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how to set the value of the Integer instance?

how to set the value of the Integer instance? for example, how to make the following Update work ?

class m
{
public static void Update(Integer i)
{
// how to update the value of i to some arbitrary value
// say, 999, i = new Integer(999) won't work.
}
}

yuri1976

this won't work because you can't change the reference of the external value i. This is what you do when you say i = new Integer(999).
And as Integer is a immutable class (you can't change the contents), you can't change the value of i also. The only way to do such a action is to calculate the new value and return it.

public static Integer Update(Integer i) {
// do your calculations on i
// and return the result
return new Integer(999);
}

isond

You need to make i a class variable not a parameter.

try this

class mytest
{

private Integer i=new Integer(5);

public void Update()
{
this.i=new Integer(999);
}

public Integer getVal()
{
return this.i;
}

}

Then call the class using code similar to the following.

public static void main(String args[])
{
mytest m = new mytest();
Integer i = m.getVal();
System.out.println("i=" + i.toString());
m.Update();
i = m.getVal();
System.out.println("i=" + i.toString());

}
}

Hope this helps.

Darren.

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yongsing

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eugeneng

ASKER

so, is String an immutable class also ?

eugeneng

ASKER

so, is String an immutable class also ?