Question

我从 lifecycle 体系结构库中添加了一个 ViewModel 类。但这在我的代码中不起作用。我做错了什么。我是android的ViewModel Arch组件的新手。

这是我的代码：

等级：

dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation 'com.android.support:appcompat-v7:28.0.0-rc01'
implementation 'com.android.support.constraint:constraint-layout:1.1.2'
testImplementation 'junit:junit:4.12'
androidTestImplementation 'com.android.support.test:runner:1.0.2'
androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'

// ViewModel and LiveData
implementation "android.arch.lifecycle:extensions:1.1.1"

}

ViewModel：

import android.arch.lifecycle.MutableLiveData;
import android.arch.lifecycle.ViewModel;

public class NameViewModel extends ViewModel {

// Create a LiveData with a String
private MutableLiveData<String> mCurrentName;

public MutableLiveData<String> getmCurrentName() {
    if (mCurrentName == null) {
        mCurrentName = new MutableLiveData<>();
    }
    return mCurrentName;
}

}

MainActivity.java

import android.arch.lifecycle.Observer;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.text.Editable;
import android.text.TextWatcher;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

private NameViewModel nameViewModel;

private TextView lblText;
private EditText txtValue;

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

    lblText = findViewById(R.id.textview);
    txtValue = findViewById(R.id.editText);

    final Observer<String> nameObserver = new Observer<String>() {
        @Override
        public void onChanged(@Nullable String data) {

            lblText.setText(data);

        }
    };

    nameViewModel.getmCurrentName().observe(this, nameObserver);

    txtValue.addTextChangedListener(new TextWatcher() {
        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int after) {

        }

        @Override
        public void onTextChanged(CharSequence value, int start, int before, int count) {
            nameViewModel.getmCurrentName().setValue(value.toString());
        }

        @Override
        public void afterTextChanged(Editable s) {

        }
    });

  }
}

我错过了必要的东西吗？

任何帮助将不胜感激。非常感谢。

Answer 1

将其放入您的pd.DataFrame(list(itertools.product(set(x.user), y)), columns=['user', 'movie'])\ .merge(x, how='outer') Out[76]: user movie rating 0 1 100 1.0 1 1 200 4.0 2 1 300 3.0 3 1 400 NaN 4 2 100 5.0 5 2 200 3.0 6 2 300 NaN 7 2 400 NaN 8 3 100 NaN 9 3 200 NaN 10 3 300 2.0 11 3 400 NaN方法中

onCreate

并参考this和this链接以获取有关nameViewModel = ViewModelProviders.of(this, null).get(NameViewModel.class);的更多信息

即使添加了ViewModel，配置也会发生变化：Android体系结构组件

1 个答案: