从alertDialog构建器获取editText值

我是新来的android。我需要得到editText's搜索某些东西的价值。但是当我运行程序时，出现错误null pointer exception.

“EditText etSearch”没有获取它的文本。

请帮我。 谢谢。

public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_search) {
            AlertDialog.Builder builder = new AlertDialog.Builder(
                    MainActivity.this);
            // Get the layout inflater
            LayoutInflater inflater = MainActivity.this.getLayoutInflater();

            // Inflate and set the layout for the dialog
            // Pass null as the parent view because its going in the dialog
            // layout
            builder.setView(inflater.inflate(R.layout.dialog_save, null))

                    // Add action buttons
                    .setPositiveButton("Search",
                            new DialogInterface.OnClickListener() {
                                @Override
                                public void onClick(DialogInterface dialog,
                                        int id) {
                                    final EditText etSearch = (EditText) findViewById(R.id.etSearchText);
                                    mSearchText = etSearch.getText().toString();

                                }
                            })
                    .setNegativeButton("Cancel",
                            new DialogInterface.OnClickListener() {
                                public void onClick(DialogInterface dialog,
                                        int id) {
                                    dialog.cancel();
                                }
                            });
            // return builder.create();
            AlertDialog alertDialog = builder.create();
            alertDialog.show();
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

当您必须提供对话框视图的引用时，要从对话框中查找视图。

 LayoutInflater inflater = MainActivity.this.getLayoutInflater();
            View mView = inflater.inflate(R.layout.dialog_save, null);
            final EditText etSearch = (EditText)mView.findViewById(R.id.etSearchText);
            builder.setView(mView)

完整代码：

public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_search) {
            AlertDialog.Builder builder = new AlertDialog.Builder(
                    MainActivity.this);
            // Get the layout inflater
            LayoutInflater inflater = MainActivity.this.getLayoutInflater();
            View mView = inflater.inflate(R.layout.dialog_save, null);
            final EditText etSearch = (EditText)mView.findViewById(R.id.etSearchText);
            builder.setView(mView)

                    // Add action buttons
                    .setPositiveButton("Search",
                            new DialogInterface.OnClickListener() {
                                @Override
                                public void onClick(DialogInterface dialog,
                                        int id) {

                                    mSearchText = etSearch.getText().toString();

                                }
                            })
                    .setNegativeButton("Cancel",
                            new DialogInterface.OnClickListener() {
                                public void onClick(DialogInterface dialog,
                                        int id) {
                                    dialog.cancel();
                                }
                            });
            // return builder.create();
            AlertDialog alertDialog = builder.create();
            alertDialog.show();
            return true;
        }
        return super.onOptionsItemSelected(item);
    }