java -错误：<identifier>预期

Question

我试图通过这个网站学习java：input.html，但是当我在Ubuntu中通过终端运行代码时，我会得到以下错误：

vonvic@BSW-Computer:~/Java_Applications$ javac StringVariables2.java
StringVariables2.java:3: error: '{' expected
    public static class main(String[] args) {
                        ^
StringVariables2.java:8: error: <identifier> expected
        System.out.println("Please enter your first name")
                      ^
StringVariables2.java:8: error: illegal start of type
        System.out.println("Please enter your first name")
                           ^
StringVariables2.java:8: error: ';' expected
    System.out.println("Please enter your first name")
                                                      ^
StringVariables2.java:12: error: <identifier> expected
    System.out.println("Please enter your family name")
                      ^
StringVariables2.java:12: error: illegal start of type
    System.out.println("Please enter your family name")
                       ^
StringVariables2.java:12: error: ';' expected
    System.out.println("Please enter your family name")
                                                       ^
StringVariables2.java:16: error: <identifier> expected
    full_name = first_name +" "+ family_name;
             ^
StringVariables2.java:18: error: <identifier> expected
    System.out.println("You are" + full_name);
                      ^
StringVariables2.java:18: error: illegal start of type
    System.out.println("You are" + full_name);
                       ^
StringVariables2.java:18: error: ')' expected
        System.out.println("You are" + full_name);
                                ^
StringVariables2.java:18: error: ';' expected
            System.out.println("You are" + full_name);
                                  ^
StringVariables2.java:18: error: illegal start of type
        System.out.println("You are" + full_name);
                                            ^
StringVariables2.java:18: error: <identifier> expected
        System.out.println("You are" + full_name);
                                             ^
StringVariables2.java:18: error: ';' expected
        System.out.println("You are" + full_name);
                                              ^
StringVariables2.java:20: error: reached end of file while parsing
}
 ^
16 errors
vonvic@BSW-Computer:~/Java_Applications$ 

以下是代码：

import java.util.Scanner;

public class StringVariables2 {

    public static class main(String[] args) {

    Scanner user_input = new Scanner( System.in );

    String first_name;
    System.out.println("Please enter your first name")
    first_name = user_input.next();

        String first_name;
        System.out.println("Please enter your family name")
        first_name = user_input.next()

        String full_name;
        full_name = first_name +" "+ family_name;

        System.out.println("You are" + full_name);
    }
}

我用的是Ubuntu 13.10 Saucy Salamander。

现在我明白了：

vonvic@BSW-Computer:~/Java_Applications$ javac StringVariables2.java

StringVariables2.java:13: error: variable first_name is already defined in method     main(String[])
    String first_name;
           ^
StringVariables2.java:18: error: cannot find symbol
    full_name = first_name + " " + family_name;
                                   ^
  symbol:   variable family_name
  location: class StringVariables2
2 errors

Answer 1

看来你忘了在你的一些陈述的结尾加上分号了：

System.out.println("Please enter your first name");

System.out.println("Please enter your family name");
first_name = user_input.next();

编辑：

您的main也应该是一个方法(而不是一个类)

   public static void main(String[] args) 

Answer 2

您需要将main声明为方法，而不是类：

public static void main(String[] args)

将main声明为类在该类中的顶层放置了几个可执行语句，其中只允许声明。