Android 通过“后退”按钮返回主活动时应用程序崩溃

我创建了“返回主页”活动的按钮，但当我按下此按钮时，不幸的是，它工作正常，我不明白为什么，但我希望此错误不会出现，并且 这是我的密码

家庭活动

package com.example.gmapsapp;

import android.os.Bundle;
import android.content.Intent;
import android.view.View;

public class homepage extends MainActivity {
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.layout1);



}
    public void onClick(View view)
    {
      Intent intent = new Intent(this, MainActivity.class);
        startActivity(intent);

    }
    public void onClick1(View view)
    {
      Intent intent = new Intent(this, Airports.class);
        startActivity(intent);
    }

    public void goback(View view)
    {

            Intent intent = new Intent(this, homepage.class);
            startActivity(intent);


    }

}

---

包含后退按钮的第二个活动

package com.example.gmapsapp;

import java.io.IOException;
import java.util.List;

import android.app.Dialog;
import android.location.Address;
import android.location.Geocoder;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.view.Menu;
import android.view.View;
import android.view.inputmethod.InputMethodManager;
import android.widget.EditText;
import android.widget.Toast;

import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GooglePlayServicesUtil;
import com.google.android.gms.maps.CameraUpdate;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;
public class MainActivity extends FragmentActivity {

    private static final int GPS_ERRORDIALOG_REQUEST = 9001;
    GoogleMap mMap;

    private static final double NASRCITY_LAT = 30.066108,
    NASRCITY_LNG =31.336184;
    private static final float DEFAULTZOOM = 13;

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

        if (servicesOK()) {
            setContentView(R.layout.activity_map);

            if (initMap()) {
                gotoLocation(NASRCITY_LAT, NASRCITY_LNG, DEFAULTZOOM);
            }
            else {
                Toast.makeText(this, "Map not available!", Toast.LENGTH_SHORT).show();
            }
        }
        else {
            setContentView(R.layout.activity_main);
        }

    }

    @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;
    }

    public boolean servicesOK() {
        int isAvailable = GooglePlayServicesUtil.isGooglePlayServicesAvailable(this);

        if (isAvailable == ConnectionResult.SUCCESS) {
            return true;
        }
        else if (GooglePlayServicesUtil.isUserRecoverableError(isAvailable)) {
            Dialog dialog = GooglePlayServicesUtil.getErrorDialog(isAvailable, this, GPS_ERRORDIALOG_REQUEST);
            dialog.show();
        }
        else {
            Toast.makeText(this, "Can't connect to Google Play services", Toast.LENGTH_SHORT).show();
        }
        return false;
    }

    private boolean initMap() {
        if (mMap == null) {
            SupportMapFragment mapFrag =
                    (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map);
            mMap = mapFrag.getMap();
        }
        if (mMap != null){
            setupmap();
        }
        return (mMap != null);
    }

    private void setupmap() {
mMap.addMarker(new MarkerOptions().position(new LatLng(30.060953, 31.357416)).title("Ahmed Hendy Pharmacy"));       
mMap.addMarker(new MarkerOptions().position(new LatLng(30.056645, 31.354756)).title("Hasan Ali Pharmacy"));     
mMap.addMarker(new MarkerOptions().position(new LatLng(30.051739, 31.355807)).title("Osama El-Meleegi's Pharmacy"));        
mMap.addMarker(new MarkerOptions().position(new LatLng(30.054673, 31.346751)).title("Ezaby Pharmacies"));       
mMap.addMarker(new MarkerOptions().position(new LatLng(30.054711, 31.35052)).title("pharmacies drug"));     
mMap.addMarker(new MarkerOptions().position(new LatLng(30.045609, 31.361686)).title("Maraghy tenth district"));     
mMap.addMarker(new MarkerOptions().position(new LatLng(30.040400, 31.329994)).title("Anji Pharmacy"));      
mMap.addMarker(new MarkerOptions().position(new LatLng(30.064593, 31.339916)).title("Amr Pharmacy"));       
mMap.addMarker(new MarkerOptions().position(new LatLng(30.056538, 31.338285)).title("Pharmacies Delmar and Atallah"));      
mMap.addMarker(new MarkerOptions().position(new LatLng(30.061886, 31.333264)).title("J. Bakl Pharmacy"));       

    }

    @SuppressWarnings("unused")
    private void gotoLocation(double lat, double lng) {
        LatLng ll = new LatLng(lat, lng);
        CameraUpdate update = CameraUpdateFactory.newLatLng(ll);
        mMap.moveCamera(update);
    }

    private void gotoLocation(double lat, double lng,
            float zoom) {
        LatLng ll = new LatLng(lat, lng);
        CameraUpdate update = CameraUpdateFactory.newLatLngZoom(ll, zoom);
        mMap.moveCamera(update);
    }

    public void geoLocate(View v) throws IOException {
        hideSoftKeyboard(v);

        EditText et = (EditText) findViewById(R.id.editText1);
        String location = et.getText().toString();

        Geocoder gc = new Geocoder(this);
        List<Address> list = gc.getFromLocationName(location, 1);
        Address add = list.get(0);
        String locality = add.getLocality();
        Toast.makeText(this, locality, Toast.LENGTH_LONG).show();

        double lat = add.getLatitude();
        double lng = add.getLongitude();

        gotoLocation(lat, lng, DEFAULTZOOM);

    }

    private void hideSoftKeyboard(View v) {
        InputMethodManager imm = (InputMethodManager)getSystemService(INPUT_METHOD_SERVICE);
        imm.hideSoftInputFromWindow(v.getWindowToken(), 0);
    }

}

按钮布局

<?xml version="1.0" encoding="utf-8"?>
<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="vertical"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin" >

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal" >

        <TextView
            android:id="@+id/textView1"
            android:layout_width="56dp"
            android:layout_height="35dp"
            android:layout_gravity="left|center_vertical"
            android:layout_weight="0.80"
            android:text="@string/Location"
            android:textSize="18sp" />

        <EditText
            android:id="@+id/editText1"
            android:layout_width="100dp"
            android:layout_height="wrap_content"
            android:layout_gravity="center|center_vertical"
            android:layout_weight="0.55"
            android:ems="10"
            android:inputType="textAutoComplete" >

            <requestFocus />
        </EditText>

        <Button
            android:id="@+id/button1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="right|center_vertical"
            android:onClick="geoLocate"
            android:text="@string/Go" />

        <Button
            android:id="@+id/button2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:onClick="goback"
            android:text="@string/Back" />

    </LinearLayout>

    <fragment
        android:id="@+id/map"
        android:name="com.google.android.gms.maps.SupportMapFragment"
        android:layout_width="match_parent"
        android:layout_height="fill_parent" />

</LinearLayout>

---

抱歉，英语不好

当您为视图声明

android:onClick

属性时，使用该布局的活动必须提供具有以下签名的方法：

public void nameSetInOnClick(View view) {

}

在您的示例中，您有

android:onClick=“goback”

，因此您必须提供一个名为

goback

的

public方法，该方法仅将视图对象作为参数：

public void goback(View view) {

}

包含“后退”按钮的第二个活动应具有如下方法：

public void goback(View v){

}

第二个活动的xml文件应该有如下设置

<Button
            android:id="@+id/button2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:onClick="goback"
            android:text="@string/Back" />


我编辑了这个函数，你的意思是什么？它仍然崩溃在哪个布局中你声明了那个按钮？请在MainActivitypost中移动goback方法日志猫它和我做的一样，但它崩溃后工作正常可能内存问题或其他问题，尝试解决它。
public void goback(View v){

}

<Button
            android:id="@+id/button2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:onClick="goback"
            android:text="@string/Back" />