java - 无法从始终为空的包中获取值

Question

这个问题已经有答案了:

How do I compare strings in Java? (23 个回答)

已关闭 5 年前。

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？

Answer 1

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();
    }