[Java] String comparison and && and ||

String comparison


number == 0

Suppose you have code like the one above. The meaning is that 0 is assigned to the variable number, which is equal to 0 on the right.

Then, in the case of letters ...? : thinking:


fruit == "Apple"

Isn't it? ?? : thinking: I think. In fact, it's a mistake. In Java, strings are supposed to be incomparable with ==. So what to do ...

String comparison.

String type variable.equals(String of comparison partner)

Will be: smile: So the previous code is



Will be: smile:

As an aside, using == in a string doesn't cause a compile error: sweat_smile: There is a bad problem that it can be executed but the movement is strange: sweat_smile: It's awkward to find an error just because it doesn't cause a compile error: sweat_smile:


: sunny: && is used when you want to match all two or more conditions such as "female and born in Tokyo". :sunny: ||Is used when you want to match something that meets any of the conditions, such as "female or born in Tokyo".

(Example) Over 20 years old and born in May


age >= 20 && month == 5

True if you are over 20 years old and born in May and all the conditions are met, otherwise false.

(Example) Over 20 years old or born in May


age >= 20 || month == 5

False if you are 20 years old or older or born in May and none of the above apply, otherwise true.

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