Java &&错误“未为参数类型java.lang.String，java.lang.String定义运算符&&”

Question

 if(pro_name.getText() && pro_price.getText() && pro_count.getText())
 {
 }

Am getting an error in eclipse java

The operator && is undefined for the argument type(s) java.lang.String, java.lang.String

Answer 1

&& operator is valid for checking boolean values

if(pro_name.getText()=="abc" && pro_price.getText().isEmpty() && pro_count.getText().equals("mango")){   }

above one is sample one...this wont produce compilation errors.

isEmpty() , equals() , equalsIgnoreCase() , contains() ==> these are the permissible operations on strings, each of them returns boolean values( true or false )

== this checks for equality and hence returns boolean true or false value

Answer 2

if (!pro_name.getText().isEmpty()
    && !pro_price.getText().isEmpty()
    && !pro_count.getText().isEmpty())

Conditions strictly require a boolean expression in java.

Answer 3

here getText() returns String , and in java && operator is only defined for boolean not for String .

This is why eclipse is showing this error.

Answer 4

You can only use && (AND) operator for booleans. .getText() returns a string, which is not a boolean values. You need to do a checkup that returns a boolean to do this, for example:

if(!pro_name.getText().isEmpty() ...)

Ie, if the answer from getText() is not null it will be translated to true. and tjhe && comparison will work.

A tip is to set a variable to the answer from getText() so you can reuse it, instead of later (I am asuming) you get the text again. Ie:

var pro_name_result = pro_name.getText();
if(!pro_name_result.isEmpty() ...) {