android - 我创建了一个包含两个 Activity 的 Android 应用程序，但无法从第二个 Activity 切换回第一个

Question

我创建了一个包含两个 Activity 的 Android 应用程序，但是第二个 Activity 上的按钮似乎无法正常工作。第一个 Activity 上的按钮(一个 map Activity 和一个添加信息的按钮，它将用户带到带有信息输入屏幕的第二个 Activity )工作正常，第二个 Activity 上的按钮似乎没有任何效果......我不能甚至让 OnClick Toast 消息起作用。

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback , LocationListener {

   public void AddMapInfo(View view) {

    Intent intent = new Intent(this, InformationInputActivity.class);
    LatLng providedLocation = current;
    Bundle args = new Bundle();
    args.putParcelable("provided_location", providedLocation);
    intent.putExtra("bundle", args);
    startActivityForResult(intent, 1);
}

public void onActivityResult (int requestCode, int resultCode, Intent data){
    Toast.makeText(this, "back with cheese!", Toast.LENGTH_LONG).show();

    if (requestCode != 1){

        Toast.makeText(this, "Oops... This shouldn't happen", Toast.LENGTH_LONG).show();

    }
    else{

        setContentView(R.layout.activity_maps);
        InformationPoint informationPoint = (InformationPoint) data.getSerializableExtra("information_point");

        informationPoint.display(mymap);

    }

}


}

第二个 Activity 带来了屏幕布局，它为 EditText 字段设置了正确的选项，所以我知道它获得了控制……但仅此而已。没有来自任何方法的 toast 消息(当在第一个 Activity 中收到位置更新信息时我仍然得到 toast )，单选按钮或提交按钮似乎都不起作用，我也没有得到结果并控制回到第一个 Activity 。 (以前，我曾经能够在单选按钮上的选中选项上获得 Toast on ever，但现在这似乎也不起作用)。尝试发送 Activity 结果会中止应用程序(因为我将 finish() 添加到第二个 Activity )。

/* java */
package com.example.m.googlemapappfirst;

import android.content.Intent;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.RadioButton;
import android.widget.TextView;
import android.widget.Toast;

import com.google.android.gms.maps.model.LatLng;

import org.w3c.dom.Text;


public class InformationInputActivity extends ActionBarActivity {

EditText editText;
String content = "";
LatLng providedLocation;

public InfoType infoType = InfoType.NO_INFO;
InformationPoint informationPoint;

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

    Intent intent = getIntent();
    Bundle bundle = getIntent().getParcelableExtra("bundle");
    providedLocation = bundle.getParcelable("provided_location");
    String message = String.valueOf(providedLocation);

    editText = (EditText)findViewById(R.id.description);
    editText.setHorizontallyScrolling(false);
    editText.setMaxLines(5);


    Toast.makeText(this, "enter cheese info", Toast.LENGTH_LONG);

}

public void onRadioButtonClicked(View view) {
    // Is the button now checked?


    boolean checked = ((RadioButton) view).isChecked();


    Toast.makeText(this,"you selected your cheese", Toast.LENGTH_LONG);


}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_information_input, 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();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}


public void AddPictureHandler(View view){
    Toast.makeText(this, "i like to take pictures of cheese", Toast.LENGTH_LONG).show();
}

public void SubmitHandler(View view){
    content = editText.getText().toString();

    Toast.makeText(this, "add cheese info", Toast.LENGTH_LONG).show();

    if(infoType == InfoType.NO_INFO){

        Toast.makeText(this, "Please select an Information type", Toast.LENGTH_LONG).show();
    }
    else if(content.equals("")){

        Toast.makeText(this, "Please write a description", Toast.LENGTH_LONG).show();

    }

    informationPoint = new InformationPoint(providedLocation, infoType, content);

    Intent returnIntent = new Intent(this, MapsActivity.class);
    returnIntent.putExtra("information_point", informationPoint);

    this.setResult(1, returnIntent);
    finish(); /* added after original post, this makes app crash consistently */


}

}

这是第二个 Activity 的 xml 布局文件:

<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:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
android:orientation="vertical"
tools:context="com.example.m.googlemapappfirst.InformationInputActivity">

<TextView android:text="@string/instructions"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" />

<RadioGroup xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical">
    <RadioButton android:id="@+id/radio_swiss"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/swiss"
        android:onClick="onRadioButtonClicked"/>
    <RadioButton android:id="@+id/radio_american"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/american"
        android:onClick="onRadioButtonClicked"/>
    <RadioButton android:id="@+id/radio_gruyere"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/gruyere"
        android:onClick="onRadioButtonClicked"/>
    <RadioButton android:id="@+id/radio_cheddar"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/cheddar"
        android:onClick="onRadioButtonClicked"/>
</RadioGroup>

<TextView android:text="@string/instructions2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" />


<EditText
    android:id="@+id/description"
    android:layout_width="fill_parent"
    android:layout_height="60dp"
    android:layout_weight="1"
    android:hint="@string/type_here"
    android:inputType="text"
    android:imeOptions="actionDone"
    android:maxLines ="4"
    android:maxLength ="2000"
    android:scrollHorizontally="false"
    />


<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="wrap_content"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:orientation="horizontal">


    <Button
        android:id="@+id/take_picture_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Add Picture"
        android:onClick="AddPictureHandler" />

    <Button
        android:id="@+id/submit_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Report Information"
        android:onClick="SubmitHandler" />

</LinearLayout>

Answer 1

我没有看到任何问题，但在创建 toast 后缺少对 show() 的调用，就像这样:

    Toast.makeText(this, "Oops... This shouldn't happen", Toast.LENGTH_LONG).show();