Question

我一直有这个问题，这是我的第一个Android应用程序，我可能做了一些愚蠢的事情。我是一个完全的菜鸟，这让我疯了。运行应用程序会给我一个错误，“不幸的是 - 应用程序已停止工作。”帮助将不胜感激

Fragment Main：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.gmail.sherwoodax.appone.MainActivity$PlaceholderFragment" >

    <Button
        android:id="@+id/dBID"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Dead Button" 
        android:layout_centerInParent="true"

        />

    <TextView
        android:id="@+id/tView"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="The Button is below me"
        android:layout_above="@+id/dBID"
        android:gravity="center"
        android:textSize="20sp"

        />

</RelativeLayout>

主类：

package com.gmail.sherwoodax.appone;



import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.app.ActionBarActivity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends ActionBarActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        if (savedInstanceState == null) {
            getSupportFragmentManager().beginTransaction()
                    .add(R.id.container, new PlaceholderFragment())
                    .commit();

            testMethod();
        }



    }


    private void testMethod() {

        Button b = (Button) findViewById(R.id.dBID);

        b.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub

                Toast.makeText(MainActivity.this, "text", Toast.LENGTH_LONG).show();

            }
        });

    }


    @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);
    }

    /**
     * A placeholder fragment containing a simple view.
     */
    public static class PlaceholderFragment extends Fragment {

        public PlaceholderFragment() {
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
            View rootView = inflater.inflate(R.layout.fragment_main, container, false);
            return rootView;
        }
    }

}

清单：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.gmail.sherwoodax.appone"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="19" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.gmail.sherwoodax.appone.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

LogCat stacktrace：

05-28 11:15:54.977: E/AndroidRuntime(31586): Caused by: java.lang.IllegalArgumentException: No view found for id 0x7f05003c (com.gmail.sherwoodax.appone:id/container) for fragment PlaceholderFragment{41c157b0 #0 id=0x7f05003c}
05-28 11:20:47.344: E/AndroidRuntime(32409): Caused by: java.lang.IllegalArgumentException: No view found for id 0x7f05003c (com.gmail.sherwoodax.appone:id/container) for fragment PlaceholderFragment{41c10d00 #0 id=0x7f05003c}

谢谢

Answer 1

请发布崩溃的logcat堆栈跟踪，以便我们帮助查明确切的问题。但是，我猜它与你的Button有关。

在testMethod()声明：

Button b = (Button) findViewById(R.id.dBID);

但是因为它是在这个方法中声明的，所以它不在你的活动范围内，只存在于单个方法调用中，之后就会丢失。

您应该在Activity / Fragment中将您的按钮声明为类级别变量：

public class MainActivity extends ActionBarActivity {
    private Button myButton;
    ...

然后在onCreate()（或片段onViewCreate()）中指定按钮：

public void onCreate(...) {
    myButton = (Button) findViewById(...);
    ...

然后在你班级的任何其他地方，你想要使用那个按钮，你可以参考它而无需从你的视图中再次拉出它：

button.setText(newButtonText);

＆＃34;不幸的是 - 已停止＃34;在我的第一个Android应用程序上

1 个答案: