第一课android

Question

当我开始在android设备中应用时，单击inly按钮后应用程序崩溃，这意味着进行下一个活动的意图不起作用，但是我不知道我的错误在哪里，我确定拼错了什么，但是在哪里？

06-06 21:00:13.692: E/AndroidRuntime(18154): FATAL EXCEPTION: main
06-06 21:00:13.692: E/AndroidRuntime(18154): Process: com.example.myfirstapp, PID:     18154
06-06 21:00:13.692: E/AndroidRuntime(18154): java.lang.RuntimeException: Unable to     start activity     ComponentInfo{com.example.myfirstapp/com.example.myfirstapp.DisplayMessageActivity}:     java.lang.IllegalArgumentException: No view found for id 0x7f05003c (com.example.myfirstapp:id/container) for fragment PlaceholderFragment{41ad8eb0 #0 id=0x7f05003c}
06-06 21:00:13.692: E/AndroidRuntime(18154):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2215)
06-06 21:00:13.692: E/AndroidRuntime(18154):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2265)
06-06 21:00:13.692: E/AndroidRuntime(18154):    at android.app.ActivityThread.access$800(ActivityThread.java:145)
06-06 21:00:13.692: E/AndroidRuntime(18154):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1206)
06-06 21:00:13.692: E/AndroidRuntime(18154):    at android.os.Handler.dispatchMessage(Handler.java:102)
06-06 21:00:13.692: E/AndroidRuntime(18154):    at android.os.Looper.loop(Looper.java:136)
06-06 21:00:13.692: E/AndroidRuntime(18154):    at android.app.ActivityThread.main(ActivityThread.java:5081)
06-06 21:00:13.692: E/AndroidRuntime(18154):    at java.lang.reflect.Method.invokeNative(Native Method)
06-06 21:00:13.692: E/AndroidRuntime(18154):    at java.lang.reflect.Method.invoke(Method.java:515)
06-06 21:00:13.692: E/AndroidRuntime(18154):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:781)
06-06 21:00:13.692: E/AndroidRuntime(18154):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
06-06 21:00:13.692: E/AndroidRuntime(18154):    at dalvik.system.NativeStart.main(Native Method)
06-06 21:00:13.692: E/AndroidRuntime(18154): Caused by: java.lang.IllegalArgumentException: No view found for id 0x7f05003c (com.example.myfirstapp:id/container) for fragment PlaceholderFragment{41ad8eb0 #0 id=0x7f05003c}
06-06 21:00:13.692: E/AndroidRuntime(18154):    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:930)
06-06 21:00:13.692: E/AndroidRuntime(18154):    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1115)
06-06 21:00:13.692: E/AndroidRuntime(18154):    at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682)
06-06 21:00:13.692: E/AndroidRuntime(18154):    at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1478)
06-06 21:00:13.692: E/AndroidRuntime(18154):    at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:570)
06-06 21:00:13.692: E/AndroidRuntime(18154):    at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1171)
06-06 21:00:13.692: E/AndroidRuntime(18154):    at android.app.Activity.performStart(Activity.java:5241)
06-06 21:00:13.692: E/AndroidRuntime(18154):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2178)
06-06 21:00:13.692: E/AndroidRuntime(18154):    ... 11 more
06-06 21:00:16.125: I/Process(18154): Sending signal. PID: 18154 SIG: 9

这是MainActivity，我认为这是错误，但我不知道在哪里：

package com.example.myfirstapp;

import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
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.EditText;
import android.os.Build;
import android.content.Intent;
import android.widget.EditText;

public class MainActivity extends ActionBarActivity {
    public final static String EXTRA_MESSAGE = "com.example.myfirstapp.MESSAGE";

    @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();
        }
    }


    @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 void sendMessage (View view){
    Intent intent = new Intent(this, DisplayMessageActivity.class);
    EditText editText = (EditText) findViewById(R.id.edit_message);
    String message = editText.getText().toString();
    intent.putExtra(EXTRA_MESSAGE, message);
    startActivity(intent);
}

/**
 * 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;
    }
}

}

清单中是否有有用的东西：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.myfirstapp"
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.example.myfirstapp.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>
    <activity
        android:name="com.example.myfirstapp.DisplayMessageActivity"
        android:label="@string/title_activity_display_message"
        android:parentActivityName="com.example.myfirstapp.MainActivity" >
        <meta-data
            android:name="android.support.PARENT_ACTIVITY"
            android:value="com.example.myfirstapp.MainActivity" />
    </activity>
</application>

</manifest>

Answer 1

尝试更改此行，然后检查它是否有效。

setContentView(R.layout.activity_main);

同

setContentView(com.example.myfirstapp.R.layout.activity_main);

因为android包中有R.java，并且如果您不小心导入了它，将会创建错误。

检查这是否是原因，如果不是，那么我们可以进一步诊断。

编辑： java.lang.IllegalArgumentException: No view found for id 0x7f05003c (com.example.myfirstapp:id/container) for fragment PlaceholderFragment{41ad8eb0 #0 id=0x7f05003c}

此行指示PlaceholderFragment中的问题。 所以问题可能出在这段代码中

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

在这里，您尝试将PlaceholderFragment添加到R.id.container 。