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私はアンドロイド開発の新人です、ここではsqliteを使って簡単なデータベースアプリケーションを作成しようとしています ユーザーがそれを検索する選択したときに私は何をしようとしていることは、IDとIDが一致する対応するデータが要求されますされている特定のデータでのEditTextのフィールドを置き換える必要がありヌルオブジェクト参照で仮想メソッド 'void android.widget.EditText.setText（java.lang.CharSequence）'を呼び出そうとしています
ActivityMain.xml
<?xml version="1.0" encoding="utf-8"?>
<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"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.ashish.project.MainActivity">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="Personal Details"
android:id="@+id/textView"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:gravity="center" />
<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fillViewport="true">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<GridLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/gridLayout"
android:layout_centerVertical="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true">
<LinearLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="50dp"
android:layout_row="0"
android:layout_column="0">
<EditText
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:inputType="textPersonName"
android:ems="10"
android:id="@+id/editText"
android:layout_weight="1"
android:hint="First Name" />
<EditText
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:inputType="textPersonName"
android:ems="10"
android:id="@+id/editText_LastName"
android:layout_weight="1"
android:hint="Last Name" />
</LinearLayout>
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:inputType="number"
android:ems="10"
android:id="@+id/editText_number"
android:layout_row="1"
android:layout_column="0"
android:hint="Contact Number" />
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:inputType="textEmailAddress"
android:ems="10"
android:id="@+id/editText_email"
android:layout_row="2"
android:layout_column="0"
android:hint="E-mail" />
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_row="3"
android:layout_column="0">
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Submit Details"
android:id="@+id/Button_Submit"
android:layout_weight="1"
android:layout_row="4"
android:layout_column="0" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Show Details"
android:id="@+id/button_Show_Details"
android:layout_gravity="right"
android:layout_weight="1"
android:layout_row="5"
android:layout_column="0"
android:layout_alignParentTop="true"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/button_search"
android:layout_below="@id/Button_Submit"
android:text="search"/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Clear Table"
android:id="@+id/button_clear"
android:gravity="left|center_horizontal"
android:layout_below="@+id/button_Show_Details"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true" />
</RelativeLayout>
</GridLayout>
<EditText
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:inputType="number"
android:ems="10"
android:id="@+id/editText_srch"
android:hint="Enter id to search"
android:layout_alignParentBottom="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="search"
android:id="@+id/button_show_id_result"
android:layout_alignParentBottom="true"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true" />
</RelativeLayout>
</LinearLayout>
</ScrollView>
</RelativeLayout>
MainActivity .java
package com.example.ashish.project;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.view.inputmethod.InputMethodManager;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
Button button_submit,button_show_details,button_clear,button_search,button_show_id_result;
EditText firstName,lastName,number,email,editText_id_search;
String firstnameString,lastnameString,emailString,num;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button_submit=(Button)findViewById(R.id.Button_Submit);
button_show_id_result=(Button) findViewById(R.id.button_show_id_result);
editText_id_search=(EditText) findViewById(R.id.editText_srch);
button_show_details=(Button)findViewById(R.id.button_Show_Details);
firstName=(EditText)findViewById(R.id.editText);
button_search=(Button) findViewById(R.id.button_search);
button_clear=(Button)findViewById(R.id.button_clear);
lastName=(EditText)findViewById(R.id.editText_LastName);
number=(EditText)findViewById(R.id.editText_number);
email=(EditText)findViewById(R.id.editText_email);
editText_id_search.setVisibility(View.GONE);
button_show_id_result.setVisibility(View.GONE);
button_clear.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
DatabaseHelper db = new DatabaseHelper(getApplicationContext());
db.clear();
}
});
button_search.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
/*
*/
editText_id_search.setVisibility(View.VISIBLE);
button_show_id_result.setVisibility(View.VISIBLE);
button_show_id_result.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
String qry = editText_id_search.getText().toString();
DatabaseHelper db = new DatabaseHelper(getApplicationContext());
db.search(qry);
}
});
}
});
button_submit.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
firstnameString = firstName.getText().toString();
lastnameString=lastName.getText().toString();
num=number.getText().toString();
emailString=email.getText().toString();
DatabaseHelper db = new DatabaseHelper(getApplicationContext());
db.insertData(firstnameString,lastnameString,num,emailString);
Toast.makeText(MainActivity.this,"Record Updated",Toast.LENGTH_LONG).show();
InputMethodManager input = (InputMethodManager) getSystemService(INPUT_METHOD_SERVICE);
input.hideSoftInputFromWindow(email.getWindowToken(),0);
firstName.setText("");
lastName.setText("");
number.setText("");
email.setText("");
db.close();
}
});
button_show_details.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent i = new Intent(MainActivity.this,List_Result.class);
startActivity(i);
}
});
}
public void show(String string, String cString, String s, String string1) {
firstName.setText(string);
lastName.setText(cString);
number.setText(s);
email.setText(string1);
}
}
DatabaseHelper.java
package com.example.ashish.project;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import java.util.ArrayList;
/**
* Created by ashis on 7/21/2016.
*/
public class DatabaseHelper extends SQLiteOpenHelper {
private static int DATABASE_VERSION = 6;
private static String DATABSE_NAME="DATA";
private static String TABLE_NAME="PERSONAL_INFORMATION";
private static String COLLUMN_ID= "_ID";
private static String COLLUMN_FIRST_NAME="FIRST_NAME";
private static String COLLUMN_LAST_NAME="LAST_NAME";
private static String COLLUMN_NUMBER = "NUMBER";
private static String COLLUMN_EMAIL="EMAIL";
public DatabaseHelper(Context context)
{
super(context,DATABSE_NAME,null,DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase sqLiteDatabase) {
String CREATE_TABLE = "CREATE TABLE "+TABLE_NAME + "("
+ COLLUMN_ID +" INTEGER PRIMARY KEY, "
+ COLLUMN_FIRST_NAME + " TEXT, "
+ COLLUMN_LAST_NAME + " TEXT, "
+ COLLUMN_NUMBER + " TEXT , "
+ COLLUMN_EMAIL + " TEXT"+")";
sqLiteDatabase.execSQL(CREATE_TABLE);
}
@Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
sqLiteDatabase.execSQL("DROP TABLE IF EXISTS"+TABLE_NAME);
this.onCreate(sqLiteDatabase);
}
public void insertData(String firstnameString, String lastnameString, String num, String emailString) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(COLLUMN_FIRST_NAME,firstnameString);
values.put(COLLUMN_LAST_NAME,lastnameString);
values.put(COLLUMN_NUMBER,num);
values.put(COLLUMN_EMAIL,emailString);
db.insertOrThrow(TABLE_NAME,null,values);
db.close();
}
public ArrayList<String> readData() {
ArrayList<String> list = new ArrayList<>();
String readQry = "SELECT * FROM "+TABLE_NAME;
SQLiteDatabase db = this.getReadableDatabase();
Cursor c = db.rawQuery(readQry,null);
if (c.moveToFirst())
{
do {
list.add(c.getString(0)+ ": "+c.getString(1) +" "+ c.getString(2)+","+c.getString(3)+","+c.getString(4));
}while (c.moveToNext());
}
c.close();
db.close();
return list;
}
public void clear() {
SQLiteDatabase db= this.getWritableDatabase();
String clrqry = "DROP TABLE " + TABLE_NAME;
db.execSQL(clrqry);
this.onCreate(db);
}
public void search(String srch) {
SQLiteDatabase db = this.getReadableDatabase();
MainActivity obj = new MainActivity();
String sqlqry = "SELECT * FROM "+TABLE_NAME +" WHERE "+ COLLUMN_ID + " = ?";
Cursor c= db.rawQuery(sqlqry,new String[]{srch});
if (c.moveToFirst())
{
do {
obj.show(c.getString(1),c.getString(2),c.getString(3),c.getString(4));
}
while (c.moveToNext());
}
}
}
Activity_list.xml
<?xml version="1.0" encoding="utf-8"?>
<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"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.ashish.project.List_Result">
<ListView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/listView2"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:background="@android:color/darker_gray" />
</RelativeLayout>
私は
IDを入力した後、[検索]をクリックしようとすると、Activity_list.java ここpackage com.example.ashish.project;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import java.util.ArrayList;
public class List_Result extends AppCompatActivity {
ListView listview1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_list__result);
listview1=(ListView) findViewById(R.id.listView2);
loadlistviewData();
}
private void loadlistviewData() {
DatabaseHelper db = new DatabaseHelper(getApplicationContext());
ArrayList<String> list = db.readData();
ArrayAdapter<String> adapter = new ArrayAdapter<String>(getApplicationContext(),android.R.layout.simple_list_item_1,list);
adapter.setDropDownViewResource(android.R.layout.simple_list_item_1);
listview1.setAdapter(adapter);
}
}
はlogcatです
07-25 14:27:34.033 668-668/com.example.ashish.project W/System: ClassLoader referenced unknown path: /data/app/com.example.ashish.project-2/lib/arm
07-25 14:27:34.256 668-668/com.example.ashish.project W/art: Before Android 4.1, method android.graphics.PorterDuffColorFilter android.support.graphics.drawable.VectorDrawableCompat.updateTintFilter(android.graphics.PorterDuffColorFilter, android.content.res.ColorStateList, android.graphics.PorterDuff$Mode) would have incorrectly overridden the package-private method in android.graphics.drawable.Drawable
07-25 14:27:34.541 668-668/com.example.ashish.project D/android.widget.GridLayout: vertical constraints: y4-y0>=864, y4-y3<=192, y3-y2<=91, y2-y1<=91, y1-y0<=100 are inconsistent; permanently removing: y4-y3<=192.
07-25 14:27:39.235 668-668/com.example.ashish.project D/AndroidRuntime: Shutting down VM
07-25 14:27:39.236 668-668/com.example.ashish.project E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.ashish.project, PID: 668
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.EditText.setText(java.lang.CharSequence)' on a null object reference
at com.example.ashish.project.MainActivity.show(MainActivity.java:103)
at com.example.ashish.project.DatabaseHelper.search(DatabaseHelper.java:108)
at com.example.ashish.project.MainActivity$2$1.onClick(MainActivity.java:60)
at android.view.View.performClick(View.java:5201)
at android.view.View$PerformClick.run(View.java:21163)
at android.os.Handler.handleCallback(Handler.java:746)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5443)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:728)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
すべてのヘルプは、あなたがMainActivityの新しいインスタンスを作成することによって、ショー（）を呼び出す
'NullPointerExceptionが発生：試み仮想メソッド 'void android.widget.EditText.setText'を呼び出します。 –
あなたの 'button_submit' onclick？ –