关于android：app在findViewById（）上崩溃

App crashes on findViewById()

本问题已经有最佳答案，请猛点这里访问。

所以我在activity_main.xml中有一个listview。另一个是另一个xml da_item.xml中的文本视图。textView用于单个listView项。

现在在我的代码中有一个onContextItemSelected()函数，它调用bucketmarkItem(long itemtitle)。bucketmarkitem(long itemtitle)使用函数colorcorrection()更改最后一个项的背景色。

整个代码工作正常。

但是我有一个按钮，上面有entertitem()onclick listener。我从EnterItem()内部调用相同的colorcorrection()，应用程序崩溃。它在这条线上崩溃了。

1	TextView txtDep1=(TextView)listItemBla1.findViewById(R.id.tv);

我不知道为什么。

我看到过许多这样的问题，答案是使用setContentView(r.layout.activityu main)，但我已经包含了这个问题。

OnContextItemSelected代码

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@Override
public boolean onContextItemSelected(MenuItem item) {
// TODO Auto-generated method stub
super.onContextItemSelected(item);

AdapterContextMenuInfo info = (AdapterContextMenuInfo) item.getMenuInfo();
long hula = info.id;

if(item.getTitle()=="Mark as Done"){
bucketMarkItem(hula);
}
if(item.getTitle()=="Mark as Undone"){
bucketUnMarkItem(hula);
}
if(item.getTitle()=="Delete Item"){
bucketDeletelistItem(hula);
}

return true;
}

bucketmarkitem()代码

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private void bucketMarkItem(long itemTitle) {
// TODO Auto-generated method stub
View listItemBla=(View)list.getChildAt((int)(long)itemTitle);
TextView txtDep=(TextView)listItemBla.findViewById(R.id.tv);
txtDep.setBackgroundColor(Color.GREEN);

String txtDepText =""+txtDep.getText();
String[] result = txtDepText.split("");
String result1 = result[1];

Cursor cursor = myDB.getAllRows();

if(cursor.moveToFirst()){
do{
if(result1.equals(cursor.getString(1))){
long yourDBID = yourDB.insertRow(cursor.getInt(0));
}
}while(cursor.moveToNext());
}
cursor.close();
colorCorrecton();
}

颜色校正代码

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private void colorCorrecton() {

Toast.makeText(MainActivity.this,""+ list.getCount(), Toast.LENGTH_SHORT).show();

View listItemBla1=(View)list.getChildAt((list.getCount()-1));
TextView txtDep1=(TextView)listItemBla1.findViewById(R.id.tv);

Toast.makeText(MainActivity.this,""+txtDep1.getText(), Toast.LENGTH_SHORT).show();
txtDep.setBackgroundColor(Color.GREEN);
}

EnterItem()代码

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public void enterItem(View v) {
// TODO Auto-generated method stub
EditText dataEntry_EditText=(EditText)findViewById(R.id.editText1);
Editable dataEntry_Editable = dataEntry_EditText.getText();
String dataEntry_Finaldata = dataEntry_Editable.toString();
long newId = myDB.insertRow(dataEntry_Finaldata, 233,"red");

//Toast.makeText(MainActivity.this, dataEntry_Finaldata, Toast.LENGTH_LONG).show();
dataEntry_EditText.setText("");

populateListView();

//Toast.makeText(MainActivity.this,""+list.getCount(), Toast.LENGTH_LONG).show();
colorCorrecton();
}

完整代码

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package com.example.bucketlist;

import java.util.ArrayList;

import android.support.v4.app.FragmentActivity;
import android.text.Editable;
import android.database.Cursor;
import android.graphics.Color;
import android.os.Bundle;
import android.view.ContextMenu;
import android.view.MenuItem;
import android.view.View;
import android.view.ContextMenu.ContextMenuInfo;
import android.widget.AdapterView.AdapterContextMenuInfo;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends FragmentActivity {

ListView list;
DBAdapter myDB;
DBAdapter1 yourDB;

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

ImageView bucketMenu = (ImageView)findViewById(R.id.bucketMenuW);
list= (ListView)findViewById(R.id.listView1);
registerForContextMenu(list);
openDB();
populateListView();
//colorCorrecton();

}

private void colorCorrecton() {

Toast.makeText(MainActivity.this,""+ list.getCount(), Toast.LENGTH_SHORT).show();

View listItemBla1=(View)list.getChildAt((list.getCount()-1));
TextView txtDep1=(TextView)listItemBla1.findViewById(R.id.tv);

Toast.makeText(MainActivity.this,""+txtDep1.getText(), Toast.LENGTH_SHORT).show();
//txtDep.setBackgroundColor(Color.GREEN);
}

public void conMenu(View v) {
// TODO Auto-generated method stub
}

@Override
public void onCreateContextMenu(ContextMenu menu, View v,
ContextMenuInfo menuInfo) {
// TODO Auto-generated method stub
super.onCreateContextMenu(menu, v, menuInfo);

if(v.getId()==R.id.listView1){
menu.add("Mark as Done");
menu.add("Mark as Undone");
menu.add("Delete Item");
}
}

@Override
public boolean onContextItemSelected(MenuItem item) {
// TODO Auto-generated method stub
super.onContextItemSelected(item);

AdapterContextMenuInfo info = (AdapterContextMenuInfo) item.getMenuInfo();
long hula = info.id;

if(item.getTitle()=="Mark as Done"){
bucketMarkItem(hula);
}
if(item.getTitle()=="Mark as Undone"){
bucketUnMarkItem(hula);
}
if(item.getTitle()=="Delete Item"){
bucketDeletelistItem(hula);
}

return true;
}

private void bucketUnMarkItem(long itemTitle) {
// TODO Auto-generated method stub
View listItemBla=(View)list.getChildAt((int)(long)itemTitle);
TextView txtDep=(TextView)listItemBla.findViewById(R.id.tv);
String txtDepText =""+txtDep.getText();
String[] result = txtDepText.split("");
String result1 = result[1];

Cursor cursor = myDB.getAllRows();

int markID=0;
if(cursor.moveToFirst()){
do{
if(result1.equals(cursor.getString(1))){
markID = cursor.getInt(0);
}
}while(cursor.moveToNext());
}
cursor.close();
//Toast.makeText(MainActivity.this,""+list.getCount(), Toast.LENGTH_LONG).show();

Cursor cursor1 = yourDB.getAllRows();

if(cursor1.moveToFirst()){
do{
if(markID == cursor1.getInt(1)){
boolean newid2 = yourDB.deleteRow(cursor1.getInt(0));
}
}while(cursor1.moveToNext());
}
cursor1.close();

colorCorrecton();
}

private void bucketMarkItem(long itemTitle) {
// TODO Auto-generated method stub
View listItemBla=(View)list.getChildAt((int)(long)itemTitle);
TextView txtDep=(TextView)listItemBla.findViewById(R.id.tv);
txtDep.setBackgroundColor(Color.GREEN);

String txtDepText =""+txtDep.getText();
String[] result = txtDepText.split("");
String result1 = result[1];

Cursor cursor = myDB.getAllRows();

if(cursor.moveToFirst()){
do{
if(result1.equals(cursor.getString(1))){
long yourDBID = yourDB.insertRow(cursor.getInt(0));
}
}while(cursor.moveToNext());
}
cursor.close();
}

public void deleteItem(View v) {
// TODO Auto-generated method stub
myDB.deleteAll();
yourDB.deleteAll();
populateListView();
}

private void bucketDeletelistItem(long itemTitle) {
View listItemBla=(View)list.getChildAt((int)(long)itemTitle);
TextView txtDep=(TextView)listItemBla.findViewById(R.id.tv);
String txtDepText =""+txtDep.getText();
String[] result = txtDepText.split("");
String result1 = result[1];

Cursor cursor = myDB.getAllRows();

int markID=0;
if(cursor.moveToFirst()){
do{
if(result1.equals(cursor.getString(1))){
boolean newid1 = myDB.deleteRow(cursor.getInt(0));
markID = cursor.getInt(0);
}
}while(cursor.moveToNext());
}
cursor.close();
populateListView();
//Toast.makeText(MainActivity.this,""+list.getCount(), Toast.LENGTH_LONG).show();

Cursor cursor1 = yourDB.getAllRows();

if(cursor1.moveToFirst()){
do{
if(markID == cursor1.getInt(1)){
boolean newid2 = yourDB.deleteRow(cursor1.getInt(0));
}
}while(cursor1.moveToNext());
}
cursor1.close();

colorCorrecton();
}

public void enterItem(View v) {
// TODO Auto-generated method stub
EditText dataEntry_EditText=(EditText)findViewById(R.id.editText1);
Editable dataEntry_Editable = dataEntry_EditText.getText();
String dataEntry_Finaldata = dataEntry_Editable.toString();
long newId = myDB.insertRow(dataEntry_Finaldata, 233,"red");

//Toast.makeText(MainActivity.this, dataEntry_Finaldata, Toast.LENGTH_LONG).show();
dataEntry_EditText.setText("");

populateListView();

//Toast.makeText(MainActivity.this,""+list.getCount(), Toast.LENGTH_LONG).show();
colorCorrecton();
}

@Override
protected void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
closeDB();
}

private void closeDB() {
// TODO Auto-generated method stub
myDB.close();
}

private void openDB() {
// TODO Auto-generated method stub
myDB = new DBAdapter(this);
yourDB = new DBAdapter1(this);
myDB.open();
yourDB.open();
}

private void populateListView() {
// TODO Auto-generated method stub

Cursor cursor = myDB.getAllRows();
ArrayList<String> myItems = new ArrayList<String>();
//String[] myItems = {};

if(cursor.moveToFirst()){
int countData=0;
do{
countData=countData+1;
int id = cursor.getInt(0);
String name ="#"+countData +"-"+ cursor.getString(1);
myItems.add(name);
}while(cursor.moveToNext());
}
cursor.close();

ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,R.layout.da_item,myItems);

list.setAdapter(adapter);

//Toast.makeText(MainActivity.this, Integer.toString(list.getFirstVisiblePosition())+","+Integer.toString(list.getLastVisiblePosition()), Toast.LENGTH_LONG).show();
//View v = list.getChildAt(0);
//v.setBackgroundColor(005566);
//View listItemBla=(View)list.getChildAt(list.getFirstVisiblePosition());
//Toast.makeText(MainActivity.this,""+ list.getChildCount(), Toast.LENGTH_LONG).show();
//TextView txtDep=(TextView)listItemBla.findViewById(R.id.tv);
//txtDep.setBackgroundColor(Color.parseColor("00FF00"));
}

}

洛卡特

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06-21 09:46:13.656: D/libEGL(24175): loaded /system/lib/egl/libEGL_adreno200.so
06-21 09:46:13.656: D/libEGL(24175): loaded /system/lib/egl/libGLESv1_CM_adreno200.so
06-21 09:46:13.656: D/libEGL(24175): loaded /system/lib/egl/libGLESv2_adreno200.so
06-21 09:46:13.666: I/Adreno200-EGL(24175): <qeglDrvAPI_eglInitialize:265>: EGL 1.4 QUALCOMM build: AU_LINUX_ANDROID_JB_2.5.04.02.02.040.400_msm8960_JB_2.5_CL3744273_release_AU (CL3744273)
06-21 09:46:13.666: I/Adreno200-EGL(24175): Build Date: 06/30/13 Sun
06-21 09:46:13.666: I/Adreno200-EGL(24175): Local Branch:
06-21 09:46:13.666: I/Adreno200-EGL(24175): Remote Branch: quic/jb_2.5
06-21 09:46:13.666: I/Adreno200-EGL(24175): Local Patches: NONE
06-21 09:46:13.666: I/Adreno200-EGL(24175): Reconstruct Branch: AU_LINUX_ANDROID_JB_2.5.04.02.02.040.400 + NOTHING
06-21 09:46:13.706: D/OpenGLRenderer(24175): Enabling debug mode 0
06-21 09:46:24.217: D/AndroidRuntime(24175): Shutting down VM
06-21 09:46:24.217: W/dalvikvm(24175): threadid=1: thread exiting with uncaught exception (group=0x40c12ae0)
06-21 09:46:24.217: E/AndroidRuntime(24175): FATAL EXCEPTION: main
06-21 09:46:24.217: E/AndroidRuntime(24175): java.lang.IllegalStateException: Could not execute method of the activity
06-21 09:46:24.217: E/AndroidRuntime(24175): at android.view.View$1.onClick(View.java:3673)
06-21 09:46:24.217: E/AndroidRuntime(24175): at android.view.View.performClick(View.java:4278)
06-21 09:46:24.217: E/AndroidRuntime(24175): at android.view.View$PerformClick.run(View.java:17429)
06-21 09:46:24.217: E/AndroidRuntime(24175): at android.os.Handler.handleCallback(Handler.java:725)
06-21 09:46:24.217: E/AndroidRuntime(24175): at android.os.Handler.dispatchMessage(Handler.java:92)
06-21 09:46:24.217: E/AndroidRuntime(24175): at android.os.Looper.loop(Looper.java:137)
06-21 09:46:24.217: E/AndroidRuntime(24175): at android.app.ActivityThread.main(ActivityThread.java:5099)
06-21 09:46:24.217: E/AndroidRuntime(24175): at java.lang.reflect.Method.invokeNative(Native Method)
06-21 09:46:24.217: E/AndroidRuntime(24175): at java.lang.reflect.Method.invoke(Method.java:511)
06-21 09:46:24.217: E/AndroidRuntime(24175): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:803)
06-21 09:46:24.217: E/AndroidRuntime(24175): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:570)
06-21 09:46:24.217: E/AndroidRuntime(24175): at dalvik.system.NativeStart.main(Native Method)
06-21 09:46:24.217: E/AndroidRuntime(24175): Caused by: java.lang.reflect.InvocationTargetException
06-21 09:46:24.217: E/AndroidRuntime(24175): at java.lang.reflect.Method.invokeNative(Native Method)
06-21 09:46:24.217: E/AndroidRuntime(24175): at java.lang.reflect.Method.invoke(Method.java:511)
06-21 09:46:24.217: E/AndroidRuntime(24175): at android.view.View$1.onClick(View.java:3668)
06-21 09:46:24.217: E/AndroidRuntime(24175): ... 11 more
06-21 09:46:24.217: E/AndroidRuntime(24175): Caused by: java.lang.NullPointerException
06-21 09:46:24.217: E/AndroidRuntime(24175): at com.example.bucketlist.MainActivity.colorCorrecton(MainActivity.java:47)
06-21 09:46:24.217: E/AndroidRuntime(24175): at com.example.bucketlist.MainActivity.enterItem(MainActivity.java:204)
06-21 09:46:24.217: E/AndroidRuntime(24175): ... 14 more
06-21 09:46:26.069: I/Process(24175): Sending signal. PID: 24175 SIG: 9