Java 方向改变时应用程序崩溃
为了学习,我正在申请。。当我在按下屏幕上的任何按钮之前改变方向时。。它成功地改变了方向,并显示了我添加到“layout land”文件夹中的相应布局 但当我按下按钮显示下一个片段,然后切换方向。。我希望活动重新启动,但我的应用程序崩溃。。。我需要帮助 调试器不显示引发任何异常的行 main活动类Java 方向改变时应用程序崩溃,java,android,Java,Android,为了学习,我正在申请。。当我在按下屏幕上的任何按钮之前改变方向时。。它成功地改变了方向,并显示了我添加到“layout land”文件夹中的相应布局 但当我按下按钮显示下一个片段,然后切换方向。。我希望活动重新启动,但我的应用程序崩溃。。。我需要帮助 调试器不显示引发任何异常的行 main活动类 package com.example.prototype; import android.os.Bundle; import android.support.v4.app.FragmentActiv
package com.example.prototype;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentTransaction;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import com.example.prototype.fragments.FragmentOne;
public class MainActivity extends FragmentActivity {
int fragShowButtonPressed =0;
boolean FragOneDisplayed=false;
boolean FragTwoDisplayed=false;
public void fragment_switch(View v){
Button showfrag1 = (Button)findViewById(R.id.buttonShowFrag1);
Button showfrag2 = (Button)findViewById(R.id.buttonShowFrag2);
showfrag1.setVisibility(showfrag1.INVISIBLE);
showfrag2.setVisibility(showfrag2.INVISIBLE);
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
switch(v.getId()){
case(R.id.buttonShowFrag1): ft.replace(R.id.frameLayout1, new FragmentOne("frag_1"), null); fragShowButtonPressed=1; FragOneDisplayed=true; FragTwoDisplayed=false; break;
case(R.id.buttonShowFrag2): ft.replace(R.id.frameLayout1, new FragmentOne("frag_2"), null); fragShowButtonPressed=1; FragOneDisplayed=false; FragTwoDisplayed=true; break;
}
ft.addToBackStack(null);
ft.commit();
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.i("create", "Entered Oncreate");
setContentView(R.layout.activity_main);
if(savedInstanceState != null){
if(savedInstanceState.getInt("frag_button_pressed_stat")==1)
{
Button showfrag1 = (Button)findViewById(R.id.buttonShowFrag1);
Button showfrag2 = (Button)findViewById(R.id.buttonShowFrag2);
showfrag1.setVisibility(showfrag1.INVISIBLE);
showfrag2.setVisibility(showfrag2.INVISIBLE);
FragOneDisplayed=savedInstanceState.getBoolean("frag_one_display_stat");
FragTwoDisplayed=savedInstanceState.getBoolean("frag_two_display_stat");
}
else{}
}
}
@Override
protected void onSaveInstanceState(Bundle outState) {
if(fragShowButtonPressed ==1)
{
outState.putInt("frag_button_pressed_stat", fragShowButtonPressed);
outState.putBoolean("frag_one_display_stat", FragOneDisplayed);
outState.putBoolean("frag_two_display_stat", FragTwoDisplayed);
}
super.onSaveInstanceState(outState);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
零碎一类
package com.example.prototype.fragments;
import com.example.prototype.R;
import android.content.Context;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class FragmentOne extends Fragment {
int id;
Context context;
public FragmentOne(String frag_name){
if(frag_name=="frag_1")
{
id=R.layout.frag_1;
}
else if(frag_name == "frag_2"){
id=R.layout.frag_2;
}
else{}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
context = inflater.getContext();
View v=inflater.inflate(id, container, false);
return v;
}
}
请注意,当我使用空构造函数创建不同的片段类并直接提供int-XML资源来膨胀()函数时,问题就解决了
package com.example.prototype;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentTransaction;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import com.example.prototype.fragments.FragmentOne;
public class MainActivity extends FragmentActivity {
int fragShowButtonPressed =0;
boolean FragOneDisplayed=false;
boolean FragTwoDisplayed=false;
public void fragment_switch(View v){
Button showfrag1 = (Button)findViewById(R.id.buttonShowFrag1);
Button showfrag2 = (Button)findViewById(R.id.buttonShowFrag2);
showfrag1.setVisibility(showfrag1.INVISIBLE);
showfrag2.setVisibility(showfrag2.INVISIBLE);
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
switch(v.getId()){
case(R.id.buttonShowFrag1): ft.replace(R.id.frameLayout1, new FragmentOne("frag_1"), null); fragShowButtonPressed=1; FragOneDisplayed=true; FragTwoDisplayed=false; break;
case(R.id.buttonShowFrag2): ft.replace(R.id.frameLayout1, new FragmentOne("frag_2"), null); fragShowButtonPressed=1; FragOneDisplayed=false; FragTwoDisplayed=true; break;
}
ft.addToBackStack(null);
ft.commit();
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.i("create", "Entered Oncreate");
setContentView(R.layout.activity_main);
if(savedInstanceState != null){
if(savedInstanceState.getInt("frag_button_pressed_stat")==1)
{
Button showfrag1 = (Button)findViewById(R.id.buttonShowFrag1);
Button showfrag2 = (Button)findViewById(R.id.buttonShowFrag2);
showfrag1.setVisibility(showfrag1.INVISIBLE);
showfrag2.setVisibility(showfrag2.INVISIBLE);
FragOneDisplayed=savedInstanceState.getBoolean("frag_one_display_stat");
FragTwoDisplayed=savedInstanceState.getBoolean("frag_two_display_stat");
}
else{}
}
}
@Override
protected void onSaveInstanceState(Bundle outState) {
if(fragShowButtonPressed ==1)
{
outState.putInt("frag_button_pressed_stat", fragShowButtonPressed);
outState.putBoolean("frag_one_display_stat", FragOneDisplayed);
outState.putBoolean("frag_two_display_stat", FragTwoDisplayed);
}
super.onSaveInstanceState(outState);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
泰穆尔阿里,谢谢
日志目录
07-09 23:35:45.387: E/AndroidRuntime(948): FATAL EXCEPTION: main
07-09 23:35:45.387: E/AndroidRuntime(948): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.prototype/com.example.prototype.MainActivity}: android.support.v4.app.Fragment$InstantiationException: Unable to instantiate fragment com.example.prototype.fragments.FragmentOne: make sure class name exists, is public, and has an empty constructor that is public
07-09 23:35:45.387: E/AndroidRuntime(948): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2205)
07-09 23:35:45.387: E/AndroidRuntime(948): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2240)
07-09 23:35:45.387: E/AndroidRuntime(948): at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:3809)
07-09 23:35:45.387: E/AndroidRuntime(948): at android.app.ActivityThread.access$700(ActivityThread.java:139)
07-09 23:35:45.387: E/AndroidRuntime(948): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1266)
07-09 23:35:45.387: E/AndroidRuntime(948): at android.os.Handler.dispatchMessage(Handler.java:99)
07-09 23:35:45.387: E/AndroidRuntime(948): at android.os.Looper.loop(Looper.java:156)
07-09 23:35:45.387: E/AndroidRuntime(948): at android.app.ActivityThread.main(ActivityThread.java:4987)
07-09 23:35:45.387: E/AndroidRuntime(948): at java.lang.reflect.Method.invokeNative(Native Method)
07-09 23:35:45.387: E/AndroidRuntime(948): at java.lang.reflect.Method.invoke(Method.java:511)
07-09 23:35:45.387: E/AndroidRuntime(948): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
07-09 23:35:45.387: E/AndroidRuntime(948): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
07-09 23:35:45.387: E/AndroidRuntime(948): at dalvik.system.NativeStart.main(Native Method)
07-09 23:35:45.387: E/AndroidRuntime(948): Caused by: android.support.v4.app.Fragment$InstantiationException: Unable to instantiate fragment com.example.prototype.fragments.FragmentOne: make sure class name exists, is public, and has an empty constructor that is public
07-09 23:35:45.387: E/AndroidRuntime(948): at android.support.v4.app.Fragment.instantiate(Fragment.java:405)
07-09 23:35:45.387: E/AndroidRuntime(948): at android.support.v4.app.FragmentState.instantiate(Fragment.java:97)
07-09 23:35:45.387: E/AndroidRuntime(948): at android.support.v4.app.FragmentManagerImpl.restoreAllState(FragmentManager.java:1767)
07-09 23:35:45.387: E/AndroidRuntime(948): at android.support.v4.app.FragmentActivity.onCreate(FragmentActivity.java:208)
07-09 23:35:45.387: E/AndroidRuntime(948): at com.example.prototype.MainActivity.onCreate(MainActivity.java:44)
07-09 23:35:45.387: E/AndroidRuntime(948): at android.app.Activity.performCreate(Activity.java:4538)
07-09 23:35:45.387: E/AndroidRuntime(948): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1071)
07-09 23:35:45.387: E/AndroidRuntime(948): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2161)
07-09 23:35:45.387: E/AndroidRuntime(948): ... 12 more
07-09 23:35:45.387: E/AndroidRuntime(948): Caused by: java.lang.InstantiationException: can't instantiate class com.example.prototype.fragments.FragmentOne; no empty constructor
07-09 23:35:45.387: E/AndroidRuntime(948): at java.lang.Class.newInstanceImpl(Native Method)
07-09 23:35:45.387: E/AndroidRuntime(948): at java.lang.Class.newInstance(Class.java:1319)
07-09 23:35:45.387: E/AndroidRuntime(948): at android.support.v4.app.Fragment.instantiate(Fragment.java:394)
07-09 23:35:45.387: E/AndroidRuntime(948): ... 19 more
错误提示您的片段没有空构造函数: 07-09 23:35:45.387:E/AndroidRuntime(948):原因:java.lang.InstantiationException:无法实例化类com.example.prototype.FragmentOne;没有空构造函数 您需要一个关于配置更改的配置,因为您的片段正在重建中 您需要以不同的方式实例化片段中的数据,例如:
public static final GridFragment newInstance(String tabId)
{
GridFragment f = new GridFragment();
Bundle bdl = new Bundle(2);
bdl.putString(TAB_ID, tabId);
f.setArguments(bdl);
return f;
}
@Override
public void onCreate(Bundle savedInstanceState)
{
String tabId = getArguments().getString(TAB_ID);
if (application.currentReport != null)
{
this.odTab = application.currentReport.getODTabByTabId(tabId);
}
else
{
startActivity(new Intent(getActivity(), LoginScrActivity.class));
}
super.onCreate(savedInstanceState);
}
这样,构造函数仍然为空,但您正在传递所需的字符串,另请参见以下问题:
对于片段,必须有空构造函数(不带参数)或无构造函数(默认值)。如果要传递参数,请使用参数创建一个
包
,并使用setArguments
这通常通过静态创建方法实现:
class MyFragment extends Fragment {
public static MyFragment newInstance(String name) {
MyFragment f = new MyFragment();
Bundle args = new Bundle();
args.putString("name", name);
f.setArguments(bundle);
return f;
}
...
}
但在您的情况下,只需发送布局的id?任何替代方案都是因为有5个xml布局,我无法创建5个不同的片段类,必须有一种方法将它们组合在一个类@Emil中Adz@TaimoorAli,我只是在早些时候发布了相同的代码。它没有帮到你?我添加了这个视图v=inflater.inflate(getArguments().getInt(“id”),container,false)。。。在我的activityclass方法中,我编写了FragmentOne frt=new FragmentOne();第一个新实例(R.layout.frag_1);现在我应该写什么作为replace函数的第二个参数。。这就是我写的ft.replace(R.id.frameLayout1,frt,null)指向何处开始的任何链接,你能告诉我如何做吗,因为我有5种不同的XML布局,我想使用类似的方法来更改片段。。。。你能告诉我密码吗。。感谢您展示Alternative官方android开发者文档非常好。下面是片段部分中的一个示例:请注意,他们在DetailsFragment中是如何使用项的id作为参数创建它的。一般来说,您可能应该为不同的布局使用不同的片段,但很难说。取决于它们的不同之处(或目的)。祝你好运我添加了这个视图v=inflater.inflate(getArguments().getInt(“id”),container,false)。。。在我的activityclass方法中,我编写了FragmentOne frt=new FragmentOne();第一个新实例(R.layout.frag_1);现在我应该写什么作为replace函数的第二个参数。。这是我写的ft.replace(R.id.frameLayout1,frt,null)@Mattias做到了谢谢。。。非常感谢你