我从来没有遇到过这个问题，因为没有给出任何错误，我不确定在哪里看。我对这个程序有点兴奋（这是我第一次做方法）。在此问题之前，它一直在抛出异常。当我研究那件作品并设法修复错误时，我感觉这是不对的。请告诉我整个代码是否已关闭（最好是一些建设性的批评）或者我是否接近：
import java.io.*;
public class InsuranceMethod2//class name here, same as file name
{
// use BufferedReader class to input from the keyboard
// declare a variable of type BufferedReader
private BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
//declare variable for input
private String inputString;
String carChoice;
boolean insurable;
int year;
public void InsuranceMethod2()throws IOException{//constructor, place class name here
String carChoice;
boolean insurable;
int year;
initialize();
insureProcess();
cleanUp();
}//end constructor
public void initialize(){
System.out.println();
System.out.println("Insurance Process Intializing");
}//end initialize
public void insureProcess() throws IOException {
String carChoice;
boolean insurable;
int year;
System.out.println("Enter your vehicle model: ");
inputString = input.readLine();
carChoice = inputString;
if(carChoice.equalsIgnoreCase("ford") || carChoice.equalsIgnoreCase("chevy") || carChoice.equalsIgnoreCase("toyota"))
{
System.out.println("Enter the vehicle year: ");
inputString = input.readLine();
year = Integer.parseInt(inputString);
if(year >= 1990)
{
System.out.println("Your vehicle is insurable");
}
}
}
public boolean checkModel(){
if(carChoice.equalsIgnoreCase("Ford")|| carChoice.equalsIgnoreCase("Chevy")|| carChoice.equalsIgnoreCase("Toyota"))
{
return true;
}
else
{
return false;
}
}//end checkModel
public boolean checkYear(int year){
return false;
}//end checkYear
public void printResults(boolean insurable){
}//end printResults
public void cleanUp(){
System.out.println("Program ending");
}//end cleanUp
public static void main(String [] args) throws IOException // main method
{
new InsuranceMethod2(); //class constructor name
} // end the main method
} // end the program
答案 0 :(得分：3)
public void InsuranceMethod2() throws IOException{ //constructor
那不是构造函数。这只是一种方法（名称非常混乱）。
你想要
public InsuranceMethod2() throws IOException{ //constructor
如果没有它，你只需得到一个什么都不做的默认构造函数。
您还应该将所有从构造函数调用的方法设置为private或至少是final。
答案 1 :(得分：1)
您的程序唯一能做的就是创建InsuranceMethod类的新实例。然后运行此类的构造函数，并且由于您尚未定义一个（您定义的方法具有使其不是构造函数的返回类型），因此默认构造函数运行（并且不执行任何操作）。因此，您没有看到任何输出。如果您希望以相同的名称调用该方法，请写：
new InsuranceMethod2().InsuranceMethod2();
否则，您应该从方法中删除void关键字，将其转换为构造函数。
答案 2 :(得分：1)
public void InsuranceMethod2()throws IOException{//constructor, place class name here
上面的代码不是构造函数，因为它是方法声明。如果您希望它是构造函数，请删除void，因此它看起来像这样：
public InsuranceMethod2() throws IOException{ ... }
此外，您已经全局声明了变量，不需要在每个方法中再次声明它们，因为当您尝试引用该变量时，它将引用本地声明的变量而不是全局声明的变量，因此您会收到意想不到的结果
作为提示，如果您的全局变量声明和局部变量声明中有通用的字段名称，则可以通过在其前面添加this.后缀来引用全局变量。
答案 3 :(得分：0)
您的代码中似乎存在一些误解。要回答直接问题，构造函数没有返回类型（请参阅this tutorial）。因此，只需将构造函数（在您的情况下实际上是一个方法）更改为
public InsuranceMethod2() throws IOException{ ... }
为了解决其他误解（在哪里声明变量，样式等），我用注释重写了你的代码（寻找LEBOLO）。有关样式的详细信息，最好只使用Google“java代码样式”或“java代码约定”。我希望这有助于您指出更多的学习资源！玩得开心！
import java.io.*;
public class InsuranceMethod2 { //class name here, same as file name
// use BufferedReader class to input from the keyboard
// declare a variable of type BufferedReader
private BufferedReader input = new BufferedReader( new InputStreamReader(System.in) );
// declare variable for input
//private String inputString; // LEBOLO: Remove, don't need (see larger comment below for details)
/* LEBOLO
*
* Do you want all of these as class level variables? I assume you don't since you don't use them all.
* In general, you only put variables here (called instance variables) if you want multiple methods to share them.
* You don't have to declare variables here just because one method uses them.
* See http://docs.oracle.com/javase/tutorial/java/javaOO/variables.html for details.
*
* Also, by not stating a modifier (e.g. private or public), Java defaults to the package access level.
* See http://docs.oracle.com/javase/tutorial/java/javaOO/accesscontrol.html for details
*/
String carChoice; // LEBOLO: I think you want this private
//boolean insurable; // LEBOLO: Remove, don't need
//int year; // LEBOLO: Remove, don't need
// LEBOLO: Removed the void return type.
// See http://docs.oracle.com/javase/tutorial/java/javaOO/constructors.html for details.
public InsuranceMethod2() throws IOException { // constructor, place class name here
//String carChoice; // LEBOLO: Remove, don't need
//boolean insurable; // LEBOLO: Remove, don't need
//int year; // LEBOLO: Remove, don't need
initialize();
insureProcess();
cleanUp();
} // end constructor
public void initialize() {
System.out.println();
System.out.println("Insurance Process Intializing");
} // end initialize
public void insureProcess() throws IOException {
/* LEBOLO
*
* Since you use the 'year' variables here, it makes sense to declare it here (local variables).
* You don't use 'insurable' and 'carChoice' is an instance (class level) variable, so no need to declare here.
*/
//String carChoice; // LEBOLO: Remove, don't need (since using the instance variable)
//boolean insurable; // LEBOLO: Remove, don't need
int year;
System.out.println("Enter your vehicle model: ");
// LEBOLO: Declare inputString here, since you only use it here
String inputString = input.readLine();
carChoice = inputString;
if (carChoice.equalsIgnoreCase("ford") || carChoice.equalsIgnoreCase("chevy") || carChoice.equalsIgnoreCase("toyota")) {
System.out.println("Enter the vehicle year: ");
inputString = input.readLine();
year = Integer.parseInt(inputString);
if (year >= 1990) {
System.out.println("Your vehicle is insurable");
}
}
}
public boolean checkModel() {
if(carChoice.equalsIgnoreCase("Ford")|| carChoice.equalsIgnoreCase("Chevy")|| carChoice.equalsIgnoreCase("Toyota")) {
return true;
}
else
{
return false;
}
/* LEBOLO: A cleverer way would be
*
* return (carChoice.equalsIgnoreCase("Ford")|| carChoice.equalsIgnoreCase("Chevy")|| carChoice.equalsIgnoreCase("Toyota"));
*/
}//end checkModel
/* LEBOLO
*
* If you want to use the shared year, then declare the variable at the class level (instance variable)
* and remove it from the method signature (instead using it within the method body).
*
* public boolean checkYear() {
* return (year >= 1990);
* } // end checkYear
*
* If you want the user to say checkYear(1993), then leave this as is.
*/
public boolean checkYear(int year) {
return false;
} // end checkYear
/* LEBOLO
*
* See my comment for checkYear(...)
*/
public void printResults(boolean insurable) {
} // end printResults
public void cleanUp() {
System.out.println("Program ending");
} // end cleanUp
public static void main(String [] args) throws IOException { // main method
new InsuranceMethod2(); // class constructor name
} // end the main method
} // end the program