HashMap return method

Question

I have a method in a class, which initialize a HashMap and put some keys and values inside it, then the method returns the HashMap. How can I retrieve the returned HashMap?

public Map<String, String> getSensorValue(String sensorName) {
    registerSensor(sensorName);
    sensorValues.put("x","25");
    sensorValues.put("y","26");
    sensorValues.put("z","27");
    return sensorValues;
}

And here I call this method from another class:

public static HashMap<String, String> sensValues = new HashMap<String, String>();

AllSensors sensVal = new AllSensors();
sensValues.putAll(sensVal.getSensorValue("orientation"));
String something = sensValues.get("x");

But it does not work in this way

sensValues.putAll(sensVal.getSensorValue("orientation"));

Makes my android application crash. The point is to retrive returned HashMap somehow.

Answer 1

You shouldn't have to copy the map. Just try using the returned reference:

Map<String, String> map = sensVal.getSensorValue("...");

Answer 2

Your method needs to return a Map<String,String>. In the code you have posted, the Map sensorValues is never initialized.

public Map<String, String> getSensorValue(String sensorName) {
    Map<String,String> sensorValues = new HashMap<String,String>();
    registerSensor(sensorName);
    sensorValues.put("x","25");
    sensorValues.put("y","26");
    sensorValues.put("z","27");
    return sensorValues;
}