How to use Java Enum with Android studio

Content
1. What is Enum in Java?
2. Enum use in If Statement
3. Enum use in Switch Statement
4. Enum field
5. Enum method
6. Enum Iteration

1. What is enum? 
An Enum in Java is:
- A special data type that enables for a variable to be a set of predefined constants.
- Its variable must be equal to one of the values that have been predefined for it.
- Enum able to contain field and method, etc and it was added in Java 5.

Example:

2. Enum use in If Statement
Developers like to enum to store constants variable for comparing by using If or Switch statement. So let's see enum as If Statement, we have Country enum that contains 3 fields:

	package rpek.enumdemo.enam;
	/**
	* Created by r.pek on 02.10.2017.
	*/
	public enum Country {
	PHNOM_PENH,
	KOREA,
	JAPAN
	}

view raw Country.java hosted with ❤ by GitHub

If Statement:

	//Initilize value with JAPAN
	//So It will print JAPAN on textview
	Country countryType = JAPAN;
	//If statement
	if(countryType.equals(Country.PHNOM_PENH)){
	tvResult.setText(PHNOM_PENH+"");
	}else if(countryType.equals(Country.JAPAN)){
	tvResult.setText(JAPAN+"");
	}else if(countryType.equals(Country.KOREA)){
	tvResult.setText(KOREA+"");
	}

view raw If.java hosted with ❤ by GitHub

3. Enum use in Switch Statement
Here is a sample, I had initialized it value "JAPAN". So our enum will run and check each value (PHNOM_PENH, JAPAN, KOREA). JAPAN's case will be true so it will set TextView to JAPAN on the screen.

	//Initilize value with JAPAN
	//So It will print JAPAN on textview
	Country countryType = JAPAN;
	//reference to xml to display result from java code
	tvResult= (TextView) findViewById(R.id.tvResult);
	switch (countryType){
	case PHNOM_PENH:
	tvResult.setText(PHNOM_PENH+"");
	break;
	case JAPAN:
	tvResult.setText(JAPAN+"");
	break;
	case KOREA:
	tvResult.setText(KOREA+"");
	break;
	}

view raw switch.java hosted with ❤ by GitHub

4. Enum Field
We have 3 constructors that have each default value,  if you use like this, it will return the default value, it has fruit field:

Fruit.APPLE.getFruit()// LIKE

Fruit.PINE_APPLE.getFruit()//DON'T LIKE

Fruit.BANANA.getFruit()//NORMAL

	//we can user setter & getter with enum
	Fruit.APPLE.setFruit("YES, Love APPLE");
	Fruit.PINE_APPLE.setFruit("NO, DON'T LIKE");
	Fruit.BANANA.setFruit("NORMAL BANANA");
	tv.setText(Fruit.APPLE.getFruit()+"");

view raw field.java hosted with ❤ by GitHub

5. Enum Method
For enum method you can set/get the value from fruit fields like below:



6. Enum Iteration

	//How to do enum iteration
	StringBuilder concateString=new StringBuilder();
	for(Country country: Country.values()){
	concateString.append(country+ "\n");
	}
	tvResult.setText(concateString);

view raw iteration.java hosted with ❤ by GitHub

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