Android：关闭应用程序时保存实例状态[重复]

Question

可能重复：
How do I save an Android application's state?

我是 Java 和 Android 的新手，正在构建一些小项目来学习。我制作了一个资金跟踪应用程序，它允许用户输入值并且它只是继续减去它。一切正常，但我希望在应用程序关闭并重新打开时保存或缓存这些值。 阅读时，我发现也许 OnPause 可以解决问题，但仍然不是 100% 理解它。

谁能推荐如何做到这一点以及如何应用于我的代码？

非常感谢您的帮助！！

package ps.age.sl;


import java.text.NumberFormat;
import java.util.Locale;


import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.TextView;


public class MoneyTrackerActivity extends Activity {
    /** Called when the activity is first created. */
        ImageButton subtract;


        EditText startingmoney,submoney, endmoney, tracker;
        Locale currentLocale = Locale.getDefault();





    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

     //   startingmoney = (EditText) findViewById (R.id.firstmoney);
      //  submoney = (EditText) findViewById (R.id.submoney);
       // subtract = (ImageButton) findViewById (R.id.subbutton);
       // endmoney = (EditText) findViewById (R.id.endtv);
       // tracker = (EditText) findViewById (R.id.trackertv);

        startingmoney.setText("");
        submoney.setText("");
        endmoney.setText("");

subtract.setOnClickListener(new View.OnClickListener() {
         double currentValue=0;       
         double startValue=0;       
            public void onClick(View v) throws  NumberFormatException {


                    if (v == subtract)
                {
                NumberFormat currencyFormatter;
                currencyFormatter = NumberFormat.getCurrencyInstance(currentLocale);



                    String totalString;
                    String x = startingmoney.getText().toString();
                    String y = submoney.getText().toString ();
                            double total;
                        double xm = 0.00;
                        double ym =0.00;

                         try
                          {
                              xm = Double.parseDouble(x);
                          }
                         catch(NumberFormatException n)
                          {
                              xm = 0.00;
                          }
                         try
                         {
                                 ym = Double.parseDouble(y);
                         }
                        catch(NumberFormatException n)
                         {
                                ym = 0.00;
                         }

                   if(startValue!=xm){
                       startValue=xm;
                       currentValue=xm;
                   }

                   currentValue = currentValue -ym;


                    totalString = currencyFormatter.format(currentValue);
                    endmoney.setText(totalString);

                    tracker.setText("you have entered " + totalString +"\n" + tracker.getText().toString());



              }
                    }
                                        });
    }
                }

Answer 1

请使用SharedPreferences 将数据存储在私有应用程序存储中。在 onPause 方法中实现SharedPrefernces，如下所示：

 @Override
    protected void onPause() 
    {
      super.onPause(); 
      // Store values between instances here
      SharedPreferences preferences = getSharedPreferences("sharedPrefs", 0);
      SharedPreferences.Editor editor = preferences.edit();
      editor.putString("CLASSLABEL", this.getLocalClassName()); // value to store
      editor.putString("STRINGLABEL",String1 );
      editor.putString("STRINGLABEL1",String2);
      // Commit to storage
      editor.commit();
    }