Returning a set of array to the main method using for loop, gives error deadcode

Currently programming a Clock with an alarm and met my first Dead Code error.

User input have already stored data into the following variables; aAlarm, aHour, and aMinute.. but I can't seem to get them to display into the main method. I have tried searching other problems regarding dead error and none seem to solve my problem. Below is the code, the variable 'instances' equals to 1 and will increment for the amount of times the user creates an alarm.

import java.util.*;
public class Frontend {
public static void main(String args[]) {
Backend nyet = new Backend();
Scanner scn = new Scanner(System.in);
int dec, dec2;
System.out.print("The time is: ");
System.out.println(nyet.displayClock());
//Class clock----------------------------
//Class setTime--------------------------
System.out.print("Do you wish to alter time| 1 = Yes, 0 = No:");
dec = scn.nextInt();
if (dec == 1) {
System.out.print("Input Hour:");
int hour = scn.nextInt();
if (hour < 0 || hour > 24) {
System.out.println("Sorry, there are only 24hrs in one day.");
System.exit(0);
}
System.out.print("Input Minute:");
int minute = scn.nextInt();
if (minute < 0 || minute > 60) {
System.out.println("Sorry, there are only 60mins in one hour.");
System.exit(0);
}
System.out.print("Input Second:");
int second = scn.nextInt();
if (second < 0 || second > 60) {
System.out.println("Sorry, there are only 60second in one minute.");
System.exit(0);
}
nyet.setTime(hour, minute, second);	
scn.close();
System.out.print("The time is: ");
System.out.println(nyet.displayClock());
}				//Class setTime--------------------------
//Class setAlarm-------------------------
System.out.print("Do you wish to set an alarm| 1 = Yes, 0 = No:");
int dec1 = scn.nextInt();
if (dec1 == 1) {
do {
int instc = 1;
System.out.print("Input alarm number:");
int aNum = scn.nextInt();
System.out.print("Input Hour:");
int aHr = scn.nextInt();
if (aHr < 0 || aHr > 24) {
System.out.println("Sorry, there are only 24hr in one day.");
System.exit(0);
}
System.out.print("Input Minute:");
int aMin = scn.nextInt();
if (aMin < 0 || aMin > 60) {
System.out.println("Sorry, there are only 60mins in one hour.");
System.exit(0);
}
System.out.print("Do you wish to set another alarm| 1 = Yes, 0 = No:");
dec2 = scn.nextInt();
if (dec2 == 1)
instc++;
nyet.setAlarm(instc, aNum, aHr, aMin);
}while (dec2 != 0);
}				//Class setAlarm-------------------------
System.out.print("Show alarm| 1 = Show, 0 = Nothing:");
int z = scn.nextInt();
if (z == 1)
nyet.displayAlarm();
}
}

import java.time.OffsetTime;
public class Backend {
OffsetTime nyet = OffsetTime.now();
private int cHour, cMinute, cSecond, instances;
private int[] aAlarm, aHour, aMinute;
private boolean[] alarmOn;
public Backend() {
cHour = nyet.getHour();
cMinute = nyet.getMinute();
cSecond = nyet.getSecond();
aHour = new int[2];
aMinute = new int[2];
aAlarm = new int[2];
alarmOn = new boolean[2];
for (int i = 0; i < 2; i++) {
alarmOn[i] = !alarmOn[i];
}
}
public void setAlarm(int instncs,int aNmbr, int aHr, int aMnt) {
for (int i = 0; i < instncs; i++) {
aAlarm[i] = aNmbr;
aHour[i] = aHr;
aMinute[i] = aMnt;
instances = instncs;
}
}
public void setTime(int hr, int min, int sec) {
cHour = hr;
cMinute = min;
cSecond = sec;
}
public String displayClock() {
return String.format("%02d:%02d:%02d", cHour, cMinute, cSecond);
}
public String displayAlarm() {
for (int i = 0; i < instances; i++) { //<<< Dead Code
return String.format("%02d:%02d:%02d", aAlarm[i], aHour[i], aMinute[i]);
}
}
}

When I entered the code for your class Backend in my Eclipse, it showed a build error for method displayAlarm(), namely...
> This method must return a result of type String

Here is the code for method displayAlarm() (exactly as it appears in your question).

public String displayAlarm() {
for (int i = 0; i < instances; i++) { //<<< Dead Code
return String.format("%02d:%02d:%02d", aAlarm[i], aHour[i], aMinute[i]);
}
}

It is possible that the for loop in the method will not be entered and in that case the method does not return anything. So I just added a line to get rid of the build error.

public String displayAlarm() {
for (int i = 0; i < instances; i++) { //<<< Dead Code
return String.format("%02d:%02d:%02d", aAlarm[i], aHour[i], aMinute[i]);
}
return "";
}

After adding the line, I got the dead code warning. I admit that it took me a while to discover the reason. Finally it dawned on me. The only thing in the for loop body is return. Hence there will only ever be precisely one loop iteration, so why increment i?

Guess the problem was the class had no 'static' in it.

Front end code:

public static void main(String args[]) {
int dec, dec2, amount = 0, deci0;
Backend nyet = new Backend();
Scanner scn = new Scanner(System.in);

System.out.print("Do you wish to set an alarm| 1 = Yes, 0 = No:");
int dec1 = scn.nextInt();
if (dec1 == 1) {
do {
System.out.print("Input alarm number(Stored = " + amount + "):");
int aNum = scn.nextInt();
System.out.print("Input Hour:");
int aHr = scn.nextInt();
if (aHr < 0 || aHr > 24) {
System.out.println("Sorry, there are only 24hr in one day.");
System.exit(0);
}
System.out.print("Input Minute:");
int aMin = scn.nextInt();
if (aMin < 0 || aMin > 60) {
System.out.println("Sorry, there are only 60mins in one hour.");
System.exit(0);
}
nyet.setAlarm(amount, aNum, aHr, aMin);
System.out.print("Do you wish to set another alarm(max 3)| 1 = Yes, 0 = No:");
dec2 = scn.nextInt();
if (dec2 == 1) {
amount++;
}else if (dec2 == 0) {
amount++;
nyet.setAlarm(amount, aNum, aHr, aMin);
}else {
System.out.println("The only choices are '1' and '0'.");
System.exit(0);
}
if (amount > 3) {
System.out.println("You have reached maximum storage.");
dec2 = 0;
}
}while (dec2 != 0);
}

Back end code:

public class Backend {
OffsetTime nyet = OffsetTime.now();
private int cHour, cMinute, cSecond;
private static int[] aAlarm, aHour, aMinute;
private boolean[] alarmOn;
private static int amnt;

public void setAlarm(int instncs,int aNmbr, int aHr, int aMnt) {
int i = instncs;
aAlarm[i] = aNmbr;
aHour[i] = aHr;
aMinute[i] = aMnt;
amnt = instncs;
}
public static void displayAlarm() {
for (int i = 0; i < amnt; i++) {
System.out.println("Alarm #" + aAlarm[i] + " - " + aHour[i] + ":" + aMinute[i]);
}
}