单击时电子邮件意图未启动

Question

我正在使用电子邮件意图是我的第二个活动，没有错误，但是当单击按钮时，电子邮件意图没有启动并返回到我的 java 应用程序。请帮帮我！

这是我的secondactivity.xml：

<?xml version="1.0" encoding="utf-8"?>
<ScrollView   xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".SecondActivity">


    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="1"
        android:background="@drawable/bg">

        <TextView
            android:id="@+id/header"
            android:text="MAKAN DAN MINUMAN"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textSize="25sp"
            android:textColor="@color/colorWhitebone"
            android:layout_centerHorizontal="true"/>

        <ImageView
            android:id="@+id/gado"
            android:layout_width="250dp"
            android:layout_height="250dp"
            android:src="@drawable/gado"
            android:layout_centerHorizontal="true"
            android:layout_below="@id/header">
        </ImageView>
        <TextView
            android:id="@+id/tgd"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Gado Gado"
            android:textColor="@color/colorWhitebone"
            android:textSize="25dp"
            android:layout_centerHorizontal="true"
            android:layout_below="@id/gado">

        </TextView>
        <ImageView
            android:id="@+id/ka"
            android:layout_width="250dp"
            android:layout_height="250dp"
            android:layout_below="@id/plus"
            android:layout_centerHorizontal="true"
            android:src="@drawable/ka">
        </ImageView>
        <TextView
            android:id="@+id/tka"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Kopi Aceh"
            android:textColor="@color/colorWhitebone"
            android:textSize="25dp"
            android:layout_centerHorizontal="true"
            android:layout_below="@id/ka">

        </TextView>

        <Button
            android:id="@+id/minus2"
            android:layout_width="48dp"
            android:layout_height="48dp"
            android:text="-"
            android:onClick="decrement2"
            android:layout_centerHorizontal="true"
            android:layout_below="@id/tka"/>

        <TextView
            android:id="@+id/quantity_text_view2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:paddingLeft="8dp"
            android:paddingRight="8dp"
            android:text="@string/initial_quantity_value"
            android:textColor="@android:color/white"
            android:textSize="16sp"
            android:layout_centerHorizontal="true"
            android:layout_below="@id/minus2"
            />


        <Button
            android:id="@+id/plus2"
            android:layout_width="48dp"
            android:layout_height="48dp"
            android:text="+"
            android:onClick="increment2"
            android:layout_centerHorizontal="true"
            android:layout_below="@id/quantity_text_view2"
            />

        <Button
            android:id="@+id/minus"
            android:layout_width="48dp"
            android:layout_height="48dp"
            android:text="-"
            android:onClick="decrement"
            android:layout_centerHorizontal="true"
            android:layout_below="@id/tgd"/>

        <TextView
            android:id="@+id/quantity_text_view"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:paddingLeft="8dp"
            android:paddingRight="8dp"
            android:text="@string/initial_quantity_value"
            android:textColor="@android:color/white"
            android:textSize="16sp"
            android:layout_centerHorizontal="true"
            android:layout_below="@id/minus"
           />


        <Button
            android:id="@+id/plus"
            android:layout_width="48dp"
            android:layout_height="48dp"
            android:text="+"
            android:onClick="increment"
            android:layout_centerHorizontal="true"
            android:layout_below="@id/quantity_text_view"
           />

        <Button
            android:id="@+id/order"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="16dp"
            android:layout_below="@id/gado"
            android:onClick="submitOrder"
            android:text="@string/order" />
    <Button
        android:id="@+id/btn_back"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Back"
        android:layout_alignParentBottom="true"
        />
    </RelativeLayout>
</ScrollView>

这是我的第二个 java

package com.example.moveintent;

    import androidx.appcompat.app.AppCompatActivity;

    import android.os.Bundle;

    import android.view.View;

    import android.widget.Button;

    import android.widget.TextView;


    import android.widget.CheckBox;

    import android.widget.EditText;

    import android.widget.Toast;

    import java.text.NumberFormat;

    import android.text.Editable;

    import android.content.Intent;
    import android.net.Uri;


    public class SecondActivity extends AppCompatActivity implements View.OnClickListener


{

    private Button btnBack;
    int quantity = 0;
    int quantity2 =0;

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

        btnBack = findViewById(R.id.btn_back);
        btnBack.setOnClickListener(this);

        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    }

    public void increment(View view){
        if (quantity == 100){
            //show an error message as a toast
            Toast.makeText(this,"You cannot have more than 100 foods/drinks", Toast.LENGTH_SHORT ).show();
            //exit this method early because nothing to do
            return;
        }
        quantity = quantity + 1;
        displayQuantity(quantity);
    }
    public void decrement(View view){
        if (quantity == 1){
            //show an error message as a toast
            Toast.makeText(this,"You cannot have less than 1 foor/drink", Toast.LENGTH_SHORT ).show();
            //exit this method early because nothing to do
            return;
        }
        quantity = quantity - 1;
        displayQuantity(quantity);
    }

    public void increment2(View view){
        if (quantity2 == 100){
            //show an error message as a toast
            Toast.makeText(this,"You cannot have more than 100 foods/drinks", Toast.LENGTH_SHORT ).show();
            //exit this method early because nothing to do
            return;
        }
        quantity2 = quantity2 + 1;
        displayQuantity2(quantity2);
    }
    public void decrement2(View view){
        if (quantity2 == 1){
            //show an error message as a toast
            Toast.makeText(this,"You cannot have less than 1 foor/drink", Toast.LENGTH_SHORT ).show();
            //exit this method early because nothing to do
            return;
        }
        quantity2 = quantity2 - 1;
        displayQuantity2(quantity2);
    }

    /**
     * This method is called when the order button is clicked.
     */
    public void submitOrder(View view) {
        // Get user's name
        EditText nameField = (EditText) findViewById(R.id.name_field);
        Editable nameEditable = nameField.getText();
        String name = nameEditable.toString();

        //get user's number
        EditText hpField = (EditText) findViewById(R.id.hp_field);
        Editable nomorEditable = hpField.getText();
        String nomor = nomorEditable.toString();

        // Figure out if the user wants pempek
        CheckBox pempekCheckBox = (CheckBox) findViewById(R.id.pempek_checkbox);
        boolean hasPempek = pempekCheckBox.isChecked();

        // Figure out if the user wants kue gandus
        CheckBox gandusCheckBox = (CheckBox) findViewById(R.id.gandus_checkbox);
        boolean hasGandus = gandusCheckBox.isChecked();

        // Figure out if the user wants bongkol
        CheckBox bongkolCheckBox = (CheckBox) findViewById(R.id.bongkol_checkbox);
        boolean hasBongkol = bongkolCheckBox.isChecked();

        // Figure out if the user wants risol
        CheckBox risolCheckBox = (CheckBox) findViewById(R.id.risol_checkbox);
        boolean hasRisol = risolCheckBox.isChecked();

        // Calculate the price
        int price = calculatePrice(hasPempek, hasGandus , hasBongkol , hasRisol);

        // Display the order summary on the screen
        String priceMessage = createOrderSummary(name, nomor, price, hasPempek, hasGandus , hasBongkol , hasRisol);

        // Use an intent to launch an email app.
        // Send the order summary in the email body.
        Intent intent = new Intent(Intent.ACTION_SENDTO);
        intent.setData(Uri.parse("mailto:")); // only email apps should handle this
        intent.putExtra(Intent.EXTRA_SUBJECT, "Just java order for " + name);
        intent.putExtra(Intent.EXTRA_TEXT,priceMessage );
        if (intent.resolveActivity(getPackageManager()) != null) {
            startActivity(intent);

        }
    }

    /**
     * Calculates the price of the order.
     *
     * @param addPempek is whether or not we should include pempek in the price
     * @param addGandus   is whether or not we should include gandus in the price
     * @param addBongkol   is whether or not we should include bongkol in the price
     * @param addRisol   is whether or not we should include risol in the price
     * @return total price
     */
    private int calculatePrice(boolean addPempek, boolean addGandus , boolean addBongkol , boolean addRisol) {
        // First calculate the price of one appetizer
        int basePrice = 5;

        // If the user wants pempek, add 10000
        if (addPempek) {
            basePrice = basePrice + 10000;
        }

        // If the user wants kue gandus, add 10000
        if (addGandus) {
            basePrice = basePrice + 10000;
        }

        // If the user wants bongkol, add 10000
        if (addBongkol) {
            basePrice = basePrice + 10000;
        }

        // If the user wants risol, add 10000
        if (addRisol) {
            basePrice = basePrice + 10000;
        }



        // Calculate the total order price by multiplying by the quantity
        return quantity + quantity2 * basePrice;
    }

    /**
     * Create summary of the order.
     *
     * @param name            on the order
     * @param price           of the order
     * @param addPempek is whether or not to add pempek
     * @param addGandus    is whether or not to add kue gandus
     * @param addBongkol    is whether or not to add bongkol
     * @param addRisol   is whether or not to add risol
     * @return text summary
     */
    private String createOrderSummary(String name,String nomor, int price,boolean addPempek, boolean addGandus , boolean    addBongkol , boolean addRisol) {
        String priceMessage = getString(R.string.order_summary_name, name);
        priceMessage  = getString(R.string.order_summary_nomor, nomor);
        priceMessage += "\n" + getString(R.string.order_summary_pempek, addPempek);
        priceMessage += "\n" + getString(R.string.order_summary_gandus, addGandus);
        priceMessage += "\n" + getString(R.string.order_summary_bongkol, addBongkol);
        priceMessage += "\n" + getString(R.string.order_summary_risol, addRisol);
        priceMessage += "\n" + getString(R.string.order_summary_quantity, quantity);
        priceMessage += "\n" + getString(R.string.order_summary_quantity, quantity);
        priceMessage += "\n" + getString(R.string.order_summary_price,
                NumberFormat.getCurrencyInstance().format(price));
        priceMessage += "\n" + getString(R.string.thank_you);
        return priceMessage;
    }


    private void displayQuantity(int numberOfFoods) {
        TextView quantityTextView = (TextView) findViewById(
                R.id.quantity_text_view);
        quantityTextView.setText("" + numberOfFoods);
    }

    private void displayQuantity2(int numberOfFoods) {
        TextView quantityTextView2 = (TextView) findViewById(
                R.id.quantity_text_view2);
        quantityTextView2.setText("" + numberOfFoods);
    }


    @Override
    public boolean onSupportNavigateUp() {
        finish();
        return true;
    }

    @Override
    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.btn_back:
                finish();
                break;
        }
    }
}

Answer 1

请检查可能导致您问题的打击：

1. 在您提供的代码中，您没有触发submitOrder(View view)，其中包含发送电子邮件意图的代码；所以要确保当按钮被点击时，这个方法被触发。

2. 如果您的设备上没有可以处理此意图的活动组件，那么 android 系统会在不通知您的情况下保持您的应用程序运行 >>> 这通常发生在甚至没有 Gmail 应用程序的旧模拟器上安装。您可以在下面的代码 if 语句中使用 else 来验证这一点

   if (intent.resolveActivity(getPackageManager()) != null) {
       startActivity(intent);
   
   } else {
       Log.d("Log_TAG", "No activity on the device (email app) that can handle my intent");
   }
   

如果您需要进一步的帮助，请告诉我

Answer 2

谢谢赞恩！

if (intent.resolveActivity(getPackageManager()) != null) {
    startActivity(intent);

} else {
    Log.d("Log_TAG", "No activity on the device (email app) that can handle my intent");
}

代码完美运行！！