error: unreachable statement

Frage zur Aufgabe

In der Diskussion

Hi guys, apparently I get this error message after the first while loop for whatever I do and I dont quite understand why. Any ideas? Thanks in advance!

Schreib ein Programm, das:
1. liest eine Zahl N (muss größer sein als 0) von der Konsole ein
2. liest N Zahlen von der Konsole ein
3. Zeigt die größte der N eingegebenen Zahlen an.

Anforderungen:

Das Programm muss die Zahlen von der Tastatur einlesen.
Das Programm muss eine Zahl auf dem Bildschirm anzeigen.
Die Klasse muss die Methode public static void main besitzen.
Füge der Klasse Solution keine neuen Methoden hinzu.
Das Programm muss die größte der N eingegebenen Zahlen anzeigen.
Das Programm darf nichts anzeigen, wenn N kleiner oder gleich 0 ist.

package de.codegym.task.task05.task0532; import java.io.*; /* Aufgabe zu Algorithmen */ public class Solution { public static void main(String[] args) throws Exception { BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); int maximum = 0; int zaehler = 0; int i = 0; //schreib hier deinen Code while(true){ int z = Integer.parseInt(reader.readLine()); i++; } System.out.println(i); /*while(zaehler < i){ int zahl = Integer.parseInt(reader.readLine()); if(zahl <= 0){ break; } if(maximum < zahl){ maximum = zahl; } zaehler++; } if(maximum > 0){ System.out.println(maximum); }*/ } }

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Thomas

Level 41 , Bayreuth, Germany

10 Juni 2020, 14:26

nützlich

You have an infinite loop with no break condition. So everything after the loop never can be reached. If you add eg.

if (false) break;

it is still an infinite loop but has a break condition (that never can be reached). Nevertheless the compiler is happy with this.

sidelkid

Level 8 , Gottingen, Germany

10 Juni 2020, 17:59

That makes perfect sense, however I am struggling to implement the "break" correctly. My try goes like this: while(true){ int z = Integer.parseInt(reader.readLine()); if(z <= 0){ break; } i++; } System.out.println(i); Where did i go wrong?

Thomas

Level 41 , Bayreuth, Germany

10 Juni 2020, 19:20

You'd need a counter variable that you increment each time a number has been read. If that counter reaches N you stop the loop. That's the classic use case for a for loop

for (int i = 0; i < N; i++) {

int counter = 0;
while (counter < N) {
counter++;
//do something...

or with an infinite loop

int counter = 0;
while (true) {
counter++;
if (counter == N) break;
//do something...
}

sidelkid

Level 8 , Gottingen, Germany

10 Juni 2020, 19:23

The problem Im facing is that I want the program to count how big N is. Thats what Im trying to accomplish with the while loop. I dont see how a for loop would help me here.

Thomas

Level 41 , Bayreuth, Germany

10 Juni 2020, 19:28

You need to read N numbers... First you read N Define a variable int max and set it to Integer.MIN_VALUE (that's a constant holding the smallest number possible for integers) then the loop over N iterations inside the loop you read numbers, each iteration of course one number as asked in the requirements. Compare the number to max, if max is bigger, set max to number finally output the result

Thomas

Level 41 , Bayreuth, Germany

10 Juni 2020, 19:31

If you don't want to use the constant, check in the loop if it is the first iteration ( i == 0) and initialize max with number.