java - 如何在 Android 的 ListView 中显示 SQLite 数据库中的多个数据
问题描述
我是Android开发的新手。
我不知道如何让 Android Studio 只获取我的 SQLite 数据库中的内容并将其内容粘贴到列表视图中。我认为在记录输出后会有一种简单的方法,但可以在 ListView 中显示数据库中的所有内容,但它似乎以不同的方式进行。
public class MainActivity extends AppCompatActivity {
EditText nameEditText;
EditText phoneEditText;
ListView updateListView;
SQLiteDatabase sqLiteDatabase;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
nameEditText = findViewById(R.id.nameEditText);
phoneEditText = findViewById(R.id.phoneEditText);
updateListView = findViewById(R.id.updatedListView);
sqLiteDatabase = this.openOrCreateDatabase("Contact", MODE_PRIVATE, null);
sqLiteDatabase.execSQL("CREATE TABLE IF NOT EXISTS users(name VARCHAR, phone INT(11),id INTEGER PRIMARY KEY)");
}
public void OnClick(View view) {
if (nameEditText.equals("") || phoneEditText.equals("")) {
Toast.makeText(this, "Fields shouldn't be empty", Toast.LENGTH_SHORT).show();
} else {
sqLiteDatabase.execSQL("INSERT INTO users(name, phone) VALUES('" + nameEditText.getText().toString() + "','" + phoneEditText.getText().toString() + "')");
Cursor c = sqLiteDatabase.rawQuery("SELECT * FROM users", null);
int nameIndex = c.getColumnIndex("name");
int phoneIndex = c.getColumnIndex("phone");
int idIndex = c.getColumnIndex("id");
if (c != null && c.getCount() > 0) {
c.moveToFirst();
for (int i = 0; i < c.getCount(); i++) {
String str = c.getString(0);
String UpdatedList = (c.getString(nameIndex));
String phonelist = (c.getString(phoneIndex));
String list = (UpdatedList+phonelist);
ArrayList<String> arrayList = new ArrayList<String>(Integer.parseInt(list));
ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(MainActivity.this,android.R.layout.simple_list_item_1,arrayList);
updateListView.setAdapter(arrayAdapter);
Log.i("User Name", c.getString(nameIndex));
Log.i("userResults - age", Integer.toString(c.getInt(phoneIndex)));
Log.i("userResults - id", Integer.toString(c.getInt(idIndex)));
c.moveToNext();
}
}
}
}
}
我的日志
2020-01-22 20:22:48.353 28783-28783/? D/AndroidRuntime: Shutting down VM
2020-01-22 20:22:48.357 28783-28783/? E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.mysqlapp, PID: 28783
java.lang.IllegalStateException: Could not execute method for android:onClick
at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:390)
at android.view.View.performClick(View.java:6669)
at android.view.View.performClickInternal(View.java:6638)
at android.view.View.access$3100(View.java:789)
at android.view.View$PerformClick.run(View.java:26145)
at android.os.Handler.handleCallback(Handler.java:873)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6898)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:537)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:385)
at android.view.View.performClick(View.java:6669)
at android.view.View.performClickInternal(View.java:6638)
at android.view.View.access$3100(View.java:789)
at android.view.View$PerformClick.run(View.java:26145)
at android.os.Handler.handleCallback(Handler.java:873)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6898)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:537)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
Caused by: java.lang.NumberFormatException: For input string: ""
at java.lang.Integer.parseInt(Integer.java:627)
at java.lang.Integer.parseInt(Integer.java:650)
at com.example.mysqlapp.MainActivity.OnClick(MainActivity.java:65)
解决方案
在从 sql 声明整个 arrayList 之后,在 for 循环之外调用 setAdapter 方法
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