How to call a non-static method from a static method

Question

Possible Duplicate:
calling non-static method in static method in Java

Is it possible to call a non-static method from a static method? The non-static is located in another class and it have to be non-static.

    public static void start() {
        CheckConnection checkInternet = new CheckConnection();
        if (checkInternet.isNetworkAvailable()) {
            // Has internet Connection
            } else {
            // No Internet Connection
        }
 }

The code doesn't give any errors in Eclipse (Android 4.0.4) but if I run it my application freezes and closes.

Yes it's possible (it would not compile if not). And it is not the reason why it freezes. More likely the `isNetworkAvailable()` method freezes for some other reasons. — assylias, Oct 19 '12 at 11:44
or the c'tor of CheckConnection. Looking on the stacktrace when running in debug mode can unveil the problem. — IllegalArgumentException, Oct 19 '12 at 11:47
In a java program (not specifically android) Main is a static method.. :) .. and it calls everything. so the answer to your title is yes. like all guys are suggesting here something else is going on. @AndroSelva it's not a duplicate, the question is not related to the title that's all — quinestor, Oct 19 '12 at 11:47

score 5 · Accepted Answer · answered Oct 19 '12 at 11:45

5

The only way to call a non-static method from a static method is you should have
an instance of the class containing the non-static method.

Like in your question :

 CheckConnection checkInternet = new CheckConnection();
    if (checkInternet.isNetworkAvailable()) {
        // Has internet Connection
        } else {
        // No Internet Connection

You have instance of CheckConnection so you can call it.

So there is no problem in your code with non-static method from a static method may be some other thing is responsible for application freezes.

answered Oct 19 '12 at 11:45

Sumit Singh

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Thank you very much! CheckConnection did contain some errors, now I get it! – ObAt Oct 19 '12 at 12:05
your welcome. Do some debugging in that. – Sumit Singh Oct 19 '12 at 12:16

score 1 · Answer 2 · edited Oct 19 '12 at 11:49

1

Yes, this is possible. The problem must lie with your isNetworkAvailable method.

If it were impossible to call non-static methods from static methods, Java applications wouldn't work, since main is itself static.

edited Oct 19 '12 at 11:49

Sumit Singh

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answered Oct 19 '12 at 11:46

Neil Weightman

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4

score 1 · Answer 3 · edited Nov 29 '12 at 11:57

Just create the object of the class that contains non-static method you want to use and then you can call.

For example :

public class Test {
  public static void main(String[] args) {
        System.out.println("This is a static method");
        TestClass class1 = new TestClass();
        class1.nonStatic();
     }
 }

class TestClass{
    public void nonStatic(){
        System.out.println("This is a non-static method");
    }
}

In your problem

public class A{
   public static void start() {
        CheckConnection checkInternet = new CheckConnection();
        if (checkInternet.isNetworkAvailable()) {
            // Has internet Connection
            } else {
            // No Internet Connection
        }
   }
}



public class CheckConnection {
    public boolean isNetworkAvailable()
      {
        //some code
      }
   }

If this is the scenario then it should work.

score 1 · Answer 4 · edited Oct 19 '12 at 11:49

1

Debug into your isNetworkAvailable() method. If possible have a try catch block inside that method and print the stacktrace of exception.

edited Oct 19 '12 at 11:49

Sumit Singh

24,095
8
74
100

answered Oct 19 '12 at 11:47

Sumit Desai

1,455
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19

score 1 · Answer 5 · answered Oct 19 '12 at 11:47

Is it possible to call a non-static method from a static method?

Yes.

Since you have created an object of CheckConnection, you can call the method using it's reference. else it'll be a compile-time error.

but if I run it my application freezes and closes.

Calling non-static method from static context is not the reason. May be reason is within isNetworkAvailable.

How to call a non-static method from a static method

5 Answers5