Question

我回到Android应用程序后尝试检索已保存的信息。我没有收到任何错误，但没有任何东西像应该的那样回到应用程序中。有关如何改进我的代码的任何建议吗？

package edu.rasmussen.mobile;

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.Reader;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends Activity {

private final static String STORELOCATION="storelocation.txt";

private EditText txtEditor;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    txtEditor=(EditText)findViewById(R.id.LatDegrees);
    txtEditor=(EditText)findViewById(R.id.LatMinutes);
    txtEditor=(EditText)findViewById(R.id.LatSeconds);
    txtEditor=(EditText)findViewById(R.id.LongDegrees);
    txtEditor=(EditText)findViewById(R.id.LongMinutes);
    txtEditor=(EditText)findViewById(R.id.LongSeconds);
}



public void saveClicked(View v){
    try {
        OutputStreamWriter out=
            new OutputStreamWriter(openFileOutput(STORELOCATION, 0));
        out.write(txtEditor.getText().toString());
        out.close();

        Toast.makeText(this,  "The contents are saved in the File.",         Toast.LENGTH_LONG).show();
    }

    catch (Throwable t)
    {
        Toast.makeText(this, "Exception: "+t.toString(),     Toast.LENGTH_LONG).show();

    }
}

public void readFileInEditor()
{
    try
    {
        InputStream in = openFileInput(STORELOCATION);

        if (in != null)
        {
            Reader tmp = null;
            BufferedReader reader=new BufferedReader(tmp);
            String str;
            StringBuilder buf=new StringBuilder();
            while ((str = reader.readLine()) !=null)
            {
                buf.append(str+"n");
            }
        in.close();
        txtEditor.setText(buf.toString());
        }
    }

catch (java.io.FileNotFoundException e)
{

}

    catch (Throwable t)
    {
        Toast.makeText(this, "Exception: "+t.toString(), Toast.LENGTH_LONG)
        .show();
    }
}

public void retrievedClicked(View v){
    try {
        FileInputStream fIn = openFileInput("storelocation");
        InputStreamReader isr = new InputStreamReader(fIn);


        Toast.makeText(this,  "The contents have been retreived.", Toast.LENGTH_LONG).show();
    }

    catch (IOException ioe)

    {
        ioe.printStackTrace();

    }
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

}

＆GT;

Answer 1

您的EditText变量'txtEditor'只能引用一个EditText视图。通过在onCreate（）中将其分配给另一个视图，它不会指向所有这些视图，而只指向最后一个视图。所以它指向LongSeconds，这是你做的最后一个任务：

txtEditor=(EditText)findViewById(R.id.LongSeconds);

假设您的保存和检索代码有效，因此您只保存并检索LongSeconds的值。要保存所有视图的状态，每个视图都需要一个不同的变量来引用它们，例如：

txtEditorLatD = (EditText)findViewById(R.id.LatDegrees);
txtEditorLatM = (EditText)findViewById(R.id.LatMinutes);
txtEditorLatS = (EditText)findViewById(R.id.LatSeconds);
txtEditorLongD = (EditText)findViewById(R.id.LongDegrees);
txtEditorLongM = (EditText)findViewById(R.id.LongMinutes);
txtEditorLongS = (EditText)findViewById(R.id.LongSeconds);

保存时，您需要依次使用某种分隔符来写出每个值的值。然后，当您重新读取数据时，请通过分隔符将其拆分并重新填充视图。

更简单的保存/恢复方法是使用SharedPreferences，这是一种常用的方法来存储活动的状态（或您希望保留的任何其他数据）。 SharedPreferences文件包含键/值对。例如，保存每个EditText的字符串值：

SharedPreferences.Editor editor = getPreferences(Activity.MODE_PRIVATE).edit();
editor.putString("LatDegrees", txtEditorLatD.getText().toString());
editor.putString("LatMinutes", txtEditorLatM.getText().toString());
//repeat for each view to be stored
editor.apply();

要检索该数据：

SharedPreferences sp = getPreferences(Activity.MODE_PRIVATE);
txtEditorLatD.setText(sp.getString("LatDegrees", ""));
txtEditorLatM.setText(sp.getString("LatMinutes", ""));
//repeat for each view to be restored

当我重新打开我的应用程序时，从保存的本地文件中检索已保存的信息

1 个答案: