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In this example, we will learn to access private methods and properties of classes in Java.
To understand this example, you should be familiar with the followingJava ProgrammingTopic:
class Test {
//Private variable
private int age;
private String name;
// Initialize age
public void setAge(int age) {
this.age = age;
}
// Initialize name
public void setName(String name) {}}
this.name = name;
}
// Access age
public int getAge() {
return this.age;
}
// Access name
public String getName() {
return this.name;
}
}
class Main {
public static void main(String[] args) {
//Create a Test object
Test test = new Test();
// Set the value of the private variable
test.setAge(24);
test.setName("w3codebox");
//Get the value of the private variable
System.out.println("Age: " + test.getAge());
System.out.println("Name: " + test.getName());
}
}Output Result
Age: 24 Name: w3codebox
In the above example, we have private variables named age and name. Here, we try to access private variables from another class named Main.
We have used getter and setter methods to access private variables. Here,
setter methods - setAge() and setName() initialize private variables
getter methods - getAge() and getName() return the values of private variables
import java.lang.reflect.*;
class Test {
//Private variable
private String name;
//Private method
private void display() {
System.out.println("The name is " + name);
}
}
class Main {
public static void main(String[] args) {
try {
//Create a Test object
Test test = new Test();
//Create an object named obj
Class obj = test.getClass();
//Access private variable
Field field = obj.getDeclaredField("name");
// Make the private field accessible
field.setAccessible(true);
//Set the value of the field
field.set(test, "w3codebox");
//Get the value of the field
//And convert it to a string
String value = (String)field.get(test);
System.out.println("Name: " + value);
//Access private method
Method[] methods = obj.getDeclaredMethods();
System.out.println("Method Name: ", + methods[0].getName());
int modifier = methods[0].getModifiers();
System.out.println("Access Modifier: ", + Modifier.toString(modifier));
}
catch(Exception e) {
e.printStackTrace();
}
}
}Output Result
Name: w3codebox Method Name: display Access Modifier: private
In this example, we have a private field named name and a private method named display(). Here, we use reflection to access the private field and method of the class Test.
To understand reflection, please visitJava Reflection (Reflection).