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我正在尝试开始学习编写 Android 应用程序的技巧，因此我正在关注 Android 开发人员教程。我目前正在研究“开始另一个活动”部分，并且完全按照示例进行操作，但应用程序名称除外。当我为单击按钮时要调用的第二个活动添加类代码时，出现以下错误：缺少包语句：'com.VRCoreSoftware.testapp4'

所有相关的代码（据我所知）如下所示：

Main Activity.java：这里显示的唯一错误是它无法识别 DisplayMessageActivity.class Intent intent = new Intent(this, DisplayMessageActivity.class);

package com.VRCoreSoftware.testapp4;

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.os.Build;
// import android.view.View;
import android.content.Intent;
import android.widget.EditText;

public class MainActivity extends ActionBarActivity {

public final static String EXTRA_MESSAGE = "com.VRCoreSoftware.testapp4.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.
    switch (item.getItemId()) {
        case 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;
    }
}

public void sendMessage(View view) {
    // Do something in response to button
    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);
}

}

DisplayMessageActivity.java 有很多错误，源（我假设）是明显的失败导入。

import com.VRCoreSoftware.testapp4.MainActivity;

public class DisplayMessageActivity extends MainActivity {

@SuppressLint("NewApi")
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_display_message);

    // Make sure we're running on Honeycomb or higher to use ActionBar APIs
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
        // Show the Up button in the action bar.
        getActionBar().setDisplayHomeAsUpEnabled(true);
    }

    Intent intent = getIntent();
    String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);

     // Create the text view
     TextView textView = new TextView(this);
     textView.setTextSize(40);
    textView.setText(message);

    // Set the text view as the activity layout
    setContentView(textView);
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
    case android.R.id.home:
        NavUtils.navigateUpFromSameTask(this);
        return true;
    }
    return super.onOptionsItemSelected(item);
}
}

来自 AndroidManifest.xml 文件：这里唯一的错误是它无法识别行中的“DisplayMessageActivity”：android:name="com.VRCoreSoftware.testapp4.DisplayMessageActivity"

    <activity
        android:name="com.VRCoreSoftware.testapp4.DisplayMessageActivity"
        android:label="@string/title_activity_display_message"
        android:parentActivityName="com.VRCoreSoftware.testapp4.MainActivity" >
        <meta-data
            android:name="android.support.PARENT_ACTIVITY"
            android:value="com.VRCoreSoftware.testapp4.MainActivity" />
    </activity>

我目前正在使用 Android Studio 编写和编译这段代码。对于此事，我将不胜感激。非常感谢。

4

1 回答 1

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似乎 DisplayMessageActivity 与 MainActivity 不在同一个包中，这也意味着它不在 中com.VRCoreSoftware.testapp4，导致清单错误。将其移至正确的包装中，您就可以开始使用了。

于 2013-11-03T08:16:17.663 回答