[英]Unable to read/write to file in android
我正在尝试让我的应用程序将文本写入EditText的文本文件,并从中读取到TextView。 它从未更新过TextView,现在应用程序崩溃了。 任何建议将非常感谢!
public class MainActivity extends Activity implements OnClickListener {
String file = Environment.getExternalStorageDirectory() + "/CSCI598.txt";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button rea = (Button) findViewById(R.id.reads1);
rea.setOnClickListener(this);
Button ap = (Button) findViewById(R.id.appends1);
ap.setOnClickListener(this);
}
private void toast(String text)
{
Context context = getApplicationContext();
Toast toast = Toast.makeText(context, text, Toast.LENGTH_LONG);
toast.show();
}
@SuppressWarnings("resource")
@Override
public void onClick(View v) {
TextView tv=(TextView)findViewById(R.id.textView1);
EditText et=(EditText)findViewById(R.id.editText1);
switch(v.getId()) {
case R.id.reads1:
try
{
FileInputStream fis = new FileInputStream(file);
BufferedReader bfr = new BufferedReader(new InputStreamReader(fis));
String in;
StringBuffer stringBuffer = new StringBuffer();
while ((in = bfr.readLine()) != null) {
stringBuffer.append(in + "\n");
}
tv.setText(stringBuffer.toString());
toast("File successfully loaded.");
}
catch (Exception ex)
{
toast("Error loading file: " + ex.getLocalizedMessage());
}
break;
case R.id.appends1:
String txt=et.getText().toString();
try
{
FileWriter writer = new FileWriter(file);
writer.write(txt);
writer.flush();
writer.close();
toast("File successfully saved.");
}
catch (Exception ex)
{
toast("Error saving file: " + ex.getLocalizedMessage());
}
break;
}
}
}
使用Environment.getExternalStorageDirectory()
获取sdcard目录。 尝试在代码中更改此行:
String file = "sdcard/CSCI598.txt";
附:
String file = Environment.getExternalStorageDirectory() + "/CSCI598.txt";
此外,正如@Yahya提到的那样,请确保您在Android清单文件中拥有此权限:
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
如果这不起作用。 尝试阅读这样的文件:
FileReader fr = new FileReader(file);
BufferedReader inputReader = new BufferedReader(fr);
然后就像现在一样使用while循环。
像这样写文件
FileWriter out = new FileWriter(file, true);
out.write(txt + "\n");
out.close();
提供崩溃日志。
<
uses-permission android:name =“android.permission.WRITE_EXTERNAL_STORAGE”><
/ uses-permission>
而不是像String file =“sdcard / CSCI598.txt”那样使用硬编码路径; 使用下面
String file = Environment.getExternalStorageDirectory()+“/ CSCI598.txt”;
当您使用模拟器时,您在创建AVD时有很多SD卡空间
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