单击 Android 后退按钮时清除变量

Question

我有一个应用程序，我希望能够在其中单击按钮 A 并显示一组特定信息。然后单击后退按钮并单击按钮 B 并显示一组不同的信息。我已将测试 TextView 编码到 Drinks.java 文件中，以便通过确认正在传递的内容来开始该过程。目前，无论我先按下什么按钮，都会卡在变量中。因此，例如，如果我按下按钮 A，然后按下后退箭头并按下按钮 B，则按钮 A 仍显示在 textView 中。我尝试在点击侦听器中将字符串设为空，"clear them out"，但这是行不通的。有没有办法清除变量中的内容并重新分配其他内容？还是我的问题出在其他地方？

Bar.java

import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;

public class Bar extends Activity{
    String setBarTest = MainActivity.setBar;
    String barNameHolder, picHolder, barContactHolder, barPhoneHolder; 
    int imageInt, textInt1,textInt2, textInt3;
    TextView setBarName, setBarContact,setBarPhone;
    ImageView barPic;
    Button viewAll, beer, wine, mixedDrinks, other, getTaxi;
    static String setDrinkType = "";

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_bar);

        Button viewAll = (Button)findViewById(R.id.btnviewAll);
        Button beer = (Button)findViewById(R.id.btnBeer);
        Button wine = (Button)findViewById(R.id.btnWine);
        Button mixedDrinks = (Button)findViewById(R.id.btnMixedDrinks);
        Button other = (Button)findViewById(R.id.btnOther);
        Button getTaxi = (Button)findViewById(R.id.btnTaxi);

        barPic = (ImageView) findViewById(R.id.barPic);
        String picHolder = "drawable/"+setBarTest;      
        int imageInt = getResources().getIdentifier(picHolder, null, getPackageName());
        barPic.setImageResource(imageInt);

        setBarName = (TextView)findViewById(R.id.barName);
        String barNameHolder = "@string/"+setBarTest;
        int textInt1 = getResources().getIdentifier(barNameHolder, null, getPackageName());
        setBarName.setText(textInt1);

        setBarContact = (TextView)findViewById(R.id.barContact);
        String barContactHolder = "@string/"+setBarTest+"Contact";
        int textInt2 = getResources().getIdentifier(barContactHolder, null, getPackageName());
        setBarContact.setText(textInt2);

        setBarPhone = (TextView)findViewById(R.id.barPhone);
        String barPhoneHolder = "@string/"+setBarTest+"Phone";
        int textInt3 = getResources().getIdentifier(barPhoneHolder, null, getPackageName());
        setBarPhone.setText(textInt3);

        viewAll.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent i = (new Intent(Bar.this, Drinks.class));
                startActivity(i);           
            }

        });
        beer.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                setDrinkType = "";
                setDrinkType = "Beer";
                Intent i = (new Intent(Bar.this, Drinks.class));
                startActivity(i); 

            }

        });
        wine.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                setDrinkType = "";
                setDrinkType = "Wine";
                Intent i = (new Intent(Bar.this, Drinks.class));
                startActivity(i);   

            }

        });
        mixedDrinks.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                setDrinkType = "";
                setDrinkType = "Mixed Drink";
                Intent i = (new Intent(Bar.this, Drinks.class));
                startActivity(i); 

            }

        });

        other.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                setDrinkType = "";
                setDrinkType = "Other";
                Intent i = (new Intent(Bar.this, Drinks.class));
                startActivity(i); 

            }

        });
        getTaxi.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent i = (new Intent(Bar.this, Taxi.class));
                startActivity(i);           
            }

        });


    }
}

Drinks.java

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;

public class Drinks extends Activity{
    TextView drinkHolder;
    public static String drinkType = Bar.setDrinkType;
    String drinkTestHolder="";

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_drinks);
        drinkTestHolder = drinkType;
        drinkHolder = (TextView)findViewById(R.id.drinkTest);
        //String barNameHolder = "@string/"+drinkType;
        //int textInt1 = getResources().getIdentifier(barNameHolder, null, getPackageName());
        drinkHolder.setText(drinkTestHolder);
    }
}

Answer 1

请改为使用发送到启动的意图 Activity:

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