[英]Button on fragment return null value pointer and crash the app
我試圖在片段中使用按鈕,但是當我嘗試實例化它時,該按鈕返回空指針並使應用程序崩潰。 這是我的代碼:
Questionario.xml
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent" android:layout_height="match_parent"
android:background="@color/Branco"
android:id="@+id/Questionario">
<ScrollView
android:layout_width="match_parent"
android:layout_height="fill_parent">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="@+id/Titulo1Quest"
android:layout_width="match_parent"
android:layout_height="50sp"
android:text="É membro do XV?"
android:layout_marginBottom="1sp"
android:layout_alignParentTop="true"
android:textSize="25sp"
android:padding="10sp"
android:textColor="@color/AzulPadrao"/>
<RadioGroup
android:layout_width="match_parent"
android:layout_height="30sp"
android:layout_below="@+id/Titulo1Quest"
android:orientation="horizontal"
android:gravity="center"
android:layout_marginTop="1sp"
android:id="@+id/RadioGroup1">
<RadioButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/Titulo1Quest"
android:text="Sim"
android:layout_marginLeft="10sp"
android:layout_marginRight="10sp"
android:gravity="center"
android:id="@+id/Rd1"
android:textSize="20sp"
android:textColor="@color/AzulPadrao"/>
<RadioButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/Titulo1Quest"
android:layout_toRightOf="@+id/Rd1"
android:text="Não"
android:layout_marginLeft="10sp"
android:layout_marginRight="10sp"
android:id="@+id/Rd2"
android:textSize="20sp"
android:textColor="@color/AzulPadrao"/>
</RadioGroup>
<View
android:layout_width="match_parent"
android:layout_height="1dp"
android:background="@color/Vermelho"
android:layout_below="@+id/RadioGroup1"
android:layout_margin="10sp"
android:id="@+id/Sep1"/>
<TextView
android:id="@+id/Titulo2Quest"
android:layout_width="match_parent"
android:layout_height="50sp"
android:text="Participa de quais ministérios?"
android:layout_marginBottom="1sp"
android:textSize="25sp"
android:padding="10sp"
android:textColor="@color/AzulPadrao"
android:layout_below="@+id/Sep1"/>
<GridLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/Titulo2Quest"
android:columnCount="2"
android:layout_marginBottom="15sp"
android:id="@+id/gridLayout">
<CheckBox
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Teatro"
android:id="@+id/cbTeatro"
android:layout_below="@+id/Titulo2Quest"
android:textColor="@color/AzulPadrao"
android:layout_alignParentLeft="true"
android:layout_marginLeft="10sp"
android:layout_marginRight="10sp"
android:textSize="20sp"/>
<CheckBox
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Infantil"
android:id="@+id/cbInfantil"
android:layout_below="@+id/Titulo2Quest"
android:textColor="@color/AzulPadrao"
android:layout_centerHorizontal="true"
android:layout_marginLeft="10sp"
android:layout_marginRight="10sp"
android:textSize="20sp"/>
<CheckBox
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Adolescente"
android:layout_weight="1"
android:layout_gravity="start"
android:id="@+id/cbAdolescente"
android:layout_below="@+id/cbTeatro"
android:textColor="@color/AzulPadrao"
android:layout_marginLeft="10sp"
android:layout_marginRight="10sp"
android:textSize="20sp"/>
<CheckBox
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Jovens"
android:id="@+id/cbJovens"
android:layout_below="@+id/cbInfantil"
android:textColor="@color/AzulPadrao"
android:layout_centerHorizontal="true"
android:layout_marginLeft="10sp"
android:layout_marginRight="10sp"
android:textSize="20sp"/>
<CheckBox
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Casados"
android:id="@+id/cbCasados"
android:layout_below="@+id/cbAdolescente"
android:textColor="@color/AzulPadrao"
android:layout_marginLeft="10sp"
android:layout_marginRight="10sp"
android:textSize="20sp"/>
<CheckBox
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Missões"
android:id="@+id/cbMissoes"
android:layout_below="@+id/cbJovens"
android:textColor="@color/AzulPadrao"
android:layout_centerHorizontal="true"
android:layout_marginLeft="10sp"
android:layout_marginRight="10sp"
android:textSize="20sp"/>
<CheckBox
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Diáconos"
android:id="@+id/cbDiaconos"
android:layout_below="@+id/cbCasados"
android:textColor="@color/AzulPadrao"
android:layout_marginLeft="10sp"
android:layout_marginRight="10sp"
android:textSize="20sp"/>
<CheckBox
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Mulheres"
android:id="@+id/cbMulheres"
android:layout_below="@+id/cbMissoes"
android:textColor="@color/AzulPadrao"
android:layout_centerHorizontal="true"
android:layout_marginLeft="10sp"
android:layout_marginRight="10sp"
android:textSize="20sp"/>
<CheckBox
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Dança"
android:id="@+id/cbDança"
android:textColor="@color/AzulPadrao"
android:layout_below="@+id/cbDiaconos"
android:layout_marginLeft="10sp"
android:layout_marginRight="10sp"
android:textSize="20sp"/>
<CheckBox
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Louvor"
android:id="@+id/cbLouvor"
android:textColor="@color/AzulPadrao"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_marginLeft="10sp"
android:layout_marginRight="10sp"
android:textSize="20sp"/>
</GridLayout>
<View
android:layout_width="match_parent"
android:layout_height="1dp"
android:background="@color/Vermelho"
android:id="@+id/Sep2"
android:layout_below="@id/gridLayout"
android:layout_margin="10sp"/>
<Button
android:id="@+id/btQuestionario"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:background="@color/AzulPadrao"
android:text="OK"
android:layout_marginTop="10sp"
android:textColor="@android:color/white"
android:layout_below="@id/Sep2"
android:layout_marginLeft="40sp"
android:layout_marginRight="40sp"
android:clickable="true"/>
</RelativeLayout>
</ScrollView>
</FrameLayout>
Canais.java
package igparadaxv.igbparadaxv.Parse;
import android.app.Activity;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.TextView;
import java.util.ArrayList;
import java.util.List;
import igparadaxv.igbparadaxv.Home.homeActivity;
import igparadaxv.igbparadaxv.R;
public class Canais extends Fragment {
ArrayList<String> canais;
RadioButton sim;
RadioButton nao;
CheckBox teatro;
CheckBox adolescente;
CheckBox casados;
CheckBox danca;
CheckBox diaconos;
CheckBox infantil;
CheckBox jovens;
CheckBox louvor;
CheckBox missoes;
CheckBox mulheres;
Button ok;
public Canais() {
// Required empty public constructor
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ok = (Button)getActivity().findViewById(R.id.btQuestionario);
ok.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
}
});
/*Radio Buttons*/
sim = (RadioButton) getActivity().findViewById(R.id.Rd1);
nao = (RadioButton) getActivity().findViewById(R.id.Rd2);
/*Check box*/
teatro = (CheckBox) getActivity().findViewById(R.id.cbTeatro);
adolescente = (CheckBox) getActivity().findViewById(R.id.cbAdolescente);
casados = (CheckBox) getActivity().findViewById(R.id.cbCasados);
danca = (CheckBox) getActivity().findViewById(R.id.cbDança);
diaconos = (CheckBox) getActivity().findViewById(R.id.cbDiaconos);
infantil = (CheckBox) getActivity().findViewById(R.id.cbInfantil);
jovens = (CheckBox) getActivity().findViewById(R.id.cbJovens);
louvor = (CheckBox) getActivity().findViewById(R.id.cbLouvor);
missoes = (CheckBox) getActivity().findViewById(R.id.cbMissoes);
mulheres = (CheckBox) getActivity().findViewById(R.id.cbMulheres);
RadioGroup radioGroup = (RadioGroup) getActivity().findViewById(R.id.RadioGroup1);
radioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(RadioGroup group, int checkedId) {
if(checkedId == sim.getId()){
teatro.setEnabled(true);
adolescente.setEnabled(true);
casados.setEnabled(true);
danca.setEnabled(true);
diaconos.setEnabled(true);
infantil.setEnabled(true);
jovens.setEnabled(true);
louvor.setEnabled(true);
missoes.setEnabled(true);
mulheres.setEnabled(true);
}else{
teatro.setEnabled(false);
adolescente.setEnabled(false);
casados.setEnabled(false);
danca.setEnabled(false);
diaconos.setEnabled(false);
infantil.setEnabled(false);
jovens.setEnabled(false);
louvor.setEnabled(false);
missoes.setEnabled(false);
mulheres.setEnabled(false);
}
}
});
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.questionario, container, false);
}
public void canais()
{
if(teatro.isChecked())
{
canais.add("Teatro");
}
if(adolescente.isChecked())
{
canais.add("Adolescente");
}
if(casados.isChecked())
{
canais.add("Casados");
}
if(danca.isChecked())
{
canais.add("Danca");
}
if(diaconos.isChecked())
{
canais.add("Diaconos");
}
if(infantil.isChecked())
{
canais.add("Infantil");
}
if(jovens.isChecked())
{
canais.add("Jovens");
}
if(louvor.isChecked())
{
canais.add("Louvor");
}
if(missoes.isChecked())
{
canais.add("Missoes");
}
if(mulheres.isChecked())
{
canais.add("Louvor");
}
ParseUtils.subscribeMultipleChannels(canais);
home();
}
private void home() {
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.remove(this);
Intent intent = new Intent(getActivity(),homeActivity.class);
startActivity(intent);
}
}
我還有一部分代碼將按鈕使用到片段中,但是僅在此特定部分中不起作用。
該按鈕返回一個空指針並使應用程序崩潰
正如看到在片段 onCreate
方法之前調用onCreateView
和當前查看片段屏幕是從返回onCreateView
使用下面的行:
return inflater.inflate(R.layout.questionario, container, false);
這就是為什么在向Button添加點擊偵聽器時獲取NullPointerException
的原因。
代替使用onCreate
方法,可以使用onCreateView
或onViewCreated
來訪問片段布局,該片段布局是從onCreateView
返回的。
像在onCreateView
方法中訪問Button一樣:
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view =inflater.inflate(R.layout.questionario, container, false);
ok = (Button)view.findViewById(R.id.btQuestionario);
// add click listener for Button here
// do same for accessing other Views
return view;
}
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