试图检索包含空格的字符串的最后一个字母

Question

对，所以我有点卡住试图检索使用.substring的最后一个字母。如果我输入例如“100C”，它将正常工作，变量celOrFar将=“C”。但是，用户应该在数字后插入一个空格，但这样做会给我一个不正确的结果。 “100 C”会给我“0”而不是C，“1234 5678C”会给我4！我仍然是Java的初学者，所以任何帮助表示赞赏！

public static void stateOfWater() {  

    System.out.println("Enter a temperature followed by a space and C/F: "); 
    String userInput = input.next(); 
    String celOrFar = userInput.substring(userInput.length()-1); 

    String degreeString = userInput.trim(); 
    degreeString = degreeString.replace("C", ""); 
    degreeString = degreeString.replace("F", ""); 
    degreeString = degreeString.replace("f", ""); 
    degreeString = degreeString.replace("c", ""); 

    int degree = Integer.parseInt(degreeString);  

    if (celOrFar.equals("C")|| celOrFar.equals("c")) {   
     if (degree <= 0) {System.out.println("Your water is a solid at " +userInput);}   
     if (degree >= 100) {System.out.println("Your water is a gas at " +userInput);}  
     if (degree >0 && degree <100) {System.out.println("Your water is a liquid at " +userInput);}    
    } 

    if (celOrFar.equals("F") || celOrFar.equals("f")) {   
     if (degree <= 32) {System.out.println("Your water is a solid at " +userInput);}   
     if (degree >= 212) {System.out.println("Your water is a gas at " +userInput);}   
     if (degree >32 && degree <212) {System.out.println("Your water is a liquid at " +userInput);}   
    } 
} 

Answer 1

scanner.next读字符，直到它遇到一个空格。如果你想阅读包括空格在内的完整行，那么你需要使用nextLine。见下文。

public static void stateOfWater() {  

System.out.println("Enter a temperature followed by a space and C/F: "); 
String userInput = input.nextLine(); // this will read the complete line including spaces. 
String celOrFar = userInput.substring(userInput.length()-1); 

String degreeString = userInput.trim(); 
degreeString = degreeString.replace("C", ""); 
degreeString = degreeString.replace("F", ""); 
degreeString = degreeString.replace("f", ""); 
degreeString = degreeString.replace("c", ""); 

int degree = Integer.parseInt(degreeString);  

if (celOrFar.equals("C")|| celOrFar.equals("c")) {   
    if (degree <= 0) {System.out.println("Your water is a solid at " +userInput);}   
    if (degree >= 100) {System.out.println("Your water is a gas at " +userInput);}  
    if (degree >0 && degree <100) {System.out.println("Your water is a liquid at " +userInput);}    
} 

if (celOrFar.equals("F") || celOrFar.equals("f")) {   
    if (degree <= 32) {System.out.println("Your water is a solid at " +userInput);}   
    if (degree >= 212) {System.out.println("Your water is a gas at " +userInput);}   
    if (degree >32 && degree <212) {System.out.println("Your water is a liquid at " +userInput);}   
    } 
}