JAVA EXAMPLE PROGRAMS

JAVA EXAMPLE PROGRAMS

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Program: How to get all keys from properties file?


Description:

This example shows how to get all keys from the given properties file. All keys will be returned in the form of set object. You can get it by calling keySet() method.


Code:
package com.java2novice.properties;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
import java.util.Set;

public class MyPropAllKeys {

	private Properties prop = null;
	
	public MyPropAllKeys(){
		
		InputStream is = null;
		try {
			this.prop = new Properties();
			is = this.getClass().getResourceAsStream("/sample.properties");
			prop.load(is);
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	
	public Set<Object> getAllKeys(){
		Set<Object> keys = prop.keySet();
		return keys;
	}
	
	public String getPropertyValue(String key){
		return this.prop.getProperty(key);
	}
	
	public static void main(String a[]){
		
		MyPropAllKeys mpc = new MyPropAllKeys();
		Set<Object> keys = mpc.getAllKeys();
		for(Object k:keys){
			String key = (String)k;
			System.out.println(key+": "+mpc.getPropertyValue(key));
		}
	}
}

sample.properties
db.host=appdomain.java2novice.com
db.user=java2novice
db.password=mypassword
db.service=orcl

Output:
db.password: mypassword
db.user: java2novice
db.host: appdomain.java2novice.com
db.service: orcl
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List of Properties class sample programs:

  1. How to load Properties file from a file system?
  2. How to load Properties file from the classpath?
  3. How to load Properties file from a static block or static method?
  4. How to assign default values for unavailable keys in properties file?
  5. How to get all keys from properties file?
  6. How to create and store property file dynamically?
  7. How to store property file as xml file?
  8. How to load property file using class name in java?
Knowledge Centre
wait Vs sleep methods
sleep(): It is a static method on Thread class. It makes the current thread into the "Not Runnable" state for specified amount of time. During this time, the thread keeps the lock (monitors) it has acquired.

wait(): It is a method on Object class. It makes the current thread into the "Not Runnable" state. Wait is called on a object, not a thread. Before calling wait() method, the object should be synchronized, means the object should be inside synchronized block. The call to wait() releases the acquired lock.
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About Author

I'm Nataraja Gootooru, programmer by profession and passionate about technologies. All examples given here are as simple as possible to help beginners. The source code is compiled and tested in my dev environment.

If you come across any mistakes or bugs, please email me to [email protected].

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Reference: Java™ Platform Standard Ed. 7 - API Specification | Java™ Platform Standard Ed. 8 - API Specification | Java is registered trademark of Oracle.
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