How to Iterate through LinkedList that contains Object - Java

问题

How can i iterate through my LinkedList which i added Objects?

private LinkedList sensors = new LinkedList();
enter code here

//Constructor for my class is taking three arguments
public Sensor(int ID, String Name, String comments) {
    this.ID = ID;
    this.NAME = Name;       
    this.COMMENTS = comments;
}

//Then I query the database to get the values of the variables to create a new Object
ID = Integer.parseInt(dbResult.getString("sensorID") );
        NAME = dbResult.getString("sensorName");    
        COMMENTS = dbResult.getString("sensorcomments");

        //create a new sensor object
        Sensor newSensor = new Sensor(ID, NAME, COMMENTS);

        //add the sensor to the list
        addSensor(newSensor);

` The problem that i am having is that i can add the Sensor Object to the Linked List but when I try to loop through it i get a reference as a result instead of the object or its values.

//display the results of the Linked List
System.out.println(Arrays.toString(sensors.toArray()));

the output that I get is [Sensor@4d405ef7, Sensor@6193b845, Sensor@2e817b38, Sensor@c4437c4, Sensor@433c675d, Sensor@3f91beef]

Thank you

回答1:

You need a toString() method in your Sensor class.

@Override
public String toString() {
    return "id: "+ID+"; name: "+NAME+"; comments: "+ COMMENTS;
}

Arrays.toString(Object[] a) will call each of your Sensor object's toString() method.

Here's a more complete example of a Sensor class with recommended variable name changes:

class Sensor {

    private int id;
    private String name;
    private String comments;

    public Sensor(int id, String name, String comments) {
        this.id = id;
        this.name = name;       
        this.comments = comments;
    }

    @Override
    public String toString() {
        //You can change how to the string is built in order to achieve your desired output.
        return "id: "+ID+"; name: "+name+"; comments: "+ comment;
    }

}

来源：https://stackoverflow.com/questions/28994299/how-to-iterate-through-linkedlist-that-contains-object-java

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java

arrays

tostring