Java 为什么我不'；无法从其他活动中获取字符串？

您好，我想构建一个android应用程序，向其他活动发送文本，但在第二个活动中我看不到输入文本：（我尝试了本教程：

            Bundle bundle = getIntent().getExtras();
            if(bundle != null)
            {
                String message = bundle.getString(MainActivity.EXTRA_MESSAGE);
            }

            Bundle bundle = getIntent().getExtras();
            if(bundle != null)
            {
                String message = bundle.getString(MainActivity.EXTRA_MESSAGE);
            }

在本教程中，我也会这样做：

            Bundle bundle = getIntent().getExtras();
            if(bundle != null)
            {
                String message = bundle.getString(MainActivity.EXTRA_MESSAGE);
            }

如果我点击send，我将使用Intent类并输出我的字符串

            Bundle bundle = getIntent().getExtras();
            if(bundle != null)
            {
                String message = bundle.getString(MainActivity.EXTRA_MESSAGE);
            }

这是我的DisplayMessageActivity.java代码

public class DisplayMessageActivity extends ActionBarActivity {

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

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

                // Get the message from the intent
                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);


    }

    /**
     * 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;
        }
    }
}

            Bundle bundle = getIntent().getExtras();
            if(bundle != null)
            {
                String message = bundle.getString(MainActivity.EXTRA_MESSAGE);
            }

更新：

            Bundle bundle = getIntent().getExtras();
            if(bundle != null)
            {
                String message = bundle.getString(MainActivity.EXTRA_MESSAGE);
            }

我的第一项活动：

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);
    }

    // Button Events

    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);
    }
}

            Bundle bundle = getIntent().getExtras();
            if(bundle != null)
            {
                String message = bundle.getString(MainActivity.EXTRA_MESSAGE);
            }

---

尝试在DisplayMessageActivity中获取您的包

            Bundle bundle = getIntent().getExtras();
            if(bundle != null)
            {
                String message = bundle.getString(MainActivity.EXTRA_MESSAGE);
            }

在《发件人法》中：

            Bundle bundle = getIntent().getExtras();
            if(bundle != null)
            {
                String message = bundle.getString(MainActivity.EXTRA_MESSAGE);
            }

                    Intent intent = new Intent(Activity_A.this, DisplayMessageActivity.class);
                    intent.putExtra(MainActivity.EXTRA_MESSAGE, "Your title");

                    Activity_A.this.startActivity(intent);

---

MainActivity.EXTRA_MESSAGE是您的密钥传递

使用密钥传递来自第一个活动的消息，并在第二个活动中获取这些值，如下所示

            Bundle bundle = getIntent().getExtras();
            if(bundle != null)
            {
                String message = bundle.getString(MainActivity.EXTRA_MESSAGE);
            }

    bundle = getIntent().getExtras();
    if (bundle != null) {
       value1 = bundle.getString("key1");
        value2 = bundle.getString("key2");
    }

 intent.putExtra("key1", "message1");
 intent.putExtra("key2", "message2");

在第一个活动中，像这样传递消息

            Bundle bundle = getIntent().getExtras();
            if(bundle != null)
            {
                String message = bundle.getString(MainActivity.EXTRA_MESSAGE);
            }

    bundle = getIntent().getExtras();
    if (bundle != null) {
       value1 = bundle.getString("key1");
        value2 = bundle.getString("key2");
    }

 intent.putExtra("key1", "message1");
 intent.putExtra("key2", "message2");

试一试

            Bundle bundle = getIntent().getExtras();
            if(bundle != null)
            {
                String message = bundle.getString(MainActivity.EXTRA_MESSAGE);
            }

在第一个活动中

            Bundle bundle = getIntent().getExtras();
            if(bundle != null)
            {
                String message = bundle.getString(MainActivity.EXTRA_MESSAGE);
            }

intent.putExtra("EXTRA_MESSAGE", "Your title");

---

我在你的代码中没有看到2个活动。这是第二个…我也发布了第一个…时刻发布你的MainActivity代码。因为当你正确地传入MainActivity并启动当前活动（DisplayMessageActivity）时，它会出现为什么不出现？你能在DisplayMessageActivity中获得你的包吗？