Question

我试图通过"Start Another Activity"教程，但是，经过整个事情（两次），应用程序仍然拒绝返回在文本框中输入的文本 - 它总是返回＆＃34 ; Hello World＆＃34;。

我试图弄明白，并怀疑它可能与fragment_display_message.xml有关，其中EditText调用Hello World字符串。但我真的不知道。

任何帮助将不胜感激。这是代码：

MainActivity.java

package com.knargle.streetiteatit;

import android.content.Intent;
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.EditText;

public class MainActivity extends ActionBarActivity {

public final static String EXTRA_MESSAGE = "com.knargle.streetiteatit.MESSAGE";

    /** Called when the user clicks the Send button */
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);
}

@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);
}

/**
 * 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;
    }
}

}

fragment_main.xml

<LinearLayout 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:orientation="horizontal"
    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.knargle.streetiteatit.MainActivity$PlaceholderFragment" >

<EditText android:id="@+id/edit_message"
    android:layout_weight="1"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:hint="@string/edit_message" />

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/button_send"
    android:onClick="sendMessage" />

</LinearLayout>

DisplayMessageActivity.java

package com.knargle.streetiteatit;

import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.app.ActionBarActivity;
import android.view.LayoutInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

public class DisplayMessageActivity extends ActionBarActivity {

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

    // 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);

    setContentView(R.layout.activity_display_message);

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

    }
}

@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_display_message,
                container, false);
        return rootView;
    }
}

}

fragment_display_message.xml

<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.knargle.streetiteatit.DisplayMessageActivity$PlaceholderFragment" >

 <EditText android:id="@+id/edit_message"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:hint="@string/hello_world" />
</RelativeLayout>

Answer 1

setContentView中DisplayMessageActivity被调用两次。删除第二个：

setContentView(R.layout.activity_display_message);

Answer 2

在DisplayMessageActivity：

中

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

setContentView(R.layout.activity_display_message);

你拨打setContentView两次，这只会覆盖已经存在的内容。删除第二个setContentView。

Answer 3

从DisplayMessageActivity：

中删除这些行

// 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);

您试图在新的文本视图中设置消息，该视图不是布局文件的一部分。然后将该文本视图设置为布局的ContentView。这似乎是一种令人费解的方法。而是尝试以下方法：

在setContentView(R.layout.activity_display_message);行之后，添加以下行：

EditText editText = (EditText) findViewById(R.id.edit_message);
editText.setText(message);

这样，您可以使用布局文件中的现有Edit文本元素来显示消息。您的原始代码从未在此元素中替换HelloWorld。这就是为什么它总是向你展示HelloWorld而不是你的消息。

Answer 4

在DisplayMessageActivity.java文件中，您正在调用setContentView两次，因为它会覆盖第一行代码。目前您的代码如下所示：

setContentView(textView);
setContentView(R.layout.activity_display_message); // Delete this line. As this line of code appears in your java file, it is overwriting the 'text' you entered with the default 'hello world' message

应该是这样的：

setContentView(textView);

Answer 5

您可以按照Andrew和Rajesh的回答。但事实上你已经定义了一个布局fragment_display_message，我相信你想要使用它。在这种情况下，您需要做的就是摆脱代码以动态添加TextView和相应的setContentView，并保留第二个使用您的布局的setContentView。完成后，您将获得对EditText的引用，并将其文本设置为Intent中发送的内容。

返回在文本框中输入的文本

5 个答案: