单击后退图标而不是 Android 中的完整工具栏时如何导航到上一个 activity?
How to navigate to previous activity when back icon is clicked instead of the complete toolbar in Android?
我正在开发一个 android 应用程序,想从当前的 activity 导航到上一个 activity。
在这里,我想从 SecondActivity 导航回 MainActivity。我添加了一个工具栏和一个后退图标,点击后应该会返回到之前的 activity。但在这里,完整的工具栏在单击时导航回之前的 activity。
SecondActivity.java
package com.example.acer.videoapp;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.Toast;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
import java.util.HashMap;
public class SecondActivity extends AppCompatActivity {
private String TAG = MainActivity.class.getSimpleName();
private ProgressDialog pDialog;
private ListView listView1;
Toolbar toolbar1;
String subjectName;
ArrayList<HashMap<String, String>> lessonList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_second);
//setting title to toolbar
toolbar1 = (Toolbar) findViewById(R.id.toolbar1);
Bundle bundle = getIntent().getExtras();
if(bundle!=null) {
toolbar1.setTitle(bundle.getString("Subject"));
subjectName=toolbar1.getTitle().toString();
}
lessonList = new ArrayList<>();
listView1 = (ListView) findViewById(R.id.list);
new GetLessons().execute();
listView1.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int i, long id) {
Intent intent = new Intent(SecondActivity.this, ThirdActivity.class);
HashMap<String, String> lesson = lessonList.get(i);
intent.putExtra("number", lesson.get("number"));
intent.putExtra("name", lesson.get("name"));
//intent.putExtra("subject", listView1.getItemAtPosition(i).toString());
startActivity(intent);
}
});
//back navigation
toolbar1.setNavigationIcon(R.drawable.back);
toolbar1.setNavigationOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startActivity(new Intent(getApplicationContext(),MainActivity.class));
}
});
}
/* Async task class to get json by making HTTP call */
private class GetLessons extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
super.onPreExecute();
// Showing progress dialog
pDialog = new ProgressDialog(SecondActivity.this);
pDialog.setMessage("Please wait...");
pDialog.setCancelable(false);
pDialog.show();
}
@Override
protected Void doInBackground(Void... arg0) {
HttpHandler sh = new HttpHandler();
// Making a request to url and getting response
String url = getResources().getString(R.string.lessons_url, subjectName);
String jsonStr = sh.makeServiceCall(url);
Log.e(TAG, "Response from url: " + jsonStr);
if (jsonStr != null) {
try {
// Getting JSON Array
JSONArray lessons = new JSONArray(jsonStr);
// looping through All lessons
for (int i = 0; i < lessons.length(); i++) {
JSONObject c = lessons.getJSONObject(i);
String number = c.getString("lessonNo");
String name = c.getString("lessonName");
// tmp hash map for single lesson
HashMap<String, String> lesson = new HashMap<>();
// adding each child node to HashMap key => value
lesson.put("number", number);
lesson.put("name", name);
// adding lesson to lesson list
lessonList.add(lesson);
}
} catch (final JSONException e) {
Log.e(TAG, "Json parsing error: " + e.getMessage());
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(getApplicationContext(),"Json parsing error: " + e.getMessage(),Toast.LENGTH_LONG).show();
}
});
}
} else {
Log.e(TAG, "Couldn't get json from server.");
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(getApplicationContext(),"Couldn't get json from server. Check LogCat for possible errors!",Toast.LENGTH_LONG).show();
}
});
}
return null;
}
@Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
// Dismiss the progress dialog
if (pDialog.isShowing())
pDialog.dismiss();
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(
SecondActivity.this, lessonList,R.layout.list_item, new String[]{"number", "name",}, new int[]{R.id.lnumber,R.id.lname});
listView1.setAdapter(adapter);
}
}
}
activity_second.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"
tools:context="com.example.acer.videoapp.SecondActivity">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:background="@color/blue"
android.theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
/>
<ListView
android:id="@+id/list"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:layout_below="@+id/toolbar1"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
/>
</RelativeLayout>
非常简单,点击导航图标即可调用 onBackPressed()
toolbar1.setNavigationIcon(R.drawable.back);
toolbar1.setNavigationOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
onBackPressed();
}
});
我正在开发一个 android 应用程序,想从当前的 activity 导航到上一个 activity。
在这里,我想从 SecondActivity 导航回 MainActivity。我添加了一个工具栏和一个后退图标,点击后应该会返回到之前的 activity。但在这里,完整的工具栏在单击时导航回之前的 activity。
SecondActivity.java
package com.example.acer.videoapp;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.Toast;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
import java.util.HashMap;
public class SecondActivity extends AppCompatActivity {
private String TAG = MainActivity.class.getSimpleName();
private ProgressDialog pDialog;
private ListView listView1;
Toolbar toolbar1;
String subjectName;
ArrayList<HashMap<String, String>> lessonList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_second);
//setting title to toolbar
toolbar1 = (Toolbar) findViewById(R.id.toolbar1);
Bundle bundle = getIntent().getExtras();
if(bundle!=null) {
toolbar1.setTitle(bundle.getString("Subject"));
subjectName=toolbar1.getTitle().toString();
}
lessonList = new ArrayList<>();
listView1 = (ListView) findViewById(R.id.list);
new GetLessons().execute();
listView1.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int i, long id) {
Intent intent = new Intent(SecondActivity.this, ThirdActivity.class);
HashMap<String, String> lesson = lessonList.get(i);
intent.putExtra("number", lesson.get("number"));
intent.putExtra("name", lesson.get("name"));
//intent.putExtra("subject", listView1.getItemAtPosition(i).toString());
startActivity(intent);
}
});
//back navigation
toolbar1.setNavigationIcon(R.drawable.back);
toolbar1.setNavigationOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startActivity(new Intent(getApplicationContext(),MainActivity.class));
}
});
}
/* Async task class to get json by making HTTP call */
private class GetLessons extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
super.onPreExecute();
// Showing progress dialog
pDialog = new ProgressDialog(SecondActivity.this);
pDialog.setMessage("Please wait...");
pDialog.setCancelable(false);
pDialog.show();
}
@Override
protected Void doInBackground(Void... arg0) {
HttpHandler sh = new HttpHandler();
// Making a request to url and getting response
String url = getResources().getString(R.string.lessons_url, subjectName);
String jsonStr = sh.makeServiceCall(url);
Log.e(TAG, "Response from url: " + jsonStr);
if (jsonStr != null) {
try {
// Getting JSON Array
JSONArray lessons = new JSONArray(jsonStr);
// looping through All lessons
for (int i = 0; i < lessons.length(); i++) {
JSONObject c = lessons.getJSONObject(i);
String number = c.getString("lessonNo");
String name = c.getString("lessonName");
// tmp hash map for single lesson
HashMap<String, String> lesson = new HashMap<>();
// adding each child node to HashMap key => value
lesson.put("number", number);
lesson.put("name", name);
// adding lesson to lesson list
lessonList.add(lesson);
}
} catch (final JSONException e) {
Log.e(TAG, "Json parsing error: " + e.getMessage());
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(getApplicationContext(),"Json parsing error: " + e.getMessage(),Toast.LENGTH_LONG).show();
}
});
}
} else {
Log.e(TAG, "Couldn't get json from server.");
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(getApplicationContext(),"Couldn't get json from server. Check LogCat for possible errors!",Toast.LENGTH_LONG).show();
}
});
}
return null;
}
@Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
// Dismiss the progress dialog
if (pDialog.isShowing())
pDialog.dismiss();
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(
SecondActivity.this, lessonList,R.layout.list_item, new String[]{"number", "name",}, new int[]{R.id.lnumber,R.id.lname});
listView1.setAdapter(adapter);
}
}
}
activity_second.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"
tools:context="com.example.acer.videoapp.SecondActivity">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:background="@color/blue"
android.theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
/>
<ListView
android:id="@+id/list"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:layout_below="@+id/toolbar1"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
/>
</RelativeLayout>
非常简单,点击导航图标即可调用 onBackPressed()
toolbar1.setNavigationIcon(R.drawable.back);
toolbar1.setNavigationOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
onBackPressed();
}
});