(Anroid Studio)用简单代码实现BMI计算器并且将应用安装到手机上

找到content_main.xml:

找到MainActivity类：里面需要注意编写的每一个组件的id需要一致。

package com.example.myapplication777;

import android.icu.text.Edits;
import android.os.Bundle;

import com.google.android.material.snackbar.Snackbar;

import androidx.appcompat.app.AppCompatActivity;

import android.util.Log;
import android.view.View;

import androidx.navigation.NavController;
import androidx.navigation.Navigation;
import androidx.navigation.ui.AppBarConfiguration;
import androidx.navigation.ui.NavigationUI;

import com.example.myapplication777.databinding.ActivityMainBinding;

import android.view.Menu;
import android.view.MenuItem;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    private AppBarConfiguration appBarConfiguration;
    private ActivityMainBinding binding;


    //计算
    public  float height=0f;
    public  float weight=0f;
    public  float result=0f;
    //输入框的属性
    EditText editText1=null;
    EditText editText2=null;
    TextView  textView =null;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        binding = ActivityMainBinding.inflate(getLayoutInflater());
        setContentView(binding.getRoot());
        setSupportActionBar(binding.toolbar);
        //实例化
        //身高体重
        editText1=(EditText)findViewById(R.id.editTextTextPersonName);
        editText2=(EditText)findViewById(R.id.editTextTextPersonName2);
        //显示结果
        textView=(TextView)findViewById(R.id.textView4);




        NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment_content_main);
        appBarConfiguration = new AppBarConfiguration.Builder(navController.getGraph()).build();
        NavigationUI.setupActionBarWithNavController(this, navController, appBarConfiguration);

        binding.fab.setonClickListener(new View.onClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });
    }
//计算
    public  void onClick(View view){
        Log.d("TAG","--------点击了计算按钮-------");
        height= Float.parseFloat(editText1.getText().toString());
        height=height/100f;
        weight= Float.parseFloat(editText2.getText().toString());
        result=weight/(height*height);
        textView.setText("您的BMI值为："+result);
    }
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    @Override
    public boolean onSupportNavigateUp() {
        NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment_content_main);
        return NavigationUI.navigateUp(navController, appBarConfiguration)
                || super.onSupportNavigateUp();
    }
}

如果因为gradle版本的问题可以看前面一期。

 进行安装即可，出现安卓手机版本问题需要调一下sdk。最后手机上安装成功。