可能是重复问题:
如何保存Android应用程序的状态?
我是Java和Android的新手,正在构建一些小项目来学习。我制作了一个金钱跟踪应用程序,允许用户输入值并简单地继续减去它。一切都运行良好,但我希望在关闭和重新打开应用程序时保存或缓存价值。 通过阅读,我发现也许OnPause会起到作用,但还没有完全理解它。
有人能推荐如何做到这一点以及如何将其应用到我的代码中吗?
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());
}
}
});
}
}