在尝试了多种不同的方式来表达以下程序后,我无法将值从一个 Activity 传递到另一个 Activity 。由于某种原因, bundle 似乎一直为空。我不认为这可能是权限问题。
主要 Activity :
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void ButtonRAWclick(View view)
{
Intent intent = new Intent(MainActivity.this
, RestClient.class);
intent.putExtra("type", "RAW_TYPE");
startActivity(intent);
}
public void ButtonHTTPclick(View view)
{
Intent intent = new Intent(MainActivity.this
, RestClient.class);
intent.putExtra("type", "HTTP_TYPE");
startActivity(intent);
}
public void ButtonJSONclick(View view)
{
Intent intent = new Intent(MainActivity.this
, RestClient.class);
intent.putExtra("type", "JSON_TYPE");
startActivity(intent);
}
}
RestClient:
public class RestClient extends AppCompatActivity implements SensorListener {
RawHttpSensor rhs1;
TextSensor rhs2;
TextView temperature;
String output;
String type;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_rest_client);
Bundle bundle = getIntent().getExtras();
if (bundle != null) {
type = bundle.getString("type");
}
if (type == "RAW_TYPE") {
rhs1 = new RawHttpSensor();
temperature = (TextView) findViewById(R.id.temperature);
rhs1.registerListener(this);
rhs1.getTemperature();
}
if (type == "HTTP_TYPE")
{
rhs2 = new TextSensor();
temperature = (TextView) findViewById(R.id.temperature);
rhs2.registerListener(this);
rhs2.getTemperature();
}
if (type == "JSON_TYPE")
{
...
}
...
}
有人可以帮我发现这个错误吗?
最佳答案
不要
if(type ==
做
if(type.equals("YOUR_STRING"))
您应该使用equals()
Compares this string to the specified object. The result is true if and only if the argument is not null and is a String object that represents the same sequence of characters as this object.
if (type.equals("RAW_TYPE")) {
rhs1 = new RawHttpSensor();
temperature = (TextView) findViewById(R.id.temperature);
rhs1.registerListener(this);
rhs1.getTemperature();
}
关于java - 无法从始终为空的包中获取值,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/46876018/