更改字段的值

 

 

public class ClassInit {
    private Person person=new Person("test", "test1");
    private Person[] flock =new Person[]{ person };

    public ClassInit() {
        for (int i = 0; i < flock.length; i++) {
            flock[i] = new Person(i+"name",i+"Id");
        }
    }

    public void print() {
        System.out.println(person);
    }

    public void printArray() {
        for (Person person : flock) {
            System.out.println(person);
        }
    }

    public static void main(String[] args) {
        ClassInit self = new ClassInit();
        self.print();
        self.printArray();
    }

}

class Person {
    private String name;
    private String id;

    public Person(String name, String id) {
        super();
        this.name = name;
        this.id = id;
    }

    @Override
    public String toString() {
        return this.name + ":" + this.id;
    }

}

 

Output:

test:test1
0name:0Id

现象：
person的值没有改变

变形1：结果和上例相同

public class ClassInit {
    
    public static void main(String[] args) {
        Flock flock = new Flock();
        flock.print();
        flock.printArray();
    }
}



class Flock {
    private Person person=new Person("test", "test1");
    private Person[] flock =new Person[]{ person };

    public Flock() {
        for (int i = 0; i < flock.length; i++) {
            flock[i] = new Person(i+"name",i+"Id");
        }
    }

    public void print() {
        System.out.println(person);
    }

    public void printArray() {
        for (Person person : flock) {
            System.out.println(person);
        }
    }



}

class Person {
    private String name;
    private String id;

    public Person(String name, String id) {
        super();
        this.name = name;
        this.id = id;
    }

    @Override
    public String toString() {
        return this.name + ":" + this.id;
    }

}

 

 

变形2：结果和上例相同

import java.util.ArrayList;
import java.util.List;

public class ClassInit {
    
    public static void main(String[] args) {
        Flock flock = new Flock();
        flock.print();
        flock.printArray();
    }
}



class Flock {
    private Person person=new Person("test", "test1");
    private List<Person> flock =new ArrayList<Person>();

    public Flock() {
        flock.add(person);
        for (int i = 0; i < flock.size(); i++) {
            flock.set(i, new Person(i+"name",i+"Id"));
        }
    }

    public void print() {
        System.out.println(person);
    }

    public void printArray() {
        for (Person person : flock) {
            System.out.println(person);
        }
    }



}

class Person {
    private String name;
    private String id;

    public Person(String name, String id) {
        super();
        this.name = name;
        this.id = id;
    }

    @Override
    public String toString() {
        return this.name + ":" + this.id;
    }

}