如何从快速动作启动活动？

Question

使用此项目 ，我的应用程序中有一个自定义弹出窗口（快速操作）。 我想单击按钮（在此弹出窗口中）后开始活动。 这是带有弹出窗口的活动代码：

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);
    popupButton.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;
        }

    }
}}

但是这种从弹出窗口启动活动的方法不起作用。 这是代码的另一个版本（源PopupWindow中是私有静态类）：

私有静态类PopupWindow扩展PopupWindowActivity实现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 intent = new Intent();
        intent.setClass(this, About.class);

        startActivity(intent);
        break;
    }

    default:
        break;
    }
}}

日食说，起初我应该删除从静态的 private static class PopupWindow extends PopupWindowActivity implements... ，然后我有以下的intent.setClass(this, About.class); ：

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

请帮助解决此问题。

---

添加了日志。 当我按下按钮打开弹出窗口时，应用会强制关闭并显示以下日志：

03-09 21:37:18.259: D/AndroidRuntime(9037): Shutting down VM
03-09 21:37:18.259: W/dalvikvm(9037): threadid=1: thread exiting with uncaught exception (group=0x40018578)
03-09 21:37:18.259: E/AndroidRuntime(9037): FATAL EXCEPTION: main
03-09 21:37:18.259: E/AndroidRuntime(9037): java.lang.NullPointerException
03-09 21:37:18.259: E/AndroidRuntime(9037):     at com.example.FirstActivity$PopupWindow.onCreate(FirstActivity.java:118)
03-09 21:37:18.259: E/AndroidRuntime(9037):     at com.example.PopupWindowActivity.<init>(PopupWindowActivity.java:52)
03-09 21:37:18.259: E/AndroidRuntime(9037):     at com.example.FirstActivity$PopupWindow.<init>(FirstActivity.java:103)
03-09 21:37:18.259: E/AndroidRuntime(9037):     at com.example.FirstActivity$1.onClick(FirstActivity.java:32)
03-09 21:37:18.259: E/AndroidRuntime(9037):     at android.view.View.performClick(View.java:2485)
03-09 21:37:18.259: E/AndroidRuntime(9037):     at android.view.View$PerformClick.run(View.java:9080)
03-09 21:37:18.259: E/AndroidRuntime(9037):     at android.os.Handler.handleCallback(Handler.java:587)
03-09 21:37:18.259: E/AndroidRuntime(9037):     at android.os.Handler.dispatchMessage(Handler.java:92)
03-09 21:37:18.259: E/AndroidRuntime(9037):     at android.os.Looper.loop(Looper.java:130)
03-09 21:37:18.259: E/AndroidRuntime(9037):     at android.app.ActivityThread.main(ActivityThread.java:3687)
03-09 21:37:18.259: E/AndroidRuntime(9037):     at java.lang.reflect.Method.invokeNative(Native Method)
03-09 21:37:18.259: E/AndroidRuntime(9037):     at java.lang.reflect.Method.invoke(Method.java:507)
03-09 21:37:18.259: E/AndroidRuntime(9037):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
03-09 21:37:18.259: E/AndroidRuntime(9037):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625)
03-09 21:37:18.259: E/AndroidRuntime(9037):     at dalvik.system.NativeStart.main(Native Method)

Answer 1

您可能需要将上下文传递到您的意图中。 通过创建一个接受Context作为参数之一的构造函数，尝试将上下文传递到popupwindowactivity中

例如

private static class PopupWindow extends PopupWindowActivity implements OnClickListener { 
    private Context context; //you now have access to context!

    public PopupWindow(View anchor, Context context) { //new constructor
    super(anchor); 
    this.context = context; //notice this!

    }

@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(context, About.class); //using the context down here!!

        startActivity(intent);
        break;
    }

    default:
        break;
    }
}}

注意代码intent.setClass（context，About.class）; 它利用了您传入的上下文