Question

我在两个活动之间发送数据时遇到问题 - 我不熟悉编程并认为它与代码的定位有关但我不确定，更可能是它的某些东西简单。

我试图将stepCount中的号码发送到第二个活动，它存储在myText3中并且在第一个活动中可见并且计数正常（它的原始数据但是为现在）。

如果我将值设置为myText3，它会在第二个活动中显示该值，但在stepCount

时它不会显示myText3的值

提前致谢..

第一项活动

import android.content.Intent;
import android.os.CountDownTimer;
import android.support.v7.app.AppCompatActivity;
import android.view.View.OnClickListener;



        import android.hardware.Sensor;
        import android.hardware.SensorEvent;
        import android.hardware.SensorEventListener;
        import android.hardware.SensorManager;
        import android.os.Bundle;
        //import android.support.design.widget.FloatingActionButton;
        //import android.support.design.widget.Snackbar;
        import android.support.v7.app.AppCompatActivity;
        import android.support.v7.widget.Toolbar;
        import android.view.View;
        import android.view.Menu;
        import android.view.MenuItem;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity implements SensorEventListener {
    TextView tvx, tvy, tvz, display, display2, display3;
    float total;
    float stepCount;
    float x, y, z;
    float xPrev,yPrev, zPrev;
    float totalPrev = 0;
    Button saveButton;



    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        //setSupportActionBar(toolbar);

        /*FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });*/



        tvx = (TextView) findViewById(R.id.textView);
        tvy = (TextView) findViewById(R.id.textView2);
        tvz = (TextView) findViewById(R.id.textView3);
        display = (TextView) findViewById(R.id.display);
        display2 = (TextView) findViewById(R.id.display2);
        display3 = (TextView) findViewById(R.id.display3);
        saveButton = (Button) findViewById(R.id.saveButton);

        SensorManager mgr = (SensorManager) getSystemService(SENSOR_SERVICE);
        Sensor GSensor = mgr.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
        mgr.registerListener(this, GSensor, SensorManager.SENSOR_DELAY_NORMAL);



    }

    @Override
    public void onSensorChanged(SensorEvent event) {
        // called byt the system every 10 ms



        x = event.values[0];
        y = event.values[1];
        z = event.values[2];
        total = x + y + z;

        new CountDownTimer(3000, 1000) {
            public void onFinish() {
                // When timer is finished
                // Execute your code here
                xPrev = x;
                yPrev = y;
                zPrev = z;
                totalPrev = xPrev + yPrev + zPrev;
            }

            public void onTick(long millisUntilFinished) {
                // millisUntilFinished    The amount of time until finished.
            }
        }.start();



       if (Math.abs(total - totalPrev) > 20) {
           stepCount++;
       }


        tvx.setText(String.valueOf(event.values[0]));
        tvy.setText(String.valueOf(event.values[1]));
        tvz.setText(String.valueOf(event.values[2]));

        String mytext = Float.toString(total);
        display.setText(mytext);

        String mytext2 = Float.toString(totalPrev);
        display2.setText(mytext2);

        String mytext3 = Float.toString(stepCount);
        display3.setText(mytext3);

        saveButton.setOnClickListener(new View.OnClickListener() {
            String mytext3;
            @Override
            public void onClick(View v) {
                Intent A2Intent = new Intent (v.getContext(), Main2Activity.class);
                //EditText et = (EditText) findViewById(R.id.editText);
                // pass the entered phone number to the next activity
                //A2Intent.putExtra("phoneNumber", tv2.getText());
                //String ph = et.getText().toString();
                A2Intent.putExtra("steps", mytext3);
                // start the next activity/page
                startActivity(A2Intent);
            }
        });








    }

    @Override
    public void onAccuracyChanged(Sensor sensor, int accuracy) {

    }

    /*@Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    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();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }*/
    /*saveButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent A2Intent = new Intent (v.getContext(), Main2Activity.class);
            EditText et = (EditText) findViewById(R.id.editText);
            // pass the entered phone number to the next activity
            //A2Intent.putExtra("phoneNumber", tv2.getText());
            String ph = et.getText().toString();
            A2Intent.putExtra("phoneNumber", ph);
            // start the next activity/page
            startActivity(A2Intent);
        }
    })*/

}

第二项活动

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class Main2Activity extends AppCompatActivity {

    TextView textView1;
    Button newButton;
    String displayCount;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);

        textView1 = (TextView) findViewById(R.id.editText);
        newButton = (Button) findViewById(R.id.button);

        displayCount = getIntent().getStringExtra("steps");
        textView1.setText(displayCount);

    }
}

Answer 1

在saveButton onClickListener中，您正在创建一个新的String mytext3，然后将空的未初始化的字符串传递给您的意图。相反，你可以做的是使用findViewById在textView中检索实际的mytext3，然后将其传入。

Answer 2

将String mytext3 = Float.toString(stepCount);放入saveButton onClick()这样的内容：

saveButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent A2Intent = new Intent (v.getContext(), Main2Activity.class);
            String mytext3 = Float.toString(stepCount);
            A2Intent.putExtra("steps", mytext3);
            startActivity(A2Intent);
        }
    });

Answer 3

    saveButton.setOnClickListener(new View.OnClickListener() {
               // String mytext3;
               //you are giving intent a empty string here  comment above line
                @Override
                public void onClick(View v) {
                    Intent A2Intent = new Intent (v.getContext(), Main2Activity.class);
                    //EditText et = (EditText) findViewById(R.id.editText);
                    // pass the entered phone number to the next activity
                    //A2Intent.putExtra("phoneNumber", tv2.getText());
                    //String ph = et.getText().toString();
                    A2Intent.putExtra("steps", mytext3);
                    // start the next activity/page
                    startActivity(A2Intent);
                }
            });

评论完成后，您必须final String mytext3才能在onClick中访问它。

在Android Studio的两个活动之间发送数据

3 个答案: