Question

这是Logcat的代码请帮忙。当我点击每次运行这些错误时，即使我搜索了一些东西。

        10-03 16:27:07.114: D/AndroidRuntime(7652): Shutting down VM
10-03 16:27:07.114: W/dalvikvm(7652): threadid=1: thread exiting with uncaught exception (group=0x41271930)
10-03 16:27:07.114: E/AndroidRuntime(7652): FATAL EXCEPTION: main
10-03 16:27:07.114: E/AndroidRuntime(7652): java.lang.RuntimeException: Unable to start activity ComponentInfo{wagr.ftc.cascade_app/wagr.ftc.cascade_app.MainActivity}: java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first.

这是我的实际代码

package wagr.ftc.cascade_app;

import android.app.ActionBar;
import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.NumberPicker;



public class MainActivity extends Activity {

    private AutonomousFragment autoFrag;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        // set action bar
        ActionBar actionBar = getActionBar();
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
        actionBar.setDisplayShowHomeEnabled(false);
        actionBar.setDisplayShowTitleEnabled(false);

        autoFrag = new AutonomousFragment();

        FragmentManager fM = getFragmentManager();
        FragmentTransaction fT = fM.beginTransaction();
        fT.add(R.id.container,autoFrag );
        fT.commit();

//        //add tabs
//          actionBar.addTab(actionBar.newTab()
//                  .setText("General")
//                  .setTabListener(new CustomTabListener<AutonomousFragment>(autoFrag,this,AutonomousFragment.class)));
    }



    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }


    public static class AutonomousFragment extends Fragment{

        private NumberPicker rampPicker, ballsGoalPicker;

        @Override
        public void onCreate(Bundle savedInstanceState)
        {
            super.onCreate(savedInstanceState);
        }

        @Override
         public View onCreateView(LayoutInflater inflater, ViewGroup container,
                    Bundle savedInstanceState) {
            View v = inflater.inflate(R.layout.fragment_main, container);
            rampPicker = (NumberPicker) v.findViewById(R.id.Rolling_Goal_Number_Picker);
            ballsGoalPicker = (NumberPicker)v.findViewById(R.id.Ramp_Rolling_Goals_Number_Picker);

            rampPicker.setMaxValue(3);
            rampPicker.setMinValue(0);
            ballsGoalPicker.setMaxValue(2);
            ballsGoalPicker.setMinValue(0);

            return v;
        }
    }
}

任何人都可以告诉我为什么我的应用程序运行不正常？我是新手，需要帮助。

Answer 1

问题是你在这条线上夸大观点的方式：

View v = inflater.inflate(R.layout.fragment_main, container);

两种最常见的inflate()方法是inflate(int, ViewGroup)和inflate(int, ViewGroup, boolean)。第三个参数很重要 - 如果将其设置为true，那么您膨胀的布局将附加到作为第二个参数传递的ViewGroup。如果设置为false，则布局inflater将仅使用第二个参数为新布局提供一组LayoutParams。

如果您使用两个参数inflate()并传入非空ViewGroup，那么膨胀的视图会自动附加，就像您使用了三个参数inflate()并传递{ {1}}作为第三个参数。

这一点非常重要，因为当您的true返回视图时，Android会尝试将返回的视图作为片段的布局附加。但是，由于您使用了两个参数方法，因此您的膨胀布局已经附加到另一个父级。

将该行切换为以下内容，您应该没问题。

onCreateView()

Answer 2

我认为堆栈跟踪不完整，查看完整堆栈会很有用。

无论如何，虽然我实际上没有尝试过您的代码，但由于以下原因，您可能会遇到此错误：

View v = inflater.inflate(R.layout.fragment_main, container);

如果您导航到inflate实现，它看起来像：

/**
 * Inflate a new view hierarchy from the specified xml node. Throws
 * {@link InflateException} if there is an error. *
 * <p>
 * <em><strong>Important</strong></em>&nbsp;&nbsp;&nbsp;For performance
 * reasons, view inflation relies heavily on pre-processing of XML files
 * that is done at build time. Therefore, it is not currently possible to
 * use LayoutInflater with an XmlPullParser over a plain XML file at runtime.
 * 
 * @param parser XML dom node containing the description of the view
 *        hierarchy.
 * @param root Optional view to be the parent of the generated hierarchy.
 * @return The root View of the inflated hierarchy. If root was supplied,
 *         this is the root View; otherwise it is the root of the inflated
 *         XML file.
 */
public View inflate(XmlPullParser parser, ViewGroup root) {
    return inflate(parser, root, root != null);
}

因此，如果您将该行替换为下一行，则可能有效：

View v = inflater.inflate(R.layout.fragment_main, container, false);

指定的子项已有父项。你必须在孩子的父亲first1上调用removeView（）

2 个答案: