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我是Android新手,正在嘗試導航和顯示信息。我成功地在這個應用程序的主視圖上放置了一個微調器,但是當我點擊另一個視圖(通過執行goFilter的Butoton)並返回(通過執行goHome的按鈕)時,會出現佔位符。我確定它與goHome沒有加載微調器類信息有關,但我不知道如何以不同的方式做。當我從另一個主視圖返回時,不會顯示Android微調框
對此提出建議? .java代碼如下:
package com.example.hellorelative;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.AdapterView;
public class HelloRelative extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Spinner spinner = (Spinner) findViewById(R.id.spinner);
ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(
this, R.array.planets_array, android.R.layout.simple_spinner_item);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner.setAdapter(adapter);
spinner.setOnItemSelectedListener(new MyOnItemSelectedListener());
}
public class MyOnItemSelectedListener implements OnItemSelectedListener {
public void onItemSelected(AdapterView<?> parent,
View view, int pos, long id) {
Toast.makeText(parent.getContext(), "The planet is " +
parent.getItemAtPosition(pos).toString(), Toast.LENGTH_LONG).show();
}
public void onNothingSelected(AdapterView parent) {
// Do nothing.
}
}
public void goFilter(View view) {
setContentView(R.layout.c_filter);
}
public void goHome(View view) {
setContentView(R.layout.main);
}
}
不相關,但最好將內部類聲明爲static(也可能是private) - 「private static class MyOnItemSelectedListener ...」 – MByD