更新对象中的字段值

Question

I need to update a fields value inside one of my object, just update the String. The object is inside of an array. But I will target the object by typing in the objects "regNum" in the parameter.

This is what I tried, I really don't know how to use the set() method when I need to enter the list and the objects specific value.

public boolean doesNotWork( String regNumInput ){
    for(int i = 0; i < meterList.size(); i++){
        if(regNumInput == meterList.get(i).getRegNum()){
            meterList.set(meterList.get(i).getWorkOrNot(), new String ("No"));
        }
    }
    return true;
}

This Is the whole MeterArchive class that stores the meters and have some methods to it.

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class MeterArchive
{
// instance variables - replace the example below with your own
ArrayList<Meter> meterList = new ArrayList<Meter>();

public void createClocks(){
    Clock clockOne = new Clock("KH001", "Yes", "ClassRoom005", 0.0);
    meterList.add(clockOne);
    Clock clockTwo = new Clock("KH002", "Yes", "ClassRoom006", 0.0);
    meterList.add(clockTwo);
}

public boolean doesNotWork( String regNumInput ){
    for(int i = 0; i < meterList.size(); i++){
        if(regNumInput == meterList.get(i).getRegNum()){
            meterList.set(meterList.get(i).getWorkOrNot(), new String ("No"));
        }
    }
    return true;
}

public void showAllMeter(){
    for(Meter meter : meterList){
        System.out.println(meter);
    }
}
}

This is the clock class that has specific clock values that you can add.

public class Clock extends Meter
{

/**
 * Constructor for objects of class Clock
 */
public Clock(String regNum, String workOrNot, String location, double minTime)
{
    // initialise instance variables
    super(regNum, workOrNot, location);
    setMinTime(minTime);

}

//MINNIMUM TIME
public void setMinTime(double minTime){
    this.minTime = minTime;
}

public double getMinTime(){
    return minTime;
}

//EQUALS METHOD --- NOT SURE WHAT IT SHOULD DO... YET!
public boolean equals (Clock other){
    return location.equals(other.location);
}

public String toString(){
    String retur = super.toString() + "regNum: " + regNum +
                                      "Does it work: " + workOrNot +
                                      "Location: " + location +
                                      "Min time value: " + minTime;
    return retur;
}
}

This is the super class that has more general input for the different meters.

public class Meter
{

public String regNum;
public String workOrNot;
public String location;


/**
 * Constructor for objects of class Clock
 */
public Meter(String regNum, String workOrNot, String location)
{
    // initialise instance variables
    setRegNum(regNum);
    setWorkOrNot(workOrNot);
    setLocation(location);
}

//REGISTRATION NUMBER
public void setRegNum(String regNum){
    this.regNum = regNum;
}

public String getRegNum(){
    return regNum;
}

//WORK OR NOT
public void setWorkOrNot(String workOrNot){
    this.workOrNot = workOrNot;
}

public String getWorkOrNot(){
    return workOrNot;
}

//LOCATION
public void setLocation(String location){
    this.location = location;
}

public String getLocation(){
    return location;
}
}

So in the MeterArchive class I want to change the field value "workOrNot" from whatever it is (most likely "Yes") to "No". I found out that set() is usually the way to go, but in this program I want the user to add the specific "regNum" and then the method will change to String inside the "workOrNot" field to "No". As I said earlier I dont know how to target the specific field inside the object. Can someone explain how to do this?

Answer 1

You need to use setter method setWorkOrNot() to update field workOrNot on the desired Meter object.

Use the below code:

public boolean doesNotWork( String regNumInput ){
    for(int i = 0; i < meterList.size(); i++){
        if(regNumInput.equals(meterList.get(i).getRegNum())){
            meterList.get(i).setWorkOrNot("No");
        }
    }
    return true;
}