java final本质详解

package com.dada.data;

 

public class TestFinal {

  // 1.声明时赋值

  private final int i = 0;

  private final int j;

  public TestF() {

    // 2.构造方法中赋值

    j = 10;

  }

}

package com.dada.data;

 

public class Student {

  private int id;

  private String name;

  private int score;

  public Student(int id, String name, int score) {

    this.id = id;

    this.name = name;

    this.score = score;

  }

  public int getId() {

    return id;

  }

  public void setId(int id) {

    this.id = id;

  }

  public String getName() {

    return name;

  }

  public void setName(String name) {

    this.name = name;

  }

   

  public int getScore() {

    return score;

  }

  public void setScore(int score) {

    this.score = score;

  }

   

  @Override

  public String toString() {

    return "id: " + id + "\t name:" + name + "\tscore:" + score;

  }

}

package com.dada.data;

 

public class TestFinal {

  private final Student ss;

   

  public static void main(String[] args) {

    TestFinal tf = new TestFinal();

  }

  public TestFinal() {

    Student student = new Student(1, "dada", 3);

    // 第一次赋值

    ss = student;

    System.out.println(ss.toString());

     

    // 修改引用所对应的对象的内容

    student.setId(2);

    student.setName("hehe");

    student.setScore(10);

    System.out.println(ss.toString());

  }

}

id: 1   name:dada  score:3

id: 2   name:hehe  score:10