/**
*   Klasa posiadajaca zmienne globalne
*/
package com.example.apps;

import android.app.Application;

public class Globals extends Application {

    private String str;

    public String getStr() {
        return str;
    }

    public void setStr(String str) {
        this.str = str;
    }
}

/**
*   Klasa ustawiajaca wartosc dla zmiennej globalnej
*/
public class CustomVar extends Activity {

    private Button btn;
    Globals g;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_setters);

        g = ((Globals)getApplicationContext());


        btn = (Button)findViewById(R.id.btnSets);
        btn.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                g.setStr("test");

            }
        });
    }
}

/**
*   Główna klasa
**/

public class MainActivity extends Activity {

    private Button btn2;
    private TextView tv;
    private Button btn3;
    private Globals g;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        g = ((Globals)getApplicationContext());

        tv = (TextView)findViewById(R.id.textView1);
        btn2 = (Button)findViewById(R.id.btnGet);
        btn2.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                tv.setText(g.getStr());

            }
        });


        btn3 = (Button)findViewById(R.id.btn3);
        btn3.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                Intent i = new Intent(getApplicationContext(), Setters.class);
                startActivity(i);

            }
        });
    }
}

/**
*   manifest
*/
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.apps"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="17" />

    <application
        android:name="com.example.apps.Globals"
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.apps.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity
            android:name="com.example.apps.CustomVar"
            android:label="@string/title_activity_setters" >
        </activity>
        <activity
            android:name="com.example.apps.Second"
            android:label="@string/title_activity_second" >
        </activity>
    </application>

</manifest>