Checking if a String contains the letters I want plus a whitespace at the end of it

Question

Im looking for a way to check if the String the User enters, contains two things: First: It should start with "hello "(its hello and a whitspace!) or if it starts with a number. If both is false I want to print out false , if one of both is true i print out true.

if (text.startsWith("hello ") == false)
{
    if (Character.isDigit(text.CharAt(0)) == false)
    { 
        System.out.println("false"); 
    }

    Syso("true"); 
}
Syso("true");

I know that the two If's are not the smartest choice in this case but im fine with this. The only problem I have at the Moment is that if the text is "hello" so without a whitespace it still gives me true. Does it have to do something with the method startsWith? is there another method to use ?

Sorry , My english is bad and I'm knew to programming. But thanks for the feedbak

Answer 1

You want something to be true if one of two conditions is true. This is thus a logical or :

System.out.println(text.startsWith("hello ") || Character.isDigit(text.charAt(0)));

Answer 2

if (! text.startsWith ("hello ") && ! Character.isDigit (text.charAt (0)) {
          Syso ("false"); 
}
else Syso ("true"); 

This can be further condensend. If (! a && ! b) is equivalent to if (! (a || b)).

if (! (text.startsWith ("hello ") || Character.isDigit (text.charAt (0)))) {
          Syso ("false"); 
}
else Syso ("true"); 

Negating the condition is, however, confusing. So if there is no good reason, you should formulate a positive, hence more simple condition:

    if (text.startsWith ("hello ") || Character.isDigit (text.charAt (0))) 
              Syso ("true"); 
    else Syso ("false"); 

I can't reproduce your error with the blank - maybe you tricked yourself with the too-much-negation?

Note, that you should test your example code to reproduce your error - and cut and paste it, to prevent new errors. String.charAt (0) must start with a lower c in the method name.

Note, that you need an ' else ' after the closing braces, to reach your goal.

Answer 3

The way you included print statements in your code is wrong. The problem in your code is if it doesn't start with 'hello ' it enters the if block. If it doesn't start with a digit, it further enters the inner if, prints false. Once it comes out it prints true and then after outer if it prints a true again.

if (str.startsWith("hello ") || Character.isDigit(str.charAt(0))) {
    System.out.println("True");
}
else{
    System.out.println("False");
}

Answer 4

try using trim() method, trim takes off the white spaces from a text:

String txt = "hello ";
System.out.println(txt.trim() + jhon);

console: hellojhon