Question

我正在尝试运行以下程序，但遇到一些错误。有人可以帮助我，理解条件陈述的错误吗？

import java.util.Scanner;


public class separatingFirstCharacters {

    public static void main(String[] args) {
    Scanner reader = new Scanner(System.in);

        System.out.println("Type your name: ");
        String name = reader.nextLine();


        If (name.length()>3) {
            char firstcharacter =name.charAt(0);
            System.out.println ("First character : " + firstcharacter );
            char secondcharacter = name.charAt(1);
            System.out.println ("Second character : " + secondcharacter );
            char thirdcharacter=name.charAt(3);
            System.out.println("Third character: "+thirdcharacter);
            }
            else
            {
                System.out.println("name : " + name);
            }
        }       
    }

控制台错误：

Exception in thread "main" java.lang.Error: Unresolved compilation problems: 
    The method If(boolean) is undefined for the type separatingFirstCharacters
    Syntax error, insert ";" to complete Statement
    Syntax error on token "else", delete this token

    at separatingFirstCharacters.main(separatingFirstCharacters.java:13)

Answer 1

Java是区分大小写的语言，if是小写的。

Answer 2

你有1个编译问题（'if'应该是'if'）而另一个问题是第三个char是第四个（name.charAt（3）应该是name.charAt（2））：

import java.util.Scanner;

public class separatingFirstCharacters {

    public static void main(String[] args) {
        Scanner reader = new Scanner(System.in);

        System.out.println("Type your name: ");
        String name = reader.nextLine();

        if (name.length() > 3) {
            char firstcharacter = name.charAt(0);
            System.out.println("First character : " + firstcharacter);
            char secondcharacter = name.charAt(1);
            System.out.println("Second character : " + secondcharacter);
            char thirdcharacter = name.charAt(2);
            System.out.println("Third character: " + thirdcharacter);
        } else {
            System.out.println("name : " + name);
        }
    }
}

Answer 3

所有java基本语法都区分大小写，小写

如果（name.length（）→3）

Answer 4

排队如果（name.length（）＆gt; 3）{

改为 if（name.length（）＆gt; 3）{

请注意，如果应该用小写字母写

Answer 5

请纠正他的语法... 它应该是：

if (name.length()>3) {
     char firstcharacter =name.charAt(0);
     System.out.println ("First character : " + firstcharacter );
     char secondcharacter = name.charAt(1);
     System.out.println ("Second character : " + secondcharacter );
     char thirdcharacter=name.charAt(3);
     System.out.println("Third character: "+thirdcharacter);
    }
     else
       {
         System.out.println("name : " + name);
        }
     }

Java if-else条件语法错误？

5 个答案: