Android 游标返回 null
Android Cursor returning null
我想知道是否有人可以帮助我。
我将在我的应用程序中使用 Sqlite3，但我以前从未使用过它，所以我想创建一个单独的项目来测试它，以确保我把它记下来。
我已经 运行 解决了这个错误，我在其中将一些文本值插入到单个列 table 中，这似乎没问题。在我查询 table 中的所有名称并通过光标移动以获取信息后出现问题。
我对此进行测试的方法是使用几个 TextView 和一个 Button。按下按钮时，TextView 会将其文本设置为光标第一个位置的值，然后 moveToNext() 将被调用，下一个 TextView 将更新，等等。
第一个 TextView 始终正确更新，但是当我在第一次调用 moveToNext() 后尝试设置下一个时，我得到一个空异常。
有没有办法在调试器中查看游标的内容？我似乎无法弄清楚。
有什么想法吗？这是代码：
MainActivity.java
package com.firsttread.anthony.databasetest;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
import com.firsttread.anthony.databasetest.DBContract.DBInfo;
public class MainActivity extends AppCompatActivity {
private Button testButton;
private TextView text1, text2, text3, text4;
private SQLiteDatabase db;
private DatabaseHelper DBHelper;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
testButton = (Button) findViewById(R.id.button);
text1 = (TextView) findViewById(R.id.textView);
text1 = (TextView) findViewById(R.id.textView2);
text1 = (TextView) findViewById(R.id.textView3);
text1 = (TextView) findViewById(R.id.textView4);
DBHelper = DatabaseHelper.getInstance(this);
db = DBHelper.getWritableDatabase();
Log.d("MainActivity", "getWritable successful");
ContentValues sessionValues1 = new ContentValues();
sessionValues1.put(DBInfo.COLUMN_SESSION_NAME, "Sleep");
ContentValues sessionValues2 = new ContentValues();
sessionValues2.put(DBInfo.COLUMN_SESSION_NAME, "Work");
ContentValues sessionValues3 = new ContentValues();
sessionValues3.put(DBInfo.COLUMN_SESSION_NAME, "Reading");
ContentValues sessionValues4 = new ContentValues();
sessionValues4.put(DBInfo.COLUMN_SESSION_NAME, "Walking");
long newRowId1, newRowId2, newRowId3, newRowId4;
//newRowId1 = db.insert(DBInfo.TABLE_SESSIONS, null, sessionValues1);
//newRowId2 = db.insert(DBInfo.TABLE_SESSIONS, null, sessionValues2);
//newRowId3 = db.insert(DBInfo.TABLE_SESSIONS, null, sessionValues3);
//newRowId4 = db.insert(DBInfo.TABLE_SESSIONS, null, sessionValues4);
String[] columns = {DBInfo.COLUMN_SESSION_NAME};
//DBHelper.deleteDB(db);
final Cursor c = db.query(
DBInfo.TABLE_SESSIONS,
columns,
null,
null,
null,
null,
null,
null
);
testButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
c.moveToFirst();
text1.setText(c.getString(c.getColumnIndex(DBInfo.COLUMN_SESSION_NAME)));
c.moveToNext();
text2.setText(c.getString(c.getColumnIndex(DBInfo.COLUMN_SESSION_NAME)));
c.moveToNext();
text3.setText(c.getString(c.getColumnIndex(DBInfo.COLUMN_SESSION_NAME)));
c.moveToNext();
text4.setText(c.getString(c.getColumnIndex(DBInfo.COLUMN_SESSION_NAME)));
}
});
}
@Override
protected void onStop() {
super.onStop();
db.close();
}
}
DataBaseHelper.java
package com.firsttread.anthony.databasetest;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
import com.firsttread.anthony.databasetest.DBContract.DBInfo;
public class DatabaseHelper extends SQLiteOpenHelper {
private static final String DATABASE_NAME = "SoundScope.db";
private static final int DATABASE_VERSION = 1;
private static final String SQL_CREATE_TABLES =
"CREATE TABLE " + DBInfo.TABLE_SESSIONS + " (" +
DBInfo.COLUMN_SESSION_NAME + " TEXT NOT NULL PRIMARY KEY);" +
"CREATE TABLE " + DBInfo.TABLE_SOUND_INFO + " (" +
DBInfo._ID + " INTEGER PRIMARY KEY, " +
DBInfo.COLUMN_SESSION_NAME + " TEXT NOT NULL, " +
DBInfo.COLUMN_SOUND + " TEXT NOT NULL, " +
DBInfo.COLUMN_VOLUME + " REAL NOT NULL); " +
"CREATE TABLE " + DBInfo.TABLE_SOUNDS + " (" +
DBInfo.COLUMN_SOUND_NAME + " TEXT NOT NULL PRIMARY KEY, " +
DBInfo.COLUMN_RAW + " INTEGER NOT NULL, " +
DBInfo.COLUMN_DRAWABLE + " INTEGER NOT NULL);" ;
private static final String SQL_DELETE_TABLES =
"DROP TABLE IF EXISTS " + DBInfo.TABLE_SOUNDS + ";" +
"DROP TABLE IF EXISTS " + DBInfo.TABLE_SOUND_INFO + ";" +
"DROP TABLE IF EXISTS " + DBInfo.TABLE_SESSIONS + ";" ;
private static DatabaseHelper mInstance;
public static synchronized DatabaseHelper getInstance(Context context){
if(mInstance == null){
mInstance = new DatabaseHelper(context.getApplicationContext());
Log.d("DatabaseHelper","DatabaseHelper instance successful");
}
return mInstance;
}
//private to ensure singleton
private DatabaseHelper(Context context){
super(context,DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(SQL_CREATE_TABLES);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
public void deleteDB(SQLiteDatabase db){
db.delete(DBInfo.TABLE_SESSIONS,null,null);
//db.delete(DBInfo.TABLE_SOUND_INFO,null,null);
//db.delete(DBInfo.TABLE_SOUNDS,null,null);
db.execSQL(SQL_DELETE_TABLES);
}
}
DBContract.java
package com.firsttread.anthony.databasetest;
import android.provider.BaseColumns;
public final class DBContract {
public DBContract(){}
public static abstract class DBInfo implements BaseColumns{
/*
*
* database schema
*
* */
//sessions table
public static final String TABLE_SESSIONS = "sessions";
public static final String COLUMN_SESSION_NAME = "name";
//sound_info
//uses BaseColumns _ID
public static final String TABLE_SOUND_INFO = "sound_info";
public static final String COLUMN_SESSION = "session";
public static final String COLUMN_SOUND = "sound";
public static final String COLUMN_VOLUME = "volume";
//soundS
public static final String TABLE_SOUNDS = "sounds";
public static final String COLUMN_SOUND_NAME = "name";
public static final String COLUMN_RAW = "raw";
public static final String COLUMN_DRAWABLE = "drawable";
}
}
以及错误的堆栈跟踪：
01-21 11:17:12.319 9149-9149/? E/Zygote: MountEmulatedStorage()
01-21 11:17:12.319 9149-9149/? E/Zygote: v2
01-21 11:17:12.319 9149-9149/? I/libpersona: KNOX_SDCARD checking this for 10075
01-21 11:17:12.319 9149-9149/? I/libpersona: KNOX_SDCARD not a persona
01-21 11:17:12.319 9149-9149/? I/SELinux: Function: selinux_compare_spd_ram, SPD-policy is existed. and_ver=SEPF_SAMSUNG-SM-N910A_5.1.1 ver=38
01-21 11:17:12.319 9149-9149/? I/SELinux: Function: selinux_compare_spd_ram , priority [1] , priority version is VE=SEPF_SAMSUNG-SM-N910A_5.1.1_0038
01-21 11:17:12.319 9149-9149/? E/Zygote: accessInfo : 0
01-21 11:17:12.319 9149-9149/? E/SELinux: [DEBUG] get_category: variable seinfo: default sensitivity: NULL, cateogry: NULL
01-21 11:17:12.319 9149-9149/? I/art: Late-enabling -Xcheck:jni
01-21 11:17:12.359 9149-9149/? D/TimaKeyStoreProvider: TimaSignature is unavailable
01-21 11:17:12.359 9149-9149/? D/ActivityThread: Added TimaKeyStore provider
01-21 11:17:12.449 9149-9149/com.firsttread.anthony.databasetest D/SecWifiDisplayUtil: Metadata value : none
01-21 11:17:12.489 9149-9149/com.firsttread.anthony.databasetest D/PhoneWindow: *FMB* installDecor mIsFloating : false
01-21 11:17:12.489 9149-9149/com.firsttread.anthony.databasetest D/PhoneWindow: *FMB* installDecor flags : -2139029248
01-21 11:17:12.549 9149-9149/com.firsttread.anthony.databasetest D/DatabaseHelper: DatabaseHelper instance successful
01-21 11:17:12.559 9149-9149/com.firsttread.anthony.databasetest D/MainActivity: getWritable successful
01-21 11:17:12.569 9149-9196/com.firsttread.anthony.databasetest D/OpenGLRenderer: Use EGL_SWAP_BEHAVIOR_PRESERVED: true
01-21 11:17:12.579 9149-9149/com.firsttread.anthony.databasetest D/PhoneWindow: *FMB* isFloatingMenuEnabled mFloatingMenuBtn : null
01-21 11:17:12.579 9149-9149/com.firsttread.anthony.databasetest D/PhoneWindow: *FMB* isFloatingMenuEnabled return false
01-21 11:17:12.599 9149-9149/com.firsttread.anthony.databasetest D/SRIB_DCS: log_dcs ThreadedRenderer::initialize entered!
01-21 11:17:12.609 9149-9196/com.firsttread.anthony.databasetest I/Adreno: EGLInit: QTI Build: 07/16/15, 126f54a, If3804f16ae
01-21 11:17:12.619 9149-9196/com.firsttread.anthony.databasetest I/OpenGLRenderer: Initialized EGL, version 1.4
01-21 11:17:12.629 9149-9196/com.firsttread.anthony.databasetest D/OpenGLRenderer: Get maximum texture size. GL_MAX_TEXTURE_SIZE is 16384
01-21 11:17:12.629 9149-9196/com.firsttread.anthony.databasetest D/OpenGLRenderer: Enabling debug mode 0
01-21 11:17:12.699 9149-9149/com.firsttread.anthony.databasetest I/Timeline: Timeline: Activity_idle id: android.os.BinderProxy@1f878246 time:177267508
01-21 11:17:15.329 9149-9149/com.firsttread.anthony.databasetest D/ViewRootImpl: ViewPostImeInputStage ACTION_DOWN
01-21 11:17:15.429 9149-9149/com.firsttread.anthony.databasetest D/AndroidRuntime: Shutting down VM
01-21 11:17:15.429 9149-9149/com.firsttread.anthony.databasetest E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.firsttread.anthony.databasetest, PID: 9149
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
at com.firsttread.anthony.databasetest.MainActivity.onClick(MainActivity.java:87)
at android.view.View.performClick(View.java:5242)
at android.widget.TextView.performClick(TextView.java:10530)
at android.view.View$PerformClick.run(View.java:21185)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:145)
at android.app.ActivityThread.main(ActivityThread.java:6872)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1404)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1199)
谢谢。
由于 findViewById()
的问题，您获得了 NPE
text1 = (TextView) findViewById(R.id.textView);
text1 = (TextView) findViewById(R.id.textView2);
text1 = (TextView) findViewById(R.id.textView3);
text1 = (TextView) findViewById(R.id.textView4);
您仅分配给 text1，然后尝试对其他分配 setText（text2、text3、text4），这为空值。
我想知道是否有人可以帮助我。
我将在我的应用程序中使用 Sqlite3，但我以前从未使用过它，所以我想创建一个单独的项目来测试它，以确保我把它记下来。
我已经 运行 解决了这个错误，我在其中将一些文本值插入到单个列 table 中，这似乎没问题。在我查询 table 中的所有名称并通过光标移动以获取信息后出现问题。
我对此进行测试的方法是使用几个 TextView 和一个 Button。按下按钮时，TextView 会将其文本设置为光标第一个位置的值，然后 moveToNext() 将被调用，下一个 TextView 将更新，等等。
第一个 TextView 始终正确更新，但是当我在第一次调用 moveToNext() 后尝试设置下一个时，我得到一个空异常。
有没有办法在调试器中查看游标的内容？我似乎无法弄清楚。
有什么想法吗？这是代码：
MainActivity.java
package com.firsttread.anthony.databasetest;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
import com.firsttread.anthony.databasetest.DBContract.DBInfo;
public class MainActivity extends AppCompatActivity {
private Button testButton;
private TextView text1, text2, text3, text4;
private SQLiteDatabase db;
private DatabaseHelper DBHelper;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
testButton = (Button) findViewById(R.id.button);
text1 = (TextView) findViewById(R.id.textView);
text1 = (TextView) findViewById(R.id.textView2);
text1 = (TextView) findViewById(R.id.textView3);
text1 = (TextView) findViewById(R.id.textView4);
DBHelper = DatabaseHelper.getInstance(this);
db = DBHelper.getWritableDatabase();
Log.d("MainActivity", "getWritable successful");
ContentValues sessionValues1 = new ContentValues();
sessionValues1.put(DBInfo.COLUMN_SESSION_NAME, "Sleep");
ContentValues sessionValues2 = new ContentValues();
sessionValues2.put(DBInfo.COLUMN_SESSION_NAME, "Work");
ContentValues sessionValues3 = new ContentValues();
sessionValues3.put(DBInfo.COLUMN_SESSION_NAME, "Reading");
ContentValues sessionValues4 = new ContentValues();
sessionValues4.put(DBInfo.COLUMN_SESSION_NAME, "Walking");
long newRowId1, newRowId2, newRowId3, newRowId4;
//newRowId1 = db.insert(DBInfo.TABLE_SESSIONS, null, sessionValues1);
//newRowId2 = db.insert(DBInfo.TABLE_SESSIONS, null, sessionValues2);
//newRowId3 = db.insert(DBInfo.TABLE_SESSIONS, null, sessionValues3);
//newRowId4 = db.insert(DBInfo.TABLE_SESSIONS, null, sessionValues4);
String[] columns = {DBInfo.COLUMN_SESSION_NAME};
//DBHelper.deleteDB(db);
final Cursor c = db.query(
DBInfo.TABLE_SESSIONS,
columns,
null,
null,
null,
null,
null,
null
);
testButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
c.moveToFirst();
text1.setText(c.getString(c.getColumnIndex(DBInfo.COLUMN_SESSION_NAME)));
c.moveToNext();
text2.setText(c.getString(c.getColumnIndex(DBInfo.COLUMN_SESSION_NAME)));
c.moveToNext();
text3.setText(c.getString(c.getColumnIndex(DBInfo.COLUMN_SESSION_NAME)));
c.moveToNext();
text4.setText(c.getString(c.getColumnIndex(DBInfo.COLUMN_SESSION_NAME)));
}
});
}
@Override
protected void onStop() {
super.onStop();
db.close();
}
}
DataBaseHelper.java
package com.firsttread.anthony.databasetest;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
import com.firsttread.anthony.databasetest.DBContract.DBInfo;
public class DatabaseHelper extends SQLiteOpenHelper {
private static final String DATABASE_NAME = "SoundScope.db";
private static final int DATABASE_VERSION = 1;
private static final String SQL_CREATE_TABLES =
"CREATE TABLE " + DBInfo.TABLE_SESSIONS + " (" +
DBInfo.COLUMN_SESSION_NAME + " TEXT NOT NULL PRIMARY KEY);" +
"CREATE TABLE " + DBInfo.TABLE_SOUND_INFO + " (" +
DBInfo._ID + " INTEGER PRIMARY KEY, " +
DBInfo.COLUMN_SESSION_NAME + " TEXT NOT NULL, " +
DBInfo.COLUMN_SOUND + " TEXT NOT NULL, " +
DBInfo.COLUMN_VOLUME + " REAL NOT NULL); " +
"CREATE TABLE " + DBInfo.TABLE_SOUNDS + " (" +
DBInfo.COLUMN_SOUND_NAME + " TEXT NOT NULL PRIMARY KEY, " +
DBInfo.COLUMN_RAW + " INTEGER NOT NULL, " +
DBInfo.COLUMN_DRAWABLE + " INTEGER NOT NULL);" ;
private static final String SQL_DELETE_TABLES =
"DROP TABLE IF EXISTS " + DBInfo.TABLE_SOUNDS + ";" +
"DROP TABLE IF EXISTS " + DBInfo.TABLE_SOUND_INFO + ";" +
"DROP TABLE IF EXISTS " + DBInfo.TABLE_SESSIONS + ";" ;
private static DatabaseHelper mInstance;
public static synchronized DatabaseHelper getInstance(Context context){
if(mInstance == null){
mInstance = new DatabaseHelper(context.getApplicationContext());
Log.d("DatabaseHelper","DatabaseHelper instance successful");
}
return mInstance;
}
//private to ensure singleton
private DatabaseHelper(Context context){
super(context,DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(SQL_CREATE_TABLES);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
public void deleteDB(SQLiteDatabase db){
db.delete(DBInfo.TABLE_SESSIONS,null,null);
//db.delete(DBInfo.TABLE_SOUND_INFO,null,null);
//db.delete(DBInfo.TABLE_SOUNDS,null,null);
db.execSQL(SQL_DELETE_TABLES);
}
}
DBContract.java
package com.firsttread.anthony.databasetest;
import android.provider.BaseColumns;
public final class DBContract {
public DBContract(){}
public static abstract class DBInfo implements BaseColumns{
/*
*
* database schema
*
* */
//sessions table
public static final String TABLE_SESSIONS = "sessions";
public static final String COLUMN_SESSION_NAME = "name";
//sound_info
//uses BaseColumns _ID
public static final String TABLE_SOUND_INFO = "sound_info";
public static final String COLUMN_SESSION = "session";
public static final String COLUMN_SOUND = "sound";
public static final String COLUMN_VOLUME = "volume";
//soundS
public static final String TABLE_SOUNDS = "sounds";
public static final String COLUMN_SOUND_NAME = "name";
public static final String COLUMN_RAW = "raw";
public static final String COLUMN_DRAWABLE = "drawable";
}
}
以及错误的堆栈跟踪：
01-21 11:17:12.319 9149-9149/? E/Zygote: MountEmulatedStorage()
01-21 11:17:12.319 9149-9149/? E/Zygote: v2
01-21 11:17:12.319 9149-9149/? I/libpersona: KNOX_SDCARD checking this for 10075
01-21 11:17:12.319 9149-9149/? I/libpersona: KNOX_SDCARD not a persona
01-21 11:17:12.319 9149-9149/? I/SELinux: Function: selinux_compare_spd_ram, SPD-policy is existed. and_ver=SEPF_SAMSUNG-SM-N910A_5.1.1 ver=38
01-21 11:17:12.319 9149-9149/? I/SELinux: Function: selinux_compare_spd_ram , priority [1] , priority version is VE=SEPF_SAMSUNG-SM-N910A_5.1.1_0038
01-21 11:17:12.319 9149-9149/? E/Zygote: accessInfo : 0
01-21 11:17:12.319 9149-9149/? E/SELinux: [DEBUG] get_category: variable seinfo: default sensitivity: NULL, cateogry: NULL
01-21 11:17:12.319 9149-9149/? I/art: Late-enabling -Xcheck:jni
01-21 11:17:12.359 9149-9149/? D/TimaKeyStoreProvider: TimaSignature is unavailable
01-21 11:17:12.359 9149-9149/? D/ActivityThread: Added TimaKeyStore provider
01-21 11:17:12.449 9149-9149/com.firsttread.anthony.databasetest D/SecWifiDisplayUtil: Metadata value : none
01-21 11:17:12.489 9149-9149/com.firsttread.anthony.databasetest D/PhoneWindow: *FMB* installDecor mIsFloating : false
01-21 11:17:12.489 9149-9149/com.firsttread.anthony.databasetest D/PhoneWindow: *FMB* installDecor flags : -2139029248
01-21 11:17:12.549 9149-9149/com.firsttread.anthony.databasetest D/DatabaseHelper: DatabaseHelper instance successful
01-21 11:17:12.559 9149-9149/com.firsttread.anthony.databasetest D/MainActivity: getWritable successful
01-21 11:17:12.569 9149-9196/com.firsttread.anthony.databasetest D/OpenGLRenderer: Use EGL_SWAP_BEHAVIOR_PRESERVED: true
01-21 11:17:12.579 9149-9149/com.firsttread.anthony.databasetest D/PhoneWindow: *FMB* isFloatingMenuEnabled mFloatingMenuBtn : null
01-21 11:17:12.579 9149-9149/com.firsttread.anthony.databasetest D/PhoneWindow: *FMB* isFloatingMenuEnabled return false
01-21 11:17:12.599 9149-9149/com.firsttread.anthony.databasetest D/SRIB_DCS: log_dcs ThreadedRenderer::initialize entered!
01-21 11:17:12.609 9149-9196/com.firsttread.anthony.databasetest I/Adreno: EGLInit: QTI Build: 07/16/15, 126f54a, If3804f16ae
01-21 11:17:12.619 9149-9196/com.firsttread.anthony.databasetest I/OpenGLRenderer: Initialized EGL, version 1.4
01-21 11:17:12.629 9149-9196/com.firsttread.anthony.databasetest D/OpenGLRenderer: Get maximum texture size. GL_MAX_TEXTURE_SIZE is 16384
01-21 11:17:12.629 9149-9196/com.firsttread.anthony.databasetest D/OpenGLRenderer: Enabling debug mode 0
01-21 11:17:12.699 9149-9149/com.firsttread.anthony.databasetest I/Timeline: Timeline: Activity_idle id: android.os.BinderProxy@1f878246 time:177267508
01-21 11:17:15.329 9149-9149/com.firsttread.anthony.databasetest D/ViewRootImpl: ViewPostImeInputStage ACTION_DOWN
01-21 11:17:15.429 9149-9149/com.firsttread.anthony.databasetest D/AndroidRuntime: Shutting down VM
01-21 11:17:15.429 9149-9149/com.firsttread.anthony.databasetest E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.firsttread.anthony.databasetest, PID: 9149
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
at com.firsttread.anthony.databasetest.MainActivity.onClick(MainActivity.java:87)
at android.view.View.performClick(View.java:5242)
at android.widget.TextView.performClick(TextView.java:10530)
at android.view.View$PerformClick.run(View.java:21185)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:145)
at android.app.ActivityThread.main(ActivityThread.java:6872)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1404)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1199)
谢谢。
由于 findViewById()
text1 = (TextView) findViewById(R.id.textView);
text1 = (TextView) findViewById(R.id.textView2);
text1 = (TextView) findViewById(R.id.textView3);
text1 = (TextView) findViewById(R.id.textView4);
您仅分配给 text1，然后尝试对其他分配 setText（text2、text3、text4），这为空值。