java - Android，接受用户的值并在下一个 Activity 中显示它们

Question

我应该询问用户姓名、年龄、电子邮件和电话号码，并在另一个 Activity 中显示这些值。 Android 开发培训(来自谷歌)中显示的示例对一个变量(键值对)做了同样的事情。但是，这里我必须传递 4 个值。在查找如何执行此操作时，我遇到了 Bundle。使用相同的方法，第二个 Activity 不显示任何内容，即 Activity 显示空白屏幕，尽管有 4 个 textView 对象。我的代码如下:

MainActivity.java

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;

public class MainActivity extends AppCompatActivity {

public static final String EXTRA_MESSAGE_NAME="com.example.myfirstapp.MESSAGE";
public static final String EXTRA_MESSAGE_AGE="com.example.myfirstapp.MESSAGE";
public static final String EXTRA_MESSAGE_EMAIL="com.example.myfirstapp.MESSAGE";
public static final String EXTRA_MESSAGE_PH="com.example.myfirstapp.MESSAGE";
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
}
public void sendMessage(View view) {
    Bundle extras=new Bundle();
    Intent intent = new Intent(this, DisplayMessageActivity.class);
    EditText editText = (EditText) findViewById(R.id.editText);
    String message = editText.getText().toString();
    extras.putString(EXTRA_MESSAGE_NAME, message);
    EditText editText2 = (EditText) findViewById(R.id.editText7);
    message=editText2.getText().toString();
    extras.putString(EXTRA_MESSAGE_AGE, message);
    EditText editText3 = (EditText) findViewById(R.id.editText5);
    message=editText3.getText().toString();
    extras.putString(EXTRA_MESSAGE_EMAIL, message);
    EditText editText4=(EditText)findViewById(R.id.editText6);
    message=editText4.getText().toString();
    extras.putString(EXTRA_MESSAGE_PH, message);
    intent.putExtras(extras);
    startActivity(intent);
}
}

第二个 Activity ，DisplayMessageActivity:

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;

import org.w3c.dom.Text;

public class DisplayMessageActivity extends AppCompatActivity {

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

    Intent intent=getIntent();
    Bundle extras=intent.getExtras();
    String message=extras.getString("EXTRA_MESSAGE_NAME");
    String message1=extras.getString("EXTRA_MESSAGE_AGE");
    String message2=extras.getString("EXTRA_MESSAGE_EMAIL");
    String message3=extras.getString("EXTRA_MESSAGE_PH");

    TextView textView= (TextView)findViewById(R.id.textView);
    textView.setText(message);

    TextView textView2=(TextView)findViewById(R.id.textView2);
    textView2.setText(message1);
    TextView textView3=(TextView)findViewById(R.id.textView3);
    textView3.setText(message2);
    TextView textView4=(TextView)findViewById(R.id.textView4);
    textView4.setText(message3);
}
}

activity_main.xml:

<EditText
    android:id="@+id/editText"
    android:layout_width="270dp"
    android:layout_height="wrap_content"
    android:layout_marginLeft="16dp"
    android:layout_marginRight="16dp"
    android:layout_marginTop="16dp"
    android:hint="@string/edit_name"
    android:inputType="textPersonName"
    app:layout_constraintHorizontal_bias="0.5"
    app:layout_constraintHorizontal_chainStyle="spread"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toTopOf="parent" />

<Button
    android:id="@+id/button"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:onClick="sendMessage"
    android:text="@string/button_send"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    android:layout_marginTop="16dp"
    app:layout_constraintTop_toBottomOf="@+id/editText6"
    app:layout_constraintHorizontal_bias="0.501" />

<EditText
    android:id="@+id/editText5"
    android:layout_width="270dp"
    android:layout_height="wrap_content"
    android:layout_marginLeft="16dp"
    android:layout_marginRight="16dp"
    android:layout_marginTop="16dp"
    android:ems="10"
    android:hint="@string/edit_email"
    android:inputType="textEmailAddress"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/editText7" />

<EditText
    android:id="@+id/editText6"
    android:layout_width="270dp"
    android:layout_height="wrap_content"
    android:layout_marginLeft="16dp"
    android:layout_marginRight="16dp"
    android:layout_marginTop="16dp"
    android:ems="10"
    android:hint="@string/edit_ph"
    android:inputType="phone"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/editText5" />

<EditText
    android:id="@+id/editText7"
    android:layout_width="270dp"
    android:layout_height="wrap_content"
    android:layout_marginLeft="16dp"
    android:layout_marginRight="16dp"
    android:layout_marginTop="16dp"
    android:ems="10"
    android:hint="@string/edit_age"
    android:inputType="number"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/editText" />
</android.support.constraint.ConstraintLayout>

activity_display_message.xml:

<TextView
    android:id="@+id/textView"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginLeft="16dp"
    android:layout_marginRight="16dp"
    android:layout_marginTop="16dp"
    android:text="TextView"
    android:textColor="@android:color/background_dark"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toTopOf="parent" />

<TextView
android:id="@+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="TextView"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
android:layout_marginTop="16dp"
app:layout_constraintTop_toBottomOf="@+id/textView" />

<TextView
    android:id="@+id/textView3"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="TextView"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    android:layout_marginTop="16dp"
    app:layout_constraintTop_toBottomOf="@+id/textView2" />

<TextView
    android:id="@+id/textView4"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="TextView"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    android:layout_marginTop="16dp"
    app:layout_constraintTop_toBottomOf="@+id/textView3" />
</android.support.constraint.ConstraintLayout>

如有任何帮助，我们将不胜感激。我是 Android 编程的新手，如果我犯了愚蠢的错误，请原谅，请随时指出。谢谢:)

Answer 1

您在第二个 Activity 中传递了错误的键，这就是为什么您的 Activity 在 Oncreate() 中崩溃的原因。

public static final String EXTRA_MESSAGE_NAME="com.example.myfirstapp.MESSAGE";
public static final String EXTRA_MESSAGE_AGE="com.example.myfirstapp.MESSAGE";
public static final String EXTRA_MESSAGE_EMAIL="com.example.myfirstapp.MESSAGE";
public static final String EXTRA_MESSAGE_PH="com.example.myfirstapp.MESSAGE";

上面你已经为 bundle 声明了键，但是在第二个 Activity 中你犯了错误。

  Intent intent=getIntent();
    Bundle extras=intent.getExtras();
    String message=extras.getString("EXTRA_MESSAGE_NAME");
    String message1=extras.getString("EXTRA_MESSAGE_AGE");
    String message2=extras.getString("EXTRA_MESSAGE_EMAIL");
    String message3=extras.getString("EXTRA_MESSAGE_PH");

你需要像下面这样传递 key :

 String message=extras.getString(MainActivity.EXTRA_MESSAGE_NAME);