Question

我正在练习使用Java/XML的Android编程。

至于下面的代码：我遇到问题的方法是OBClicked。

OBClicked是我在ShareFragment中定义的接口的方法（包含一个复选框和一个启动TextFragment的按钮）。

我这样做了，因为根据我所学到的，在片段中定义接口并覆盖托管活动中的接口是一种很好的方法，可以将该信息传输到另一个片段。

在这种情况下，我覆盖MainActivity中的OBClicked方法，告诉TextFragment（它只是一个TextView）是否选中了ShareFragment中的CheckBox。根据是否已选中，我尝试使用setText告诉TextFragment显示某些文本，但这会导致程序崩溃。这是代码，任何帮助将不胜感激。：

MainActivity：

public class MainActivity extends FragmentActivity implements ShareFragment.ClickListener{

    @Override
    public void oBClicked(boolean x){
        FragmentManager fm = getSupportFragmentManager();
        FragmentTransaction ft = fm.beginTransaction();

        TextView t = (TextView)findViewById(R.id.text_view);
        if(x == true){
            t.setText("The box is checked");
        }else{
            t.setText("The box isn't checked");
        }
        Fragment fragment = new TextFragment();
        ft.replace(R.id.fragmentContainer, fragment);
        ft.addToBackStack(null);
        ft.commit();


    }

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

        FragmentManager fm = getSupportFragmentManager();
        Fragment fragment = fm.findFragmentById(R.id.fragmentContainer);
        if(fragment == null){
            fragment = new ShareFragment();
        }
        FragmentTransaction ft = fm.beginTransaction();
        ft.add(R.id.fragmentContainer, fragment);
        ft.commit();
    }

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

}

ShareFragment：

    public class ShareFragment extends Fragment {
        Button mButton; 
    String mText;
    Boolean mTruthValue;
    CheckBox mCheckBox;
    private int mCounter;
    //CROSS FRAGMENT COMMUNICATION START
    ClickListener mListener;
    public interface ClickListener{
        public void oBClicked(boolean x);
    }

    public void oBClicked(boolean x){
        mListener.oBClicked(x);
    }
    //CROSS FRAGMENT COMMUNICATION FIN

    @Override
    public void onAttach(Activity activity){
        super.onAttach(activity);
        try{
            mListener = (ClickListener) activity;
        }
        catch(Exception e){
            //
        }

    }
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle save){
        View v = inflater.inflate(R.layout.fragment_share, container, false);
        mButton = (Button)v.findViewById(R.id.button1);
        mCheckBox = (CheckBox)v.findViewById(R.id.check_box);
        mCounter = 1;
        mCheckBox.setOnClickListener(new OnClickListener(){
            @Override
            public void onClick(View v){
                mCounter++;
            }
        });
        mButton.setOnClickListener(new OnClickListener(){
            @Override
            public void onClick(View v){
                //mCheckBox = (CheckBox)v.findViewById(R.id.check_box);
                if(mCounter%2 == 0){
                    mTruthValue = true;
                }else{
                    mTruthValue = false;
                }
                oBClicked(mTruthValue);
            }
        });
        return v;
    }

}

TextFragment：

   public class TextFragment extends Fragment{
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle save){
        View v = inflater.inflate(R.layout.fragment_text, container, false);
        return v;
    }
}

Answer 1

   TextView t = (TextView)findViewById(R.id.text_view);
    if(x == true){
        t.setText("The box is checked");
    }else{
        t.setText("The box isn't checked");
    }

这会在您的活动中查找TextView。如果要在TextFragment中获取TextView，则必须在片段的onCreateView或onViewCreated中找到它。要在创建时将数据传递给片段，请使用setArguments和getArguments。

@Override
public void oBClicked(boolean x){
    FragmentManager fm = getSupportFragmentManager();
    FragmentTransaction ft = fm.beginTransaction();
    Fragment fragment = new TextFragment();

    Bundle arguments = new Bundle();
    arguments.putBoolean("data",x);
    fragment.setArguments(arguments);

    ft.replace(R.id.fragmentContainer, fragment);
    ft.addToBackStack(null);
    ft.commit();
}

并在TextFragment的onCreateView中......

public class TextFragment extends Fragment{
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle save){
    View v = inflater.inflate(R.layout.fragment_text, container, false);
    TextView t = (TextView)v.findViewById(R.id.text_view);

     Bundle arguments = getArguments();
     boolean x = arguments.getBoolean("data");

     if(x == true){
       t.setText("The box is checked");
     }else{
       t.setText("The box isn't checked");
     }   
     return v;
}

当我使用setText方法时，我的Android程序崩溃了

1 个答案: