当前位置：首页 > news >正文

Android : ViewModel+LiveData observe观察数据改变内容简单应用

news 来源：原创 2024/5/17 1:13:56

observe观察数据改变内容

1.导包

// 使用androidx版本库implementation 'androidx.lifecycle:lifecycle-extensions:2.1.0-alpha03'// 或者，使用support版本库implementation 'android.arch.lifecycle:extensions:1.1.1'

2.继承ViewModel

package com.example.mylivedata;import androidx.lifecycle.MutableLiveData;
import androidx.lifecycle.ViewModel;//需要改变的数据
public class MyViewModel extends ViewModel {private MutableLiveData<Integer>  data;public MutableLiveData<Integer> getData() {if(data == null){data = new MutableLiveData<>();data.setValue(0);}return data;}public void addNumberData(int num){data.setValue(data.getValue() + num);}
}

3.使用

package com.example.mylivedata;import android.os.Bundle;
import android.view.View;
import android.widget.ImageView;
import android.widget.TextView;import androidx.appcompat.app.AppCompatActivity;
import androidx.lifecycle.Observer;
import androidx.lifecycle.ViewModelProviders;public class MainActivity extends AppCompatActivity {private TextView textView;private ImageView imgZan,imgCai;private MyViewModel myViewModel;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);textView = findViewById(R.id.tv_content);imgZan = findViewById(R.id.img_zan);imgCai =findViewById(R.id.img_cai);myViewModel= ViewModelProviders.of(this).get(MyViewModel.class);//观察自己myViewModel.getData().observe(this, new Observer<Integer>() {@Overridepublic void onChanged(Integer integer) {//内容发生改变textView.setText(String.valueOf(integer));}});//绑定事件imgZan.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {myViewModle.addNumberData(1);}});imgCai.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {myViewModle.addNumberData(-1);}});}
}