Question

嗨，我是android新手，如果有人能够帮助我解决此问题，将不胜感激。现在我正在尝试回到上一个视图或根视图，有人知道如何从静态上下文返回到上一个视图（我不确定静态上下文是正确的表达方式，如果有的话可以随意纠正我）我错了）？

我已经尝试创建FragmentManager的原因是因为我要创建的应用程序使用了Fragment。

 FragmentManager fragmentManager = 
 ((FragmentActivity)mContext).getSupportFragmentManager();
            fragmentManager.popBackStack();

`

public class SomeView1 extends View implements View.OnTouchListener {


public SomeView1(Context c) {
    super(c);

    mContext = c;
    setFocusable(true);
    setFocusableInTouchMode(true);

    this.setOnTouchListener(this);

}

public SomeView1(Context context, AttributeSet attrs) {
    super(context, attrs);
    mContext = context;

}

public void foodPortionCal() {

    final AlertDialog.Builder builder = new AlertDialog.Builder(mContext);
    builder.setTitle("Output");
    builder.setMessage("Message here");

    builder.setCancelable(true);

    builder.setNegativeButton("Ok", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            sqLiteHelper.insertDataFood(GlobalVariable.mealTypeF, String.format("%.2f", totalProteinPer) + '%', String.format("%.2f", totalGrainsPer) + '%', String.format("%.2f", totalVegetablePer) + '%', String.format("%.2f", totalFruitPer) + '%', String.format("%.2f", totalDairyPer) + '%', GlobalVariable.dataF);
            Toast.makeText(mContext, "Added", Toast.LENGTH_SHORT).show();
            //this is where I want to set the feature to remove the view/static context?
            FragmentManager fragmentManager = ((FragmentActivity)mContext).getSupportFragmentManager();
            fragmentManager.popBackStack();


            dialog.dismiss();


        }
    });

    builder.show();


  }
}

//Before going the code will move to someview1 we will be in a fragment class called FoodFragment and this is how it look like

public class Food_Cal extends Fragment {

    private void mealTypeSelection()
    {
    //this is how I call the come view activity
            getActivity().setContentView(new SomeView1(view.getContext()));


    }

}

//这是此应用程序构建方式的链接Android: Free Cropping of Image 唯一最大的不同是，我的应用使用片段，而引用没有的代码

想要获得的结果是要么将其移动到带有片段的下一个视图，要么一直返回到带有片段的根视图。我得到的结果是应用程序继续崩溃并且无法返回到根视图，然后应用程序崩溃这是我得到的错误消息

2019-04-27 00:35:36.599 624-624/apd.bii.diabetesappv1 E/AndroidRuntime: FATAL EXCEPTION: main
Process: apd.bii.diabetesappv1, PID: 624
java.lang.ClassCastException: android.view.ContextThemeWrapper cannot be cast to android.support.v4.app.FragmentActivity
    at apd.bii.diabetesappv1.FoodCalculation.SomeView1$1.onClick(SomeView1.java:437)
    at com.android.internal.app.AlertController$ButtonHandler.handleMessage(AlertController.java:173)
    at android.os.Handler.dispatchMessage(Handler.java:106)
    at android.os.Looper.loop(Looper.java:164)
    at android.app.ActivityThread.main(ActivityThread.java:6894)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:857)

Answer 1

这是一种用于将片段添加到FragmentManger中以便使其可见的简单方法。您需要做的就是传递要添加到屏幕上的片段。

public void addScreen(Fragment fragment) {
    getSupportManager()
        .beginTransaction()
        .replace(R.id.container, fragment)
        .addToBackStack(null)
        .commit();
    screensOnTheStack++;
}

当您想将该片段从堆栈中弹出并转到父视图时，是

while (screensOnTheStack > 0) {
        fragments.popBackStackImmediate();
    }

或者只是通过定义片段TAG来确定root(parent) fragment，例如

private static final String BACK_STACK_ROOT_TAG = "root_fragment";

然后


    // Pop off everything up to and including the current tab
    FragmentManager fragmentManager = getSupportFragmentManager();
    fragmentManager.popBackStack(BACK_STACK_ROOT_TAG, FragmentManager.POP_BACK_STACK_INCLUSIVE);

    // Add the new tab fragment
    fragmentManager.beginTransaction()
        .replace(R.id.container, TabFragment.newInstance())
        .addToBackStack(BACK_STACK_ROOT_TAG)
        .commit();

现在，对于您所说的部分

想要获得的结果是要么将其移至带有片段的下一个视图，要么一直返回至具有片段的根视图。

您可以根据自己的条件来决定何时要转到想要的片段，或者转到父视图。

返回第一视图/根视图的内容

1 个答案: