如何将这段代码放入循环中，以便每次都要求用户输入，直到结果为“kill”？

Question

I was practicing this piece of code from the book 'Head First Java' and I'm quite confused on the positioning of the loop here.The code is for creating a kind of game that has a random dotcom word(ex: abc.com) occupying some array elements. here I gave that dotcom word the positions from 3 to 5 in the array, and the user tries guessing the position.

import java.util.Scanner;

public class RunTheGame {

    public static void main(String[] args) {

        MainGameClass sampleObj= new MainGameClass();
        int[] location = {3,4,5};
        sampleObj.setdotcomLocationCells(location);


        Scanner input= new Scanner(System.in);
        System.out.println("Enter your guess");
        int userGuess=input.nextInt();

        String answer = sampleObj.checkForDotcom(userGuess);
        System.out.println(answer);

    }
}

---

package simpleDotComGame;

public class MainGameClass {
    int[] DotcomLocationCells;
    int numOfHits=0;

    public void setdotcomLocationCells(int[] location) {
        DotcomLocationCells= location;
    }

    public String checkForDotcom(int userGuess) {
        String result="miss";
        for(int cell:DotcomLocationCells) {
            if(cell == userGuess) {
                result ="hit";
                numOfHits++;
                break;
            }
        } // end for loop

        if(numOfHits == DotcomLocationCells.length) {
            result = "kill";            
            System.out.println("The number of tries= "+numOfHits);
        }
}

Answer 1

do {
        <insert code where answer result is created>
} while (!answer.equals("kill"))

upd.: but you must override the equals method for correct use, because if you see how method declared in Object.class you find

public boolean equals(Object obj) {
    return (this == obj);

Answer 2

Rachna, the loop will be positioned, around the following code:

Scanner input= new Scanner(System.in);
System.out.println("Enter your guess");
int userGuess=input.nextInt();

String answer=sampleObj.checkForDotcom(userGuess);
System.out.println(answer);
//For string you must use the equals
if ("kill".equals(answer)){
   break;
}

The reason why is that the kill command must be evaluated inside the loop to break it, and the input to continuously ask the user input until he hits all targets.

Answer 3

Here's how the loop should be positioned.

String answer = "";
do{
    System.out.println("Enter your guess");
    int userGuess=input.nextInt();

    answer=sampleObj.checkForDotcom(userGuess);
    System.out.println(answer);
}
while(!answer.equals("kill"));  

NOTE : Never Check for String equality using == in Java unless you know what you're doing (also read as, unless you know the concept of String Constant Pool).

Answer 4

You are allowed to declare the variable before initializing it:

String answer;
do {
  answer = sampleObj.checkForDotcom(userGuess);
  System.out.println(answer);
} while (!answer.equals("kill");

Also beware of the semantics of Scanner.nextInt() : if it can't parse the input as an int (for example, it contains letters), it will throw an exception, but won't jump over the invalid input. You'll have to use Scanner.nextLine() to force-jump over it, otherwise you'll get an infinite loop.