求大神帮帮~我想把stringbuffer转为String为什么这样不能写

Question

package work;
import java.util.*;

public class youxiang {
public static void main(String[]args){
Scanner input=new Scanner(System.in);
System.out.println("请输入一个字符串");
String s=input.next();
StringBuffer SB=new StringBuffer(s);
System.out.println(SB.reverse());
String str=SB.toString(SB.reverse());
if(s==str){
System.out.println("该字符串是回文");
}
}
}

Answer 1

根据你的代码推断你的意图和需求应该这样写   
 package work;
    import java.util.*;

    public class youxiang {
    public static void main(String[]args){
    Scanner input=new Scanner(System.in);
    System.out.println("请输入一个字符串");
    String s=input.next();
    StringBuffer SB=new StringBuffer(s);
    System.out.println(SB.reverse());
    String str=SB.toString(SB.reverse());
    if(s.equals(str)){
    System.out.println("该字符串是回文");
    }
    }
    }