Why does a string read from a txt file using java scanner not equal an identical string?

Question

Below is my code, goal is to read instructions from a txt file to make java robot preform them. When changing any part of the if statement to != the robot portion works, therefore I have to think that the strings are in some way not equal.

public void interpretGoo() throws AWTException, FileNotFoundException, 
InterruptedException{
    Scanner scanner = new Scanner( new File("instruct.txt") );
    String in;
    String instruct = "";
    while(scanner.hasNextLine()== true){
        in = scanner.nextLine();
        instruct+= in;
    }
    scanner.close();

    String[] instructSet= instruct.split("-");
    System.out.println("String: " + instruct);

    String[] command= new String[10];
    for(int i= 0; i< instructSet.length;i++){
        command= instructSet[i].split(" ");
        System.out.println("Set: " + instructSet[i]);
        System.out.println("Word: " + command[0]);
        if(command[0].trim()== "key"){
            keyboardHandler(command[1].charAt(1));
            Thread.sleep(150);
        }else if(command[0].trim()== "clickL"){
            accuMouse(Integer.parseInt(command[1]),Integer.parseInt(command[2]), 1, false);
        }else if(command[0].trim()== "clickR"){
            accuMouse(Integer.parseInt(command[1]),Integer.parseInt(command[2]), 0, true);
        }else{
            System.out.println("FAIL");
            continue;
        }
    }
}

OUTPUT:

String: clickL 728 1062-clickL 540 382-key h-key e-key l-key l-key o-
Set: clickL 728 1062
Word: clickL
FAIL
Set: clickL 540 382
Word: clickL
FAIL
Set: key h
Word: key
FAIL
Set: key e
Word: key
FAIL
Set: key l
Word: key
FAIL
Set: key l
Word: key
FAIL
Set: key o
Word: key
FAIL

According to the output the strings are identical but fail the checks, any help would be appreciated!

Only the contents of the strings are identical. But not the objects themselves. `==` compares for **identity**, not for *content*. Use `equals` to compare for *content*. Also note that comparisons against `true` or `false` are obsolete: `while (foo == true)` is the same as `while (foo)`. — Zabuzard, Jul 16 '18 at 18:24

score 1 · Accepted Answer · answered Jul 16 '18 at 18:21

1

You need to use .equals for string comparison in Java. You’ll find many identical strings do not equal one another if you just use ==. The same goes for most objects. In general it’s safer to use .equals() for equality in Java.

answered Jul 16 '18 at 18:21

K. Dackow

456
1
3
15

That seems counter intuitive to me but it worked. The hardest question is the one you didn't know you didn't know. Thank you! – Hopelessdecoy Jul 16 '18 at 18:34
Check this out for clarification: https://stackoverflow.com/questions/7520432/what-is-the-difference-between-vs-equals-in-java – K. Dackow Jul 16 '18 at 18:49

Why does a string read from a txt file using java scanner not equal an identical string?

1 Answers1