Question

我在下面的代码中收到以下错误，我找不到解决方案，您能帮忙

代码：

   public class MainActivity extends AppCompatActivity {
private Button buttonGetir,buttonSil,buttonGuncelle,buttonKaydet;
private TextView textViewCikti;
private EditText editTextId,editTextAd,editTextTel;
static final String PROVIDER_NAME ="info.com.MyProvider";
static final String URL="content://"+PROVIDER_NAME+"/rehber";
static final Uri CONTENT_URI = Uri.parse(URL);
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    buttonGetir = findViewById(R.id.buttonGetir);
    buttonSil = findViewById(R.id.buttonSil);
    buttonGuncelle = findViewById(R.id.buttonGuncelle);
    buttonKaydet = findViewById(R.id.buttonKaydet);
    textViewCikti =findViewById(R.id.textViewCikti);
    editTextAd = findViewById(R.id.editTextAd);
    editTextId = findViewById(R.id.editTextId);
    editTextTel = findViewById(R.id.editTextTel);


    buttonKaydet.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            ContentValues values= new ContentValues();

            values.put("ad",editTextAd.getText().toString());
            values.put("tel",editTextTel.getText().toString());

            Uri uri = getContentResolver().insert(CONTENT_URI,values);
            Toast.makeText(MainActivity.this, "Rehber : "+uri.toString()+"Kayıt Edildi", Toast.LENGTH_SHORT).show();
        }
    });

    buttonGetir.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Cursor c = getContentResolver().query(CONTENT_URI,null,null,null,null);

            String result ="Rehber sonuç : ";

            while (c.moveToNext()){
                result =result + "\n"+c.getInt(c.getColumnIndex("id"))
                        +"--"+c.getString(c.getColumnIndex("ad"))
                        +"--"+c.getString(c.getColumnIndex("tel"));
            }
            textViewCikti.setText(result);
        }
    });

    buttonSil.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Uri uri = Uri.parse("content://info.com.MyProvider/rehber/"+editTextId.getText().toString());

            int count = getContentResolver().delete(uri,null,null);
        }
    });

    buttonGuncelle.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            ContentValues values= new ContentValues();

            values.put("ad",editTextAd.getText().toString());
            values.put("tel",editTextTel.getText().toString());

            Uri uri = Uri.parse("content://info.com.MyProvider/rehber/"+editTextId.getText().toString());

            int count = getContentResolver().update(uri,values,null,null);
        }
    });
}

}

E / ActivityThread：无法找到info.com.MyProvider的提供者信息。 D / AndroidRuntime：关闭VM E / AndroidRuntime：致命异常：main 流程：info.com，PID：3076 java.lang.NullPointerException：尝试在空对象引用上调用接口方法'boolean android.database.Cursor.moveToNext（）' 在info.com.MainActivity $ 2.onClick（MainActivity.java:58）在android.view.View.performClick（View.java:5609）在android.view.View $ PerformClick.run（View.java:22259）在android.os.Handler.handleCallback（Handler.java:751）在android.os.Handler.dispatchMessage（Handler.java:95）在android.os.Looper.loop（Looper.java:154）在android.app.ActivityThread.main（ActivityThread.java:6077）在java.lang.reflect.Method.invoke（本机方法）在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:865）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:755）

布尔android.database.cursor.movetonext（）在空对象引用上

0 个答案: