java - BlueJ 字符串条件错误

Question

我的 BlueJ 在条件语句 if 中运行了错误的行。我的程序是:

import java.io.*;
public class version_check
{
    public static void main(String args[])throws IOException
    {
        BufferedReader read=new BufferedReader(new InputStreamReader(System.in));
        System.out.println("Enter your BlueJ version");
        String version=read.readLine();
        if(version!="3.1.1")
        System.out.println("You need to upgrade your BlueJ version");
        else
        System.out.println("You have the latest BlueJ version");
    }
}

输出屏幕:

Enter your BlueJ version
3.1.1
You need to upgrade your BlueJ version

我犯了什么错误？

Answer 1

使用 .equals 比较字符串。

if(version!="3.1.1")   
        System.out.println("You need to upgrade your BlueJ version");  

到

if(!(version.equals("3.1.1")))   
        System.out.println("You need to upgrade your BlueJ version");