Question

我正在尝试使用菜单打开一个活动，这没有任何问题。但是，当我在我打开的活动上放一个片段时，我收到此错误

06-19 16:38:46.253    2732-2732/com.example.broodjepoep.stapvoorstap E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.example.broodjepoep.stapvoorstap, PID: 2732
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.broodjepoep.stapvoorstap/com.example.broodjepoep.stapvoorstap.LayoutFragmentOne}: android.view.InflateException: Binary XML file line #8: Error inflating class fragment
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2212)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2271)
            at android.app.ActivityThread.access$800(ActivityThread.java:144)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1205)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5146)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:732)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:566)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: android.view.InflateException: Binary XML file line #8: Error inflating class fragment
            at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:713)
            at android.view.LayoutInflater.rInflate(LayoutInflater.java:755)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:397)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:353)
            at android.support.v7.app.ActionBarActivityDelegateBase.setContentView(ActionBarActivityDelegateBase.java:228)
            at android.support.v7.app.ActionBarActivity.setContentView(ActionBarActivity.java:102)
            at com.example.broodjepoep.stapvoorstap.LayoutFragmentOne.onCreate(LayoutFragmentOne.java:15)
            at android.app.Activity.performCreate(Activity.java:5231)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2169)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2271)
            at android.app.ActivityThread.access$800(ActivityThread.java:144)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1205)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5146)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:732)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:566)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.ClassCastException: you need to implement senddata method
            at com.example.broodjepoep.stapvoorstap.FirstFragment.onAttach(FirstFragment.java:56)
            at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:849)
            at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1040)
            at android.app.FragmentManagerImpl.addFragment(FragmentManager.java:1142)
            at android.app.Activity.onCreateView(Activity.java:4786)
            at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:689)
            at android.view.LayoutInflater.rInflate(LayoutInflater.java:755)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:397)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:353)
            at android.support.v7.app.ActionBarActivityDelegateBase.setContentView(ActionBarActivityDelegateBase.java:228)
            at android.support.v7.app.ActionBarActivity.setContentView(ActionBarActivity.java:102)
            at com.example.broodjepoep.stapvoorstap.LayoutFragmentOne.onCreate(LayoutFragmentOne.java:15)
            at android.app.Activity.performCreate(Activity.java:5231)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2169)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2271)
            at android.app.ActivityThread.access$800(ActivityThread.java:144)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1205)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5146)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:732)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:566)
            at dalvik.system.NativeStart.main(Native Method)

fwef

菜单项后面的

代码点击

 @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;
        }


        Intent iOne = new Intent(this,LayoutFragmentOne.class);
        Intent iTwo = new Intent(this,LayoutFragmentTwo.class);

        switch(id)
        {
            case R.id.fragOne:
                startActivity(iOne);
                return true;
            case R.id.fragTwo:
                startActivity(iTwo);
                return true;
        }
        return super.onOptionsItemSelected(item);
    }

LayoutFragmentOne.class

package com.example.broodjepoep.stapvoorstap;

import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;

/**
 * Created by Pizza on 19-6-2015.
 */
public class LayoutFragmentOne extends ActionBarActivity
{
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.layout_fragment_one);
    }
}

LayoutFragmentTwo.class

package com.example.broodjepoep.stapvoorstap;

import android.os.Bundle;
import android.os.PersistableBundle;
import android.support.v7.app.ActionBarActivity;

/**
 * Created by Pizza on 19-6-2015.
 */
public class LayoutFragmentTwo extends ActionBarActivity
{
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.layout_fragment_two);
    }
}

如果我在MainActivity上放置两个片段，则没有错误，我可以毫无问题地在它们之间进行通信。只有当我尝试启动活动时才会出现此问题上面有一个片段

这是一个已知的问题，还是有一个已知的修复？

我不知道是否需要它，但这里是Fragment one和Fragment two背后的代码

一：

package com.example.broodjepoep.stapvoorstap;

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

/**
 * Created by Pizza on 19-6-2015.
 */
public class FirstFragment extends Fragment
{
    SendMessage sm;
    Button btnSendData;
    EditText tb1;
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState)
    {
        View v;
        v = inflater.inflate(R.layout.fragment_one,container,false);
        btnSendData = (Button)v.findViewById(R.id.btnSendData);
        tb1 = (EditText)v.findViewById(R.id.tb1);
        btnSendData.setOnClickListener(new Button.OnClickListener()
        {
            @Override
            public void onClick(View v)
            {
                String message;
                message = tb1.getText().toString();
                sm.sendData(message);
            }
        });
        return v;

    }



    interface SendMessage
    {
        public void sendData(String message);
    }

    @Override
    public void onAttach(Activity activity)
    {
        super.onAttach(activity);
        try
        {
            sm = (SendMessage) activity;
        }
        catch (ClassCastException e)
        {
            throw  new ClassCastException("you need to implement senddata method");
        }
    }
}

二：

package com.example.broodjepoep.stapvoorstap;

import android.app.Fragment;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

/**
 * Created by Pizza on 14-6-2015.
 */
public class SecondFragment extends Fragment
{
    TextView txt;
    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
    {
        View v;
        v = inflater.inflate(R.layout.fragment_two,container,false);
        txt = (TextView)v.findViewById(R.id.txt);
        return v;
    }
    public void getData(String message)
    {
        txt.setText(message);
    }

}

Answer 1

错误很明显：

 Caused by: java.lang.ClassCastException: you need to implement senddata method

将片段附加到未实现所述接口的活动时会发生这种情况。它全部写在这段代码中：

@Override
public void onAttach(Activity activity)
{
    super.onAttach(activity);
    try
    {
        sm = (SendMessage) activity;
    }
    catch (ClassCastException e)
    {
        throw  new ClassCastException("you need to implement senddata method");
    }
}

想要使用具有此类代码的片段的活动应该实现接口：

public class LayoutFragmentOne extends ActionBarActivity implements SendMessage
{
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.layout_fragment_one);
    }

    @Override
    public void sendData(String message) {

    }
}

打开一个带有片段的活动？

1 个答案: