what does the keyword this does in the code and are there any alternate methods without this keyword?

Question

in the class Student here what does the keyword this used in the functions refer to? what does it return exactly? is it only used in java or c/c++ also? is there any difference if used in any other language?

class Student
{
private String name;
private String section;
public static Comparator BY_NAME = new ByName();
public static Comparator BY_SECTION = new BySection();

public void setName(String name) {
    this.name = name;
}

public void setSection(String section) {
    this.section = section;
}

public String getName()
{
    return this.name;
}

public String getSection()
{
    return this.section;
}

private static class ByName implements Comparator
{
    public int compare(Object s1, Object s2)
    {
        return ((Student)s1).name.compareTo(((Student)s2).name);
    }
}

private static class BySection implements Comparator
{
    public int compare(Object s1, Object s2)
    {
        return ((Student)s1).section.compareTo(((Student)s2).section);
    }
}
}

Answer 1

In Java and c++ "this" is referring to the object's variable and NOT the class's variable.