检查输入的字符串长度是否等于三

Question

I need to create a code that checks if the input from the user is equal to a double literal length 3. my if statement is where i am having trouble. Thanks

Scanner stdIn= new Scanner(System.in);
String one;
String two;
String three;

System.out.println("Enter a three character double literal ");
one = stdIn.nextLine();

if (!one.length().equals() "3")
{
  System.out.println(one + " is not a valid three character double literal");
}

Answer 1

Comparison

if (one.length() != 3)

instead of

if (!one.length().equals() "3")

Answer 2

if (one.length() != 3)

if (!(one.length().equals(3))

Both these ways work.

For more details please refer this.

https://www.leepoint.net/data/expressions/22compareobjects.html

Answer 3

if (!(one.length().equals(3)) {
    System.out.println(one + " is not a valid three character double literal");
}

You have to place the 3 as an argument to the equals function ( it takes an argument).

More common is to use == when comparing numbers though.

if (!(one.length() == 3) {
    System.out.println(one + " is not a valid three character double literal");
}

or more concise:

if (one.length() != 3) {
    System.out.println(one + " is not a valid three character double literal");
}

Answer 4

您不需要使用.equals（），因为length方法返回一个int值。

if ( one.length() != 3 ) { do something; }