英文:
String is palindrome or not
问题
我需要检查一个字符串是否是回文，但我总是得到"not palindrome"。我的错误是什么？
public static void main(String[] args) {
String st = "iti";
StringBuffer st1 = new StringBuffer(st);
st1.reverse();
System.out.println(st1);
System.out.print(st.equals(st1));
if (st1.equals(st) == true) {
System.out.print("回文字符串");
} else {
System.out.print("不是回文");
}
}
英文:
I need to check whether a string is a palindrome, but I'm always getting "not palindrome". What's my mistake?
public static void main(String[] args) {
String st = "iti";
StringBuffer st1 =new StringBuffer(st);
st1.reverse();
System.out.println(st1);
System.out.print(st.equals(st1));
if(st1.equals(st)==true) {
System.out.print("palindrome string");
} else {
System.out.print("not palindrome");
}
}
答案1
得分: 2
A StringBuffer 不是一个 String，因此它永远不会等于一个 String。请与 st1.toString() 比较而不是与 st 比较。
另外，在 if(st1.equals(st)==true) 中，与 true 比较布尔值是不必要的，容易出错。你应该将其写成 if(st1.toString().equals(st))，这样你就不会因错误使用单个 = 并引入难以注意到的错误。
class Palindrome {
public static void main(String[] args) {
String st = "iti";
StringBuffer st1 = new StringBuffer(st);
st1.reverse();
if (st1.toString().equals(st)) { // 注意这里使用了 `toString`
System.out.print("回文字符串");
} else {
System.out.print("不是回文");
}
}
}
英文:
A StringBuffer is not a String, thus it will never be equal to a String. Compare st with st1.toString() instead.
As an aside, in if(st1.equals(st)==true) comparing a boolean with true is not necessary and error-prone. You should write it as if(st1.toString().equals(st)) so you don't use a single = by mistake and introduce a bug that can be rather hard to notice.
class Palindrome {
public static void main(String[] args) {
String st = "iti";
StringBuffer st1 =new StringBuffer(st);
st1.reverse();
if(st1.toString().equals(st)) { // HERE notice the use of `toString`
System.out.print("palindrome string");
} else {
System.out.print("not palindrome");
}
}
}
答案2
得分: 0
public static void main(String[] args) {
String st = "iti";
StringBuffer st1 = new StringBuffer(st);
st1.reverse();
System.out.println(st1);
System.out.println(st.equals(st1));
if (st.equals("" + st1)) { // convert st1 from StringBuffer to String
System.out.print("回文字符串");
} else {
System.out.print("不是回文字符串");
}
}
英文:
public static void main(String[] args) {
String st = "iti";
StringBuffer st1 =new StringBuffer(st);
st1.reverse();
System.out.println(st1);
System.out.println(st.equals(st1));
if(st.equals(""+st1)) { // convert st1 from StringBuffer to String
System.out.print("palindrome string");
} else {
System.out.print("not palindrome");
}
}
答案3
得分: 0
To derive the String value within StringBuffer, you need to call the toString method.
System.out.print(st.equals(st1.toString()));
And, at your if-conditional statement.
if(st1.toString().equals(st)==true)
英文:
To derive the String value within StringBuffer, you need to call the toString method.
System.out.print(st.equals(st1.toString()));
And, at your if-conditional statement.
if(st1.toString().equals(st)==true)
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