来自另一个类的 Android 调用意图

Question

我在我的程序中调用了很多意图，我认为我可以编写一个包含我所有意图的公共类，这样我就可以调用类似 intents.testIntent(params) 之类的东西，然后让它触发意图。

我试过了，但由于空指针异常而强制关闭。这是我的整个班级。我知道这可能很草率，但我刚刚学习 java 2 个月，所以我还是个业余爱好者。

无论如何，我的代码如下，非常感谢您的帮助。

    public class intents extends Activity{
     String classpkg = "com.MyApp";

     public void onCreate(Bundle savedInstanceState) {


            super.onCreate(savedInstanceState);
     } 
     public void testIntent(String name, String match){
      Log.v("AI","made It");
      Intent myIntent = new Intent();

      myIntent.setClassName(classpkg, classpkg+".Search");
      Log.v("AI","Launching Intent"); //This is where it dies
      startActivity(myIntent);
      Log.v("AI","Launced Intent");

     }

}

日志

  /AI      (17056): made It
V/AI      (17056): Launching Intent
D/AndroidRuntime(17056): Shutting down VM
W/dalvikvm(17056): threadid=3: thread exiting with uncaught exception (group=0x4001b180)
E/AndroidRuntime(17056): Uncaught handler: thread main exiting due to uncaught exception
E/AndroidRuntime(17056): java.lang.NullPointerException
E/AndroidRuntime(17056): at android.app.Activity.startActivityForResult(Activity.java:2749)
E/AndroidRuntime(17056): at android.app.Activity.startActivity(Activity.java:2855)
E/AndroidRuntime(17056): at com.MyApp.intents.testIntent(intents.java:26)
E/AndroidRuntime(17056): at com.MyApp.Starting$1.onClick(Starting.java:52)
E/AndroidRuntime(17056): at android.view.View.performClick(View.java:2364)
E/AndroidRuntime(17056): at android.view.View.onTouchEvent(View.java:4179)
E/AndroidRuntime(17056): at android.widget.TextView.onTouchEvent(TextView.java:6541)
E/AndroidRuntime(17056): at android.view.View.dispatchTouchEvent(View.java:3709)
E/AndroidRuntime(17056): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884)
E/AndroidRuntime(17056): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884)
E/AndroidRuntime(17056): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884)
E/AndroidRuntime(17056): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884)
E/AndroidRuntime(17056): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884)
E/AndroidRuntime(17056): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884)
E/AndroidRuntime(17056): at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1659)
E/AndroidRuntime(17056): at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1107)
E/AndroidRuntime(17056): at android.app.Activity.dispatchTouchEvent(Activity.java:2061)
E/AndroidRuntime(17056): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1643)
E/AndroidRuntime(17056): at android.view.ViewRoot.handleMessage(ViewRoot.java:1691)
E/AndroidRuntime(17056): at android.os.Handler.dispatchMessage(Handler.java:99)
E/AndroidRuntime(17056): at android.os.Looper.loop(Looper.java:123)
E/AndroidRuntime(17056): at android.app.ActivityThread.main(ActivityThread.java:4363)
E/AndroidRuntime(17056): at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(17056): at java.lang.reflect.Method.invoke(Method.java:521)
E/AndroidRuntime(17056): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
E/AndroidRuntime(17056): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
E/AndroidRuntime(17056): at dalvik.system.NativeStart.main(Native Method)

解决方案： 一个解决方案，也许不是解决方案。是在意图类（重命名为 MyIntents）中构建意图，然后从我的其他类开始。

MyIntents intents1  = new MyIntents();
Intent arIntent = intents1.testIntent("fe", "feet");
startActivity(arIntent);

这将使我的生活更轻松。 :)

Answer 1

我认为您正在做的事情（类名的字符串，每次需要意图时都实例化一个辅助类）很混乱。
我建议有一个带有工厂方法的辅助类，如下所示：

public static final String FIRST_NAME = "first_name";

public static Intent getNameIntent(Context ctx, String firstName) {
    Intent intent = new Intent(ctx, NameActivity.class);
    intent.putExtra(FIRST_NAME, firstName);
    return intent;
}

然后来自Activity:

    Intent intent = getNameIntent(this, "alex");
    startActivity(intent);
    // or
    startActivityForResult(intent, 1024);