当用户滑动时将 EditText.getText 从 FirstFragment 传递到 SecondFragment

Question

我想做什么：
在 FirstFragment 中，用户可以输入他的体重。
在 SecondFragment 中，重量应显示在 TextView
中该值应在用户滑动时传递。

我尝试了大约 3 个操作方法并阅读了很多关于片段的内容，但我仍然找不到合适的解决方案。由于我对片段有点陌生，也可能是我采用了一种不常见的方式来生成片段，因此它不起作用，但我还想不出来。

正如您所见，实际上代码中存在错误，因为我试图通过 MainActivity

访问 FirstFragment 的方法

为了简单起见，我没有发布两个片段 xlm 的完整代码。
first_frag.xml 有一个 EditText（id：getWeight）框，您只能在其中输入最多 3 位数字
second_frag.xml 有一个 TextView（id：txtAlcLvl）

activity_main.xml:

<android.support.v4.view.ViewPager
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/viewPager"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
/>

MainActivity.java:

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentStatePagerAdapter;
import android.support.v4.view.ViewPager;


public class MainActivity extends FragmentActivity {

    Calculator calc = new Calculator();
    ViewPager pager;
    private MyPagerAdapter myPagerAdapter;
    String TabFragmentB;



    public void setTabFragmentB(String t){
        TabFragmentB = t;
    }

    public String getTabFragmentB(){
        return TabFragmentB;
    }

    public Calculator getCalc(){
        return this.calc;
    }

    public void getWeight(){
        FragmentManager fm = getSupportFragmentManager();
        FirstFragment fragment = (FirstFragment)fm.findFragmentById(R.id.i_dont_know_the_id);
        //failure because trying to get access to Method of FirstFragment
        fragment.getWeight();
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);


        final MyPagerAdapter pagerAdapter = new MyPagerAdapter(getSupportFragmentManager());
        pager = (ViewPager) findViewById(R.id.viewPager);
        pager.setAdapter(pagerAdapter);


        pager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(final int i, final float v, final int i2) {
            }

            @Override
            public void onPageSelected(final int i) {
                YourFragmentInterface fragment = (YourFragmentInterface) pagerAdapter.instantiateItem(pager, i);
                if (fragment != null) {
                    fragment.fragmentBecameVisible();
                }
            }



            @Override
            public void onPageScrollStateChanged(final int i) {
            }
        });

    }


    public interface YourFragmentInterface {
        void fragmentBecameVisible();
    }

    private class MyPagerAdapter extends FragmentStatePagerAdapter {

        public MyPagerAdapter(FragmentManager fm) {
            super(fm);
        }

        @Override
        public Fragment getItem(int position) {
            switch(position) {

                case 1: return new SecondFragment(); //SecondFragment.newInstance("SecondFragment, Instance 1");

                case 0: return new FirstFragment();

                default: return new FirstFragment(); //FirstFragment.newInstance("FirstFragment, Default");
            }
        }




        @Override
        public int getCount() {
            return 2;
        }
    }
}

FirstFragment.java:

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;

public class FirstFragment extends Fragment implements MainActivity.YourFragmentInterface {

    Button btnBeer;
    Button btnBeerSmall;
    Button btnWine;
    Button btnLiq;
    Button btnSch;
    Button btnWater;
    Button btnMale;
    Button btnFemale;
    Calculator calc;
    EditText getWeight;

    public String getWeight(){
        return getWeight.getText().toString();
    }

    @Override
    public void fragmentBecameVisible() {



        // You can do your animation here because we are visible! (make sure onViewCreated has been called too and the Layout has been laid. Source for another question but you get the idea.
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.first_frag, container, false);
        calc = ((MainActivity) getActivity()).getCalc();

        btnBeer = (Button) v.findViewById(R.id.btnBeer);
        btnBeerSmall = (Button) v.findViewById(R.id.btnBeerSmall);
        btnWine = (Button) v.findViewById(R.id.btnWine);
        btnLiq = (Button) v.findViewById(R.id.btnLiq);
        btnSch = (Button) v.findViewById(R.id.btnSch);
        btnWater = (Button) v.findViewById((R.id.btnWater));
        btnMale = (Button) v.findViewById(R.id.btnMale);
        btnFemale = (Button) v.findViewById(R.id.btnFemale);
        getWeight = (EditText) v.findViewById(R.id.getWeight);

        btnBeer.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                calc.addConsumption(0);
            }
        });

        btnBeerSmall.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                calc.addConsumption(1);
            }
        });

        btnWine.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                calc.addConsumption(2);
            }
        });

        btnLiq.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                calc.addConsumption(3);
            }
        });

        btnSch.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                calc.addConsumption(4);
            }
        });

        btnWater.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                calc.addConsumption(5);
            }
        });

        btnMale.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                btnMale.setBackgroundResource(R.drawable.male_false);
                btnFemale.setBackgroundResource(R.drawable.female);
            }
        });

        btnFemale.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                btnFemale.setBackgroundResource(R.drawable.female_false);
                btnMale.setBackgroundResource(R.drawable.male);
            }
        });


        return v;

    }

    public static FirstFragment newInstance(String text) {

        FirstFragment f = new FirstFragment();
        Bundle b = new Bundle();
        b.putString("msg", text);


        f.setArguments(b);

        return f;
    }
}

SecondFragment.java:

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageButton;
import android.widget.TextView;



public class SecondFragment extends Fragment implements MainActivity.YourFragmentInterface {


    TextView txtAlcLvl;
    TextView txtTimeToZero;
    TextView txtPeak;
    ImageButton btnReset;
    Calculator calc;
    String weight;



    @Override
    public void fragmentBecameVisible() {
        calc.person.setSex(false);
        calc.person.setWeight(80);
        txtAlcLvl.setText(((MainActivity) getActivity()).getWeight());
        //txtAlcLvl.setText(String.format("%.2f", calc.getCurrentLevel()) + "‰");

        // You can do your animation here because we are visible! (make sure onViewCreated has been called too and the Layout has been laid. Source for another question but you get the idea.
    }

    public void setSex(){

    }

    public void setWeight(){
        try{

        }   catch(NumberFormatException e){

        }
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.second_frag, container, false);
        calc = ((MainActivity) getActivity()).getCalc();
        String myTag = getTag();
        ((MainActivity)getActivity()).setTabFragmentB(myTag);

        txtAlcLvl = (TextView) v.findViewById(R.id.txtAlcLvl);
        txtTimeToZero = (TextView) v.findViewById(R.id.txtTimeToZero);
        txtPeak = (TextView) v.findViewById(R.id.txtPeak);
        btnReset = (ImageButton) v.findViewById((R.id.btnReset));

        btnReset.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                calc.resetConsumption();
            }
        });

        return v;
    }

    public void updateText(String t){
        txtAlcLvl.setText(t);
    }

    public static SecondFragment newInstance(String text) {

        SecondFragment f = new SecondFragment();
        Bundle b = new Bundle();
        b.putString("msg", text);

        f.setArguments(b);

        return f;
    }
}

Answer 1

当 activity 调用新片段时，不要尝试 "pass" 您通常期望的值。

相反，请考虑使用一些持久性存储来存储值，例如 SharedPreferences 或 Sqlite 数据库。每个片段都可以根据需要从那里读取和写入值。

Answer 2

你可以反过来做。不要尝试从片段中获取 activity 中的权重，而是尝试从片段中设置 activity 中的权重。

public class MainActivity extends FragmentActivity {
  ...
  private float weight;

  public void setWeight(float weight) {
    this.weight = weight;
  }

  public float getWeight() {
    return this.weight();
  }

然后在你的 FirstFragment 中：

((MainActivity)getActivity()).setWeight(...);

最后在您的 SecondFragment 中：

float weight = ((MainActivity)getActivity()).getWeight();

当用户滑动时将 EditText.getText 从 FirstFragment 传递到 SecondFragment

Pass the EditText.getText from FirstFragment to SecondFragment when the User swipes

java

android

android-fragments

android-viewpager

swipe