java - How do I inherit variables from specific instance of a superclass?

Question

If I create several instances of a superclass, where their state is set to arbitrary values by the class constructor, how can I make sure a subclass inherits its state from a specific instance of the superclass?

Answer 1

サブクラスの各インスタンスには、そのスーパークラスの独自のインスタンスがあります。そう：

public class Super
{
    protected int x;
    public Super( int x ) { this.x = x; }
}

public class Sub
{
    public Sub( int x ) { super( x ); }
    public void func() { System.out.println( x ); }

    public static void main( String[] args )
    {
        Sub a, b;
        a = new Sub( 1 );
        b = new Sub( 2 );
        a.func(); b.func();
    }
}

これは出力されます

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