1.使用application来保存全局变量
这里没有太多理论性的东西，无非就是一些实际操作。
1.1定义Data类继承Application Data.class
import android.app.Application; public class Data extends Application{ private String b; public String getB(){ return this.b; } public void setB(String c){ this.b= c; } @Override public void onCreate(){ b = "hello"; super.onCreate(); } }
1.2在manifest.xml中声明application
android:name="com.animator1.Data" >
1.3创建两个Activity
MainActivity.class
public class MainActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); Button btn = (Button) this.findViewById(R.id.button1); final TextView txtview = (TextView) this.findViewById(R.id.main); final Data app = (Data)getApplication(); txtview.setText(app.getB()); btn.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub app.setB("no_hello"); txtview.setText(app.getB()); Intent intent = new Intent(MainActivity.this, secondActivity.class); startActivity(intent); } }); } }
secondActivity.class
public class secondActivity extends Activity{ @Override protected void onCreate(Bundle savedInstanceState){ super.onCreate(savedInstanceState); setContentView(R.layout.second); Button btn = (Button) this.findViewById(R.id.button2); final TextView txtview = (TextView) this.findViewById(R.id.second); final Data app = (Data)getApplication(); txtview.setText(app.getB()); btn.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub app.setB("hello"); txtview.setText(app.getB()); Intent intent = new Intent(secondActivity.this, MainActivity.class); startActivity(intent); } }); } }
1.4运行程序
说明：程序首先进入MainActivity.class中，获取Data中变量b的值，显示图1所示的界面hello，单击button后app.setB("no_hello")， 修改变量b的值。
跳转到secondActivity.class，获取Data中变量b的值，显示图2所示的界面no_hello，单击button后app.setB("hello")， 修改变量b的值。
跳转回MainActivity.class…… 循环
2.使用普通的类Data.class来保存全局变量
方法和上面差不多。
1.1 定义Data.class
public class Data{ private static String a ="feiyangxiaomi"; public static String getA() { return a; } public static void setA(String a) { Data.a = a; } }
1.2创建两个Activity
MainActivity.class
public class MainActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); Button btn = (Button) this.findViewById(R.id.button1); final TextView txtview = (TextView) this.findViewById(R.id.main); txtview.setText(Data.getA()); btn.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub Data.setA("no_feiyangxiaomi"); Intent intent = new Intent(MainActivity.this, secondActivity.class); startActivity(intent); } }); } }
secondActivity.class
public class secondActivity extends Activity{ @Override protected void onCreate(Bundle savedInstanceState){ super.onCreate(savedInstanceState); setContentView(R.layout.second); Button btn = (Button) this.findViewById(R.id.button2); final TextView txtview = (TextView) this.findViewById(R.id.second); txtview.setText(Data.getA()); btn.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub Data.setA("feiyangxiaomi"); Intent intent = new Intent(secondActivity.this, MainActivity.class); startActivity(intent); } }); } }
1.3运行程序
说明：程序首先进入MainActivity.class中，获取Data中变量b的值，显示图1所示的界面feiyangxiaomi，单击button后app.setB("no_feiyangxiaomi")， 修改变量b的值。
跳转到secondActivity.class，获取Data中变量b的值，显示图2所示的界面no_feiyangxiaomi，单击button后app.setB("feiyangxiaomi")， 修改变量b的值。
跳转回MainActivity.class…… 循环
3.总结
两种方法我测试的都可以的，大多数人应该更会偏向于第一种，毕竟Application是android专门提供的应用入口，并且运行周期贯穿整个程序运行。
摘自
