小编Caz*_*azs的帖子

我需要在不清空 php 代码的情况下写入文件中的特定行。

$file="variables.php";
$linecount = 0;
$handle = fopen($file, "r");
while(!feof($handle)){
  $line = fgets($handle);
  $linecount++;
}

$linecount=$linecount-1;
echo $linecount;

fclose($handle);


$handle = fopen($file, "a+");
fwrite($handle, "$newvar=null". "\n");

花时间试图从android调用一个json,但问题是上下文的混乱,这是错误返回我

    02-09 19:48:05.494 16350-16350/com.example.cesar.mybankaccess E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.cesar.mybankaccess, PID: 16350
java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.Context android.content.Context.getApplicationContext()' on a null object reference
at restful.dao.PatronSingleton.getRequestQueue(PatronSingleton.java:37)
at restful.dao.PatronSingleton.<init>(PatronSingleton.java:25)
at restful.dao.PatronSingleton.getInstance(PatronSingleton.java:30)
at restful.dao.Cliente.dologin(Cliente.java:84)
at restful.RestfulOperacional.dologin(RestfulOperacional.java:22)
at com.example.cesar.mybankaccess.view.Login.dologin(Login.java:118)
at com.example.cesar.mybankaccess.view.Login.access$100(Login.java:30)
at com.example.cesar.mybankaccess.view.Login$2.onClick(Login.java:67)
at android.view.View.performClick(View.java:5198)
at android.view.View$PerformClick.run(View.java:21147)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

我没有得到修复,我确定是上下文getContext或类似的,但无法构建一个

public class RestfulOperacional {
    Cliente cliente;

    public RestfulOperacional() {
        cliente = new Cliente();
    }

    public Object dologin(String s, String …

有这个代码我只需要显示一个吐司,如果点击接受或取消,但不能理解为什么是错的如何解决？错误是在toast上getapplicationcontext() 我学习关于android的对话和吐司

    import android.app.AlertDialog;
    import android.app.Dialog;
    import android.content.DialogInterface;
    import android.os.Bundle;
    import android.support.v4.app.DialogFragment;
    import android.util.Log;
    import android.widget.Toast;

    public class confirmacion extends DialogFragment {
    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState){
        AlertDialog.Builder builder= new AlertDialog.Builder(getActivity());
        builder.setMessage("Confirmar?").setTitle("confirmacion")
        .setPositiveButton("aceptar", new DialogInterface.OnClickListener() {

            @Override
            public void onClick(DialogInterface dialog, int which) {
    Log.i("dialogos","aceptado");
    dialog.cancel();
    Toast.makeText(getApplicationContext(), "Eliminacion fallida.", Toast.LENGTH_LONG).show();

            }


        }).setNegativeButton("cancelar", new DialogInterface.OnClickListener() {

            @Override
            public void onClick(DialogInterface dialog, int which) {
    Log.i("dialogos","cancelada");
    dialog.cancel();
            }
        });

        return builder.create();

    }

    }