'y' or 'n'.");
}
} else if (option == 2) {
try {
String fileName;
in = new Scanner(System.in);
System.out.print("Please enter a file name: ");
fileName = in.next();
File inputFile = new File(fileName);
in = new Scanner(inputFile);
double[] temps = new double[0];
char[] scales = new char[0];
char[] newScales = new char[0];
int i = 0, j = 0, k = 0;
while(in.hasNextDouble()){
temps[i] = in.nextDouble();
i++;
}
in.close();
in = new Scanner(inputFile);
while (in.hasNext()){
scales[j]=in.next().charAt(0);
in.next();
j++;
}
in.close();
in = new Scanner(inputFile);
while(in.hasNext()){
in.next();
newScales[k] = in.next().charAt(0);
k++;
}
in.close();
TemperatureConversion conversion = new TemperatureConversion();
double[] newTemps = new double[0];
for(int a = 0; a <= i; a++){
newTemps[a] = conversion.doConversion(temps[a],scales[a],newScales[a]);
if (newTemps[a] == 0){
System.out.println("error invalid original scale specified " + scales[a]);
}else{
System.out.println(temps[a] + scales[a] + " is " + newTemps[a] + newScales[a]);
}
}
}catch (IOException exception){
exception.printStackTrace();
}
} else if (option == 3) {
System.out.println("Goodbye");
repeat = false;
repeat2 = false;
} else {
System.out.println("Please enter 1, 2, or 3!");
System.out.println("");
repeat = false;
}
} else{
System.out.println("Please enter 1, 2, or 3!");
System.out.println("");
repeat = false;
}
}
}
}
}
问题出在这段代码块中：
while (in.hasNextDouble()){
temps[i] = in.nextDouble();
i++;
}
你在使用数组temps之前没有为其分配内存空间，因此会导致数组越界异常。你需要在读取文件之前定义一个足够大的数组，以存储读取的温度值。
同样的问题也存在于scales和newScales数组的使用中。
解决方法是在读取文件之前，为这些数组分配正确的大小，例如：
double[] temps = new double[10];
char[] scales = new char[10];
char[] newScales = new char[10];
请根据你的需要选择适当的数组大小。在这个例子中，我将数组大小设置为10。你可以根据实际情况进行调整。
如果以上回答对您有所帮助，点击一下采纳该答案～谢谢
- 问题
- 解决
System.out.println(temp+"" + scale + " is " + newTemp + newScale);
- 原理
在Java中，char类型和double类型是可以自动相加的。当char类型和double类型进行相加运算时，char类型会被隐式地转换为其对应的Unicode编码值，然后与double类型进行相加。这是因为char类型在内部表示为Unicode编码值，而double类型是一种浮点数类型。
例如，如果有以下代码：
char c = 'A';
double d = 3.14;
System.out.println(c + d);
输出将会是：
68.14
- 如果解决您的问题，希望采纳一下啦
引用 皆我百晓生 小程序回复内容作答：
你好！根据你提供的代码，问题出现在doConversion方法中。在该方法中，当originalScale为'C'或'c'时，newValue的值没有被赋值，因此默认为0.0。这就导致返回的newValue为0.0，而不是正确的转换结果。
为了解决这个问题，你应该修改doConversion方法中每个条件分支的初始化newValue的方式。这样，无论originalScale的值是多少，都可以正确地计算并返回newValue。
下面是修改后的doConversion方法的代码：
public double doConversion(double originalValue, char originalScale, char newScale) {
double newValue = 0.0;
if (originalScale == CELSIUS || originalScale == 'c') {
newValue = celsiusToOther(originalValue, newScale);
} else if (originalScale == KELVIN || originalScale == 'k') {
newValue = kelvinToOther(originalValue, newScale);
} else if (originalScale == FAHRENHEIT || originalScale == 'f') {
newValue = fahrenheitToOther(originalValue, newScale);
} else if (originalScale == ANKINE || originalScale == 'r') {
newValue = rankineToOther(originalValue, newScale);
}
return newValue;
}
希望这可以解决你的问题！如果还有任何疑问，请随时提问。
【以下回答由 GPT 生成】
问题出在方法fahrenheitToOther的逻辑上，当scale为FAHRENHEIT或者'f'的时候，没有对newValue进行赋值，导致返回值始终为0.0。同时，也没有在每个分支中加入返回值的语句。
以下是修复后的代码：
import java.util.Scanner;
import java.io.*;
/**
* TemperatureConversion provides static methods that allow temperatures to be
* converted between 4 scales: celsius, fahrenheit, kelvin, rankine.
* Name: Xiangcheng Ding
* UniqueID: DINGX11
* Instructor: Dr. Deepak Dawar
* Course number and section: CSE271 Lab1
*
* @autho Jill Courte
* @modified Laurie Werner
* @version 1.1
*/
public class TemperatureConversion{
public final static char FAHRENHEIT = 'F';
public final static char CELSIUS = 'C';
public final static char KELVIN = 'K';
public final static char RANKINE = 'R';
/**
* Given a double value in fahrenheit and a scale, converts the value to that scale.
* @param value - the fahrenheit value to be converted
* @param scale - the target scale - one of 'F', 'C', 'K', 'R'
* @return the converted value
*/
public double fahrenheitToOther (double value, char scale) {
double newValue = 0;
if(scale==FAHRENHEIT || scale=='f'){
newValue = value;
}else if(scale==CELSIUS || scale == 'c'){
newValue=(value-32)/1.8;
} else if (scale == KELVIN || scale == 'k') {
newValue=(value-32)/1.8+273.15;
} else if (scale == RANKINE || scale == 'r') {
newValue=value+459.67;
}else {
return 0.0;
}
return newValue;
}
}
修复后的代码在每个分支中给newValue赋值，并且在方法的结束处返回newValue的值。
如果你已经解决了该问题, 非常希望你能够分享一下解决方案, 写成博客, 将相关链接放在评论区, 以帮助更多的人 ^-^