Question

我有一个自定义弹出窗口，在我的活动中有自己的布局（负责弹出窗口工作的代码在一个单独的类PopupWindowActivity中）。我想在此弹出窗口打开活动中指定一个按钮。我尝试了一些方法，但应用程序崩溃了NullPointerException。

此活动的代码如下：

public class FirstActivity extends Activity implements OnClickListener {

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    ImageView popupButton = (ImageView) this.findViewById(R.id.popup_btn);
    likemenuButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            PopupWindow dw = new PopupWindow(v);
            dw.showLikePopDownMenu();
        }
    });
}

    // my stuff



//popup window
private class PopupWindow extends PopupWindowActivity implements OnClickListener {
    public PopupWindow(View anchor) {
        super(anchor);
    }

    @Override
    protected void onCreate() {
        // inflate layout
        LayoutInflater inflater =
                (LayoutInflater) this.anchor.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);

        ViewGroup root = (ViewGroup) inflater.inflate(R.layout.popup, null);

        // setup button events
        ImageView aboutButton = (ImageView) findViewById(R.id.btn_about);
        aboutButton.setOnClickListener(this);

        this.setContentView(root);
    }

    @Override
    public void onClick(View v) {

        switch (v.getId()) {
        case R.id.btn_about: {
        Intent activity = new Intent(FistActivity.this, About.class);
        startActivity(activity);
        break;
        }

    }
}}

}

另一种方式：

private static class PopupWindow extends PopupWindowActivity implements OnClickListener {
        public PopupWindow(View anchor) {
        super(anchor);
    }

    @Override
    protected void onCreate() {
        // inflate layout
        LayoutInflater inflater =
                (LayoutInflater) this.anchor.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);

        ViewGroup root = (ViewGroup) inflater.inflate(R.layout.popup, null);

        // setup button events
        ImageView searchButton = (ImageView) findViewById(R.id.btn_about);
        algebraButton.setOnClickListener(this);


        this.setContentView(root);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
        case R.id.btn_about: {
            Intent intent = new Intent();
            intent.setClass(this, About.class);

            startActivity(intent);
            break;
        }

        default:
            break;
        }
}}

eclipse说起初我应该从static删除private static class PopupWindow extends PopupWindowActivity implements，然后我跟随intent.setClass(this, About.class);：

The method setClass(Context, Class<?>) in the type Intent is not applicable for the arguments (FirstActivity.PopupWindow, Class<About>)

请帮助。

为第一次崩溃添加了日志：

03-07 00:28:07.750: D/AndroidRuntime(12472): Shutting down VM
03-07 00:28:07.750: W/dalvikvm(12472): threadid=1: thread exiting with uncaught exception (group=0x40018578)
03-07 00:28:07.759: E/AndroidRuntime(12472): FATAL EXCEPTION: main
03-07 00:28:07.759: E/AndroidRuntime(12472): java.lang.NullPointerException
03-07 00:28:07.759: E/AndroidRuntime(12472):    at com.example.FirstActivity$PopupWindow.onCreate(FirstActivity.java:110)
03-07 00:28:07.759: E/AndroidRuntime(12472):    at com.quickaction.PopupWindowActivity.<init>(PopupWindowActivity.java:52)
03-07 00:28:07.759: E/AndroidRuntime(12472):    at com.example.FirstActivity$PopupWindow.<init>(FirstActivity.java:97)
03-07 00:28:07.759: E/AndroidRuntime(12472):    at com.example.FirstActivity$1.onClick(FirstActivity.java:30)
03-07 00:28:07.759: E/AndroidRuntime(12472):    at android.view.View.performClick(View.java:2485)
03-07 00:28:07.759: E/AndroidRuntime(12472):    at android.view.View$PerformClick.run(View.java:9080)
03-07 00:28:07.759: E/AndroidRuntime(12472):    at android.os.Handler.handleCallback(Handler.java:587)
03-07 00:28:07.759: E/AndroidRuntime(12472):    at android.os.Handler.dispatchMessage(Handler.java:92)
03-07 00:28:07.759: E/AndroidRuntime(12472):    at android.os.Looper.loop(Looper.java:130)
03-07 00:28:07.759: E/AndroidRuntime(12472):    at android.app.ActivityThread.main(ActivityThread.java:3687)
03-07 00:28:07.759: E/AndroidRuntime(12472):    at java.lang.reflect.Method.invokeNative(Native Method)
03-07 00:28:07.759: E/AndroidRuntime(12472):    at java.lang.reflect.Method.invoke(Method.java:507)
03-07 00:28:07.759: E/AndroidRuntime(12472):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
03-07 00:28:07.759: E/AndroidRuntime(12472):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625)
03-07 00:28:07.759: E/AndroidRuntime(12472):    at dalvik.system.NativeStart.main(Native Method)

Answer 1

按下按钮：

Intent intent = new Intent("<your-intent-goes-here");
<context>.startActivity(intent);

Answer 2

有很多方法可以解决这个问题。一种方法是通过Dialog的构造函数传递对Context的引用。

如何从弹出窗口启动活动？

2 个答案: