java - 摆脱对象的引用

我想摆脱测试器类中每个对象的引用，但出现错误。我使用的方法已在注释中提供给我，但不确定它们是否正确。

任何帮助将不胜感激 ：）

这是我的代码：

public class Bicycle {

// Instance Variables
private String name; // Owner's name
private int age; // Owner's age
private char gender; // Owner's gender
private static int instanceCounter = 0;

// Default Constructor - doesn't take in values
public Bicycle() {
    this("Not Given", 0, 'U');
    instanceCounter++;
}

// Parameter constructor
public Bicycle(String name, int age, char gender) {
    this.name = name;
    this.age = age;
    this.gender = gender;
    instanceCounter++;
}

// Getter and setters
public String getName() {
    return name;
}
public void setName(String name) {
    this.name = name;
}

public int getAge() {
    return age;
}
public void setAge(int age) {
    this.age = age;
}

public char getGender() {
    return gender;
}
public void setGender(char gender) {
    this.gender = gender;
}

public int countInstances(){
    return instanceCounter;
}
}

测试人员：

public class BicycleTester {

  public static void main(String args[]){


    // Instance one
    Bicycle bicycle1 = new Bicycle(null, 0, 'U');
    bicycle1.setName("John");
    System.out.println("Name: " +bicycle1.getName());
    bicycle1.setAge(18);
    System.out.println("Age: " +bicycle1.getAge());
    bicycle1.setGender('M');
    System.out.println("Gender: " +bicycle1.getGender());

    System.out.println("");

    // Instance two
    Bicycle bicycle2 = new Bicycle(null, 0, 'U');
    bicycle2.setName("Mary");
    System.out.println("Name: " +bicycle2.getName());
    bicycle2.setAge(23);
    System.out.println("Age: " +bicycle2.getAge());
    bicycle2.setGender('F');
    System.out.println("Gender: " +bicycle2.getGender());

    System.out.println("");

    // Instance three
    Bicycle bicycle3 = new Bicycle(null, 0, 'U');
    bicycle3.setName("Billy");
    System.out.println("Name: " +bicycle3.getName());
    bicycle3.setAge(15);
    System.out.println("Age: " +bicycle3.getAge());
    bicycle3.setGender('M');
    System.out.println("Gender: " +bicycle3.getGender());

    System.out.println("");

    // Three ways to get rid of object's reference
    void go() {
        Life bicycle1 = new Life();
    }

    Life bicycle2 = new Life();
    bicycle2 = new Life();

    Life bicycle3 = new Life();
    bicycle3 = null;

}

}

最佳答案

好吧，女士，让我们再看一遍基础知识。

我们将从对象AKA实例和引用之间的区别开始。

Life bicycle2 = new Life();

在这里，bicycle2是引用，它将在堆栈中。该引用指向通过调用instance创建的new Life()。该实例将在堆上

您不能摆脱对象的引用。您可以摆脱一个实例。
只有一种方法可以做到这一点。


将指向实例的引用设置为null或to some other instance
示例：Life bicycle2 = new Life();
       bicycle2 = null;// the instance created above will be eligible for GC


或者您也可以这样做：

Life bicycle2 = new Life();
bicycle2 = new Life(); //上面创建的生命实例将被丢弃。

请注意：引用一旦超出范围就会依赖于范围，将无法访问。我不认为您在这里谈论这个话题。