Dúvida sobre Interface

[Bieh]

Estou começando a estudar Java e optei por seguir o tutorial que o próprio site oficial oferece (ainda que em Inglês). Em uma das atividades eu deveria construir uma interface para meus objetos, mas não consegui fazê-lo. A falta de um exemplo na resolução do problema também me deixou mais perdido ainda. Enfim, eu uso o NetBeans, e eis o código do que fiz até agora:

 

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package exercises;

/**
 *
 * @author ASUS
 */

interface PessoaInterface {
    public void changename(String text);
    public void changeage(int value);
}    
public class Pessoa implements PessoaInterface {
    String name = "";
    int age = 0;
    
    public void changename(String text) {
        name = text;
    }
    
    public void changeage(int value) {
        age = value;
    }
    
    void print() {
        System.out.println(name + "is " + age + "years old.");
    }
}
public class exercises {
    Pessoa Ana = new Pessoa();
    Pessoa Michel = new Pessoa();
    Pessoa Victoria = new Pessoa();
    
    Ana.changename("Ana");
    Michel.changename("Michel");
    Victoria.changename("Victoria");
    
    Ana.changeage(12);
    Michel.changeage(17);
    Victoria.changeage(17);
    
    Ana.print();
    Michel.print();
    Victoria.print();
    
    
}

 

Alguém pode me dizer o que fiz de errado? Eu passei um bom tempo procurando mas não entendi o motivo do erro. Aliás, a caixa de saída:

 

Created dir: C:\Users\ASUS\Documents\NetBeansProjects\Exercises\build
Updating property file: C:\Users\ASUS\Documents\NetBeansProjects\Exercises\build\built-jar.properties
Created dir: C:\Users\ASUS\Documents\NetBeansProjects\Exercises\build\classes
Created dir: C:\Users\ASUS\Documents\NetBeansProjects\Exercises\build\empty
Created dir: C:\Users\ASUS\Documents\NetBeansProjects\Exercises\build\generated-sources\ap-source-output
Compiling 1 source file to C:\Users\ASUS\Documents\NetBeansProjects\Exercises\build\classes
C:\Users\ASUS\Documents\NetBeansProjects\Exercises\src\exercises\exercises.java:38: error: <identifier> expected
    Ana.changename("Ana");
C:\Users\ASUS\Documents\NetBeansProjects\Exercises\src\exercises\exercises.java:38: error: illegal start of type
    Ana.changename("Ana");
C:\Users\ASUS\Documents\NetBeansProjects\Exercises\src\exercises\exercises.java:39: error: <identifier> expected
    Michel.changename("Michel");
C:\Users\ASUS\Documents\NetBeansProjects\Exercises\src\exercises\exercises.java:39: error: illegal start of type
    Michel.changename("Michel");
C:\Users\ASUS\Documents\NetBeansProjects\Exercises\src\exercises\exercises.java:40: error: <identifier> expected
    Victoria.changename("Victoria");
C:\Users\ASUS\Documents\NetBeansProjects\Exercises\src\exercises\exercises.java:40: error: illegal start of type
    Victoria.changename("Victoria");
C:\Users\ASUS\Documents\NetBeansProjects\Exercises\src\exercises\exercises.java:42: error: <identifier> expected
    Ana.changeage(12);
C:\Users\ASUS\Documents\NetBeansProjects\Exercises\src\exercises\exercises.java:42: error: illegal start of type
    Ana.changeage(12);
C:\Users\ASUS\Documents\NetBeansProjects\Exercises\src\exercises\exercises.java:43: error: <identifier> expected
    Michel.changeage(17);
C:\Users\ASUS\Documents\NetBeansProjects\Exercises\src\exercises\exercises.java:43: error: illegal start of type
    Michel.changeage(17);
C:\Users\ASUS\Documents\NetBeansProjects\Exercises\src\exercises\exercises.java:44: error: <identifier> expected
    Victoria.changeage(17);
C:\Users\ASUS\Documents\NetBeansProjects\Exercises\src\exercises\exercises.java:44: error: illegal start of type
    Victoria.changeage(17);
C:\Users\ASUS\Documents\NetBeansProjects\Exercises\src\exercises\exercises.java:46: error: <identifier> expected
    Ana.print();
C:\Users\ASUS\Documents\NetBeansProjects\Exercises\src\exercises\exercises.java:47: error: <identifier> expected
    Michel.print();
C:\Users\ASUS\Documents\NetBeansProjects\Exercises\src\exercises\exercises.java:48: error: <identifier> expected
    Victoria.print();
15 errors
C:\Users\ASUS\Documents\NetBeansProjects\Exercises\nbproject\build-impl.xml:929: The following error occurred while executing this line:
C:\Users\ASUS\Documents\NetBeansProjects\Exercises\nbproject\build-impl.xml:269: Compile failed; see the compiler error output for details.
FALHA NA CONSTRUÇÃO (tempo total: 31 segundos)

 

Editado Novembro 12, 2016 por Bieh
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