getFloatExtra() 总是返回默认值

Question

我是 Android 开发新手。我正在尝试将评级信息从一项活动传递到另一项活动。但是第二个活动似乎没有收到我通过 getFloatExtra 传递的值，而是采用了默认值。请帮我找出我做错了什么。

这是我的第一个活动：

public class FirstActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_first);
    }

    public void enter(View view) {
        RatingBar vRatingBar = (RatingBar) findViewById(R.id.ratingBar);
        float rate = vRatingBar.getRating();

        Intent goToSecond = new Intent();
        goToSecond.setClass(getApplicationContext(),SecondActivity.class);
        goToSecond.putExtra("stars",rate);
        startActivity(goToSecond);
    }
}

这是我的第二个活动：

public class SecondActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);
        Intent caller = new Intent();
        Float rating = caller.getFloatExtra("stars",0.0f);
        TextView vTextView = (TextView) findViewById(R.id.textViewSecondActivity);
        vTextView.setText("Welcome to The Second Activity. Your Rating:" + rating);
    }
}

并且输出作为图像附加 The First Activity, clicking the button will take to The Second Activity

The Second Activity

Answer 1

在第二个活动中，您正在创建一个new Intent()

替换：

Intent caller = new Intent();

通过

Intent caller = getIntent();

    Bundle bundle = caller.getExtras();
    if(bundle!=null){
    float rating= bundle.getFloat("stars",0.0f);
    //continue...
   TextView vTextView = (TextView) findViewById(R.id.textViewSecondActivity);
        vTextView.setText("Welcome to The Second Activity. Your Rating:" + rating);
    }