java - 在上一个 Activity 中如何访问数据？

使用StartActivity我从FirstActivity到达了SecondActivity。现在，我想访问上一个活动中声明的对象。

我是否缺少任何明显的机制。我无法在要传递的对象（DropboxAPI）上使用Parceable，因为我没有其来源（我无法将其设为parceable）。

我可以通过意图使它成为Parceable吗？我可以通过FirstActivity.this吗？

    Intent intent=new Intent(FirstActivity.this,SecondActivity.class);
    intent.putExtra("MyClass",FirstActivity.this);
    startActivity (intent);

import com.dropbox.client2.DropboxAPI;
import com.dropbox.client2.android.AndroidAuthSession;

import android.app.Application;
import android.hardware.Camera.Parameters;
import android.os.Parcel;
import android.os.Parcelable;
public class temp extends Application {

    DropboxAPI<AndroidAuthSession> mApi;
    public void onCreate() {
        super.onCreate();
    }

    temp(DropboxAPI<AndroidAuthSession> Api)
    {
        mApi=Api;
    }
    public DropboxAPI<AndroidAuthSession> getName() {
        return mApi;
}
    public void setName(DropboxAPI<AndroidAuthSession> dropboxclient) {
        this.mApi = dropboxclient;
}
}

一流的代码：

t = (temp)getApplication();
                t.setName(mApi);
                //basket.putParcelable("key", MCActivity.this);
                Intent intent=new Intent(MCActivity.this,DownActivity.class);
                //intent.putExtra("MyClass",t);
                startActivity (intent);

第二类代码：

public void onCreate(Bundle bun) {

    // TODO Auto-generated method stub
    super.onCreate(bun);
    setContentView(R.layout.download);
    mImage = (ImageView)findViewById(R.id.image_view);
    //Bundle gotit=getIntent().getExtras();
    t = (temp)getApplication();
    int i=2;
    i=5;
    dApi=t.getName();
}

Logcat：

06-28 02:24:31.979: I/System.out(729): debugger has settled (1308)
06-28 02:25:08.387: D/AndroidRuntime(729): Shutting down VM
06-28 02:25:08.387: W/dalvikvm(729): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
06-28 02:25:08.705: E/AndroidRuntime(729): FATAL EXCEPTION: main
06-28 02:25:08.705: E/AndroidRuntime(729): java.lang.ClassCastException: android.app.Application
06-28 02:25:08.705: E/AndroidRuntime(729):  at cloud.mobile.MCActivity$3.onClick(MCActivity.java:164)
06-28 02:25:08.705: E/AndroidRuntime(729):  at android.view.View.performClick(View.java:2408)
06-28 02:25:08.705: E/AndroidRuntime(729):  at android.view.View$PerformClick.run(View.java:8816)
06-28 02:25:08.705: E/AndroidRuntime(729):  at android.os.Handler.handleCallback(Handler.java:587)
06-28 02:25:08.705: E/AndroidRuntime(729):  at android.os.Handler.dispatchMessage(Handler.java:92)
06-28 02:25:08.705: E/AndroidRuntime(729):  at android.os.Looper.loop(Looper.java:123)
06-28 02:25:08.705: E/AndroidRuntime(729):  at android.app.ActivityThread.main(ActivityThread.java:4627)
06-28 02:25:08.705: E/AndroidRuntime(729):  at java.lang.reflect.Method.invokeNative(Native Method)
06-28 02:25:08.705: E/AndroidRuntime(729):  at java.lang.reflect.Method.invoke(Method.java:521)
06-28 02:25:08.705: E/AndroidRuntime(729):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
06-28 02:25:08.705: E/AndroidRuntime(729):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
06-28 02:25:08.705: E/AndroidRuntime(729):  at dalvik.system.NativeStart.main(Native Method)

最佳答案

尝试使用Application类：

public class MyApplication extends Application {
    //Variable we want to share to All Activities in Application

    private DropboxClient dropboxclient;

    @Override
    public void onCreate() {
            super.onCreate();

    }
    //Getter Method
    public DropboxClient getName() {
            return dropboxclient;
    }
    //Setter Method
    public void setName(DropboxClient dropboxclient) {
            this.dropboxclient = dropboxclient;
    }
}

在MyFirstActivity活动中：

private MyApplication app;
@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        app = (MyApplication)getApplication();  //Get  Application
        app.setName(dropboxclient);
        Intent intent = new Intent();
        intent.setClass(this, MySecondActivity.class);
        startActivity(intent);

在MySecondActivity活动中：

private MyApplication app;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            app = (MyApplication)getApplication();  //Get  Application
            DropboxClient dropboxclient=app.getName();//Access global value