Java 单击按钮即可新建RecyclerView项

我对Android有点陌生，所以请原谅我的缺点

我在

activity\u main.xml

中有一个floatingAction按钮，每当单击它时，我都希望它带我到一个新的活动，其中有两个EditText字段，还有另一个FAB。
我想做的是，每当输入文本并按下

活动中的FAB\u new\u goal.xml

时，它应该使用

@+id/edit\u goalTitle

文本中的文本创建一个RecyclerView。
它显示了

返回数据中不兼容类型的错误和显示无法解析
MainActivity.java中的方法
getData（）

这是我的密码：

MainActivity.java
：

public class MainActivity extends AppCompatActivity {

private Toolbar toolbar;
private RVAdapter adapter;
private RecyclerView recyclerView;
private EditText editGoalTitle;
private String stringGoalTitle;

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

    toolbar = (Toolbar) findViewById(R.id.app_bar);
    setSupportActionBar(toolbar);

    getSupportActionBar().setDisplayShowHomeEnabled(true);
    NavigationDrawerFragment drawerFragment = (NavigationDrawerFragment) getSupportFragmentManager().findFragmentById(R.id.fragment_navigation_drawer);
    drawerFragment.setUp(R.id.fragment_navigation_drawer, (DrawerLayout) findViewById(R.id.drawer_layout), (Toolbar) findViewById(R.id.app_bar));

    recyclerView = (RecyclerView) findViewById(R.id.goalList);
    recyclerView.setHasFixedSize(true);
    adapter = new RVAdapter(getApplicationContext(), getData());
    recyclerView.setAdapter(adapter);
    recyclerView.setLayoutManager(new LinearLayoutManager(getApplicationContext()));



}

public RVData mSetRecyclerGoalTitle(View view) {

    editGoalTitle = (EditText) findViewById(R.id.edit_goalTitle);
    editGoalTitle.setText(R.string.dummyTxt);
    stringGoalTitle = editGoalTitle.getText().toString();


    public List<RVData> getData () {
        List<RVData> data = new ArrayList<>();
        String[] titles = {};
        if (stringGoalTitle != null) {
            titles = new String[]{stringGoalTitle};
        } else {
            titles = new String[]{"DummyText1"};
        }
        for (int i = 0; i <= titles.length; i++) {
            RVData current = new RVData();
            current.goalTitle = titles[i];
            data.add(current);
        }
        return data;
    }
}

public void newGoal(View view) {
    Intent intent = new Intent(MainActivity.this, NewGoal.class);
    startActivity(intent);
}

@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);
}
}

import android.widget.CheckBox;

public class RVData {
CheckBox checkBox;
String goalTitle;

}

public class RVAdapter extends RecyclerView.Adapter<RVAdapter.myViewHolder> {

List<RVData> data = Collections.emptyList();
private LayoutInflater inflater;

public RVAdapter(Context context, List<RVData> data) {
    inflater = LayoutInflater.from(context);
    this.data = data;
}

@Override
public myViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
    View view = inflater.inflate(R.layout.goal_row, viewGroup, false);
    myViewHolder holder = new myViewHolder(view);
    return holder;
}

@Override
public void onBindViewHolder(myViewHolder viewHolder, int position) {
    RVData current = data.get(position);
    viewHolder.title.setText(current.goalTitle);

}

@Override
public int getItemCount() {
    return data.size();
}

class myViewHolder extends RecyclerView.ViewHolder {
    //@Bind(R.id.goalRowTitle)
    TextView title;
    //@Bind(R.id.goalRowCB)
    CheckBox checkBox;

    public myViewHolder(View itemView) {
        super(itemView);
        title = (TextView) itemView.findViewById(R.id.goalRowTitle);
        checkBox = (CheckBox) itemView.findViewById(R.id.goalRowCB);
    }
}
}

public class NewGoal extends AppCompatActivity {

private Toolbar toolbar;

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

    toolbar = (Toolbar) findViewById(R.id.app_bar);
    setSupportActionBar(toolbar);

    getSupportActionBar().setHomeButtonEnabled(true);
    getSupportActionBar().setDisplayHomeAsUpEnabled(true);

}

@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_new_goal, 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;
    }

    if(id == android.R.id.home)
    {
        NavUtils.navigateUpFromSameTask(this);
    }
    return super.onOptionsItemSelected(item);
}
}

RVAdapter.java
：

public class MainActivity extends AppCompatActivity {

private Toolbar toolbar;
private RVAdapter adapter;
private RecyclerView recyclerView;
private EditText editGoalTitle;
private String stringGoalTitle;

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

    toolbar = (Toolbar) findViewById(R.id.app_bar);
    setSupportActionBar(toolbar);

    getSupportActionBar().setDisplayShowHomeEnabled(true);
    NavigationDrawerFragment drawerFragment = (NavigationDrawerFragment) getSupportFragmentManager().findFragmentById(R.id.fragment_navigation_drawer);
    drawerFragment.setUp(R.id.fragment_navigation_drawer, (DrawerLayout) findViewById(R.id.drawer_layout), (Toolbar) findViewById(R.id.app_bar));

    recyclerView = (RecyclerView) findViewById(R.id.goalList);
    recyclerView.setHasFixedSize(true);
    adapter = new RVAdapter(getApplicationContext(), getData());
    recyclerView.setAdapter(adapter);
    recyclerView.setLayoutManager(new LinearLayoutManager(getApplicationContext()));



}

public RVData mSetRecyclerGoalTitle(View view) {

    editGoalTitle = (EditText) findViewById(R.id.edit_goalTitle);
    editGoalTitle.setText(R.string.dummyTxt);
    stringGoalTitle = editGoalTitle.getText().toString();


    public List<RVData> getData () {
        List<RVData> data = new ArrayList<>();
        String[] titles = {};
        if (stringGoalTitle != null) {
            titles = new String[]{stringGoalTitle};
        } else {
            titles = new String[]{"DummyText1"};
        }
        for (int i = 0; i <= titles.length; i++) {
            RVData current = new RVData();
            current.goalTitle = titles[i];
            data.add(current);
        }
        return data;
    }
}

public void newGoal(View view) {
    Intent intent = new Intent(MainActivity.this, NewGoal.class);
    startActivity(intent);
}

@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);
}
}

import android.widget.CheckBox;

public class RVData {
CheckBox checkBox;
String goalTitle;

}

public class RVAdapter extends RecyclerView.Adapter<RVAdapter.myViewHolder> {

List<RVData> data = Collections.emptyList();
private LayoutInflater inflater;

public RVAdapter(Context context, List<RVData> data) {
    inflater = LayoutInflater.from(context);
    this.data = data;
}

@Override
public myViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
    View view = inflater.inflate(R.layout.goal_row, viewGroup, false);
    myViewHolder holder = new myViewHolder(view);
    return holder;
}

@Override
public void onBindViewHolder(myViewHolder viewHolder, int position) {
    RVData current = data.get(position);
    viewHolder.title.setText(current.goalTitle);

}

@Override
public int getItemCount() {
    return data.size();
}

class myViewHolder extends RecyclerView.ViewHolder {
    //@Bind(R.id.goalRowTitle)
    TextView title;
    //@Bind(R.id.goalRowCB)
    CheckBox checkBox;

    public myViewHolder(View itemView) {
        super(itemView);
        title = (TextView) itemView.findViewById(R.id.goalRowTitle);
        checkBox = (CheckBox) itemView.findViewById(R.id.goalRowCB);
    }
}
}

public class NewGoal extends AppCompatActivity {

private Toolbar toolbar;

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

    toolbar = (Toolbar) findViewById(R.id.app_bar);
    setSupportActionBar(toolbar);

    getSupportActionBar().setHomeButtonEnabled(true);
    getSupportActionBar().setDisplayHomeAsUpEnabled(true);

}

@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_new_goal, 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;
    }

    if(id == android.R.id.home)
    {
        NavUtils.navigateUpFromSameTask(this);
    }
    return super.onOptionsItemSelected(item);
}
}


activity\u new\u goal.xml
：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
style="@style/DefaultLayoutStyle"
tools:context=".MainActivity">

<include
    android:id="@+id/app_bar"
    layout="@layout/app_bar" />


<android.support.design.widget.FloatingActionButton
    android:id="@+id/fab"
    style="@style/FABStyle"
    android:onClick="newGoal"
    android:src="@drawable/ic_add"
    app:borderWidth="0dp" />

<android.support.v4.widget.DrawerLayout
    android:id="@+id/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_below="@id/app_bar">

    <RelativeLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">

        <android.support.v7.widget.RecyclerView
            android:id="@+id/goalList"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="center"></android.support.v7.widget.RecyclerView>
    </RelativeLayout>

    <fragment
        android:id="@+id/fragment_navigation_drawer"
        android:name="com.kellarapps.zeal.NavigationDrawerFragment"
        android:layout_width="@dimen/nav_drawer_width"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        app:layout="@layout/fragment_navigation_drawer"
        tools:layout="@layout/fragment_navigation_drawer" />

</android.support.v4.widget.DrawerLayout>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
style="@style/DefaultLayoutStyle"
tools:context="com.kellarapps.zeal.NewGoal">

<include
    android:id="@+id/app_bar"
    layout="@layout/app_bar" />

<LinearLayout
    android:id="@+id/goalTitle"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_below="@id/app_bar"
    android:layout_marginTop="10dp"
    android:orientation="horizontal"
    android:paddingEnd="5dp"
    android:paddingLeft="5dp"
    android:paddingRight="5dp"

    android:paddingStart="5dp">

    <TextView
        style="@style/DefaultTVStyle"
        android:text="@string/goal" />

    <EditText
        android:id="@+id/edit_goalTitle"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/goalHint" />
</LinearLayout>

<LinearLayout
    android:id="@+id/goalDescription"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_below="@id/goalTitle"
    android:layout_marginTop="10dp"
    android:orientation="horizontal"
    android:paddingEnd="5dp"
    android:paddingLeft="5dp"
    android:paddingRight="5dp"
    android:paddingStart="5dp">

    <TextView
        style="@style/DefaultTVStyle"
        android:text="@string/goalDescription" />

    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/description"
        android:maxLines="3" />

</LinearLayout>

<android.support.design.widget.FloatingActionButton
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/fab2"
    style="@style/FABStyle"
    android:onClick="mSetRecyclerGoalTitle"
    android:src="@drawable/ic_action_done"
    app:borderWidth="0dp"/>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal"
android:paddingLeft="10dp"
android:paddingStart="10dp">

<CheckBox
    android:id="@+id/goalRowCB"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" />

<TextView
    android:id="@+id/goalRowTitle"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:clickable="true"
    android:gravity="center_horizontal"
    android:text="@string/dummyTxt"
    android:textColor="@color/TextColor"
    android:textSize="17sp" />

goal\u row.xml
：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
style="@style/DefaultLayoutStyle"
tools:context=".MainActivity">

<include
    android:id="@+id/app_bar"
    layout="@layout/app_bar" />


<android.support.design.widget.FloatingActionButton
    android:id="@+id/fab"
    style="@style/FABStyle"
    android:onClick="newGoal"
    android:src="@drawable/ic_add"
    app:borderWidth="0dp" />

<android.support.v4.widget.DrawerLayout
    android:id="@+id/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_below="@id/app_bar">

    <RelativeLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">

        <android.support.v7.widget.RecyclerView
            android:id="@+id/goalList"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="center"></android.support.v7.widget.RecyclerView>
    </RelativeLayout>

    <fragment
        android:id="@+id/fragment_navigation_drawer"
        android:name="com.kellarapps.zeal.NavigationDrawerFragment"
        android:layout_width="@dimen/nav_drawer_width"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        app:layout="@layout/fragment_navigation_drawer"
        tools:layout="@layout/fragment_navigation_drawer" />

</android.support.v4.widget.DrawerLayout>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
style="@style/DefaultLayoutStyle"
tools:context="com.kellarapps.zeal.NewGoal">

<include
    android:id="@+id/app_bar"
    layout="@layout/app_bar" />

<LinearLayout
    android:id="@+id/goalTitle"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_below="@id/app_bar"
    android:layout_marginTop="10dp"
    android:orientation="horizontal"
    android:paddingEnd="5dp"
    android:paddingLeft="5dp"
    android:paddingRight="5dp"

    android:paddingStart="5dp">

    <TextView
        style="@style/DefaultTVStyle"
        android:text="@string/goal" />

    <EditText
        android:id="@+id/edit_goalTitle"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/goalHint" />
</LinearLayout>

<LinearLayout
    android:id="@+id/goalDescription"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_below="@id/goalTitle"
    android:layout_marginTop="10dp"
    android:orientation="horizontal"
    android:paddingEnd="5dp"
    android:paddingLeft="5dp"
    android:paddingRight="5dp"
    android:paddingStart="5dp">

    <TextView
        style="@style/DefaultTVStyle"
        android:text="@string/goalDescription" />

    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/description"
        android:maxLines="3" />

</LinearLayout>

<android.support.design.widget.FloatingActionButton
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/fab2"
    style="@style/FABStyle"
    android:onClick="mSetRecyclerGoalTitle"
    android:src="@drawable/ic_action_done"
    app:borderWidth="0dp"/>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal"
android:paddingLeft="10dp"
android:paddingStart="10dp">

<CheckBox
    android:id="@+id/goalRowCB"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" />

<TextView
    android:id="@+id/goalRowTitle"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:clickable="true"
    android:gravity="center_horizontal"
    android:text="@string/dummyTxt"
    android:textColor="@color/TextColor"
    android:textSize="17sp" />



在方法定义中，在
getData
和括号
（）
之间有一个空格：

public List<RVData> getData () {
    ...
}

public List getData（）{
...
}

改为：

public List<RVData> getData() {  // <-- deleted space
    ...
}

公共列表getData（）{/更改

public RVData msetreecyclergoaltitle（视图）{
editGoalTitle=（EditText）findViewById（R.id.edit\u goalTitle）；
editGoalTitle.setText（R.string.dummyTxt）；
stringGoalTitle=editGoalTitle.getText（）.toString（）；
公共列表getData（）{
列表数据=新的ArrayList（）；
字符串[]标题={}；
如果（stringGoalTitle！=null）{
titles=新字符串[]{stringGoalTitle}；
}否则{
titles=新字符串[]{“DummyText1”}；
}
对于（inti=0；i，您的代码有很多地方出错

首先，这种方法毫无意义：

public RVData mSetRecyclerGoalTitle(View view) {

editGoalTitle = (EditText) findViewById(R.id.edit_goalTitle);
editGoalTitle.setText(R.string.dummyTxt);
stringGoalTitle = editGoalTitle.getText().toString();


public List<RVData> getData () {
    List<RVData> data = new ArrayList<>();
    String[] titles = {};
    if (stringGoalTitle != null) {
        titles = new String[]{stringGoalTitle};
    } else {
        titles = new String[]{"DummyText1"};
    }
    for (int i = 0; i <= titles.length; i++) {
        RVData current = new RVData();
        current.goalTitle = titles[i];
        data.add(current);
    }
        return data;
    }
}

但是，这种onClick方法也会失败，因为
MainActivity
膨胀了其他xml文件，而不是
activity\u new\u goal.xml
。只有在膨胀
activity\u new\u goal.xml的活动中放入
mstrecyclergoaltile
方法，这才有效。从我看来，您要做的是将一些信息从NewGoal活动返回到main活动。您无法访问其他活动的布局以恢复其视图的内容

这通常使用startActivityForResult完成

看看开发者参考资料：
下次请发布堆栈跟踪（错误日志），以便更容易了解代码的错误。
adapter=new RVAdapter（getApplicationContext（），getData（））；
&
editGoalTitle.settText（R.string.dummyTxt）；
&
mstrecyclergoaltitle（null）尝试N1to的解决方案后，它给了我以下信息：
adapter=new RVAdapter（getApplicationContext（），getData（））；
&
editGoalTitle.setText（R.string.dummyTxt）；
和
mstrecyclergoaltitle（null）
我已经告诉过你，你得到NPE是因为
edit\u goalTitle
不在
activity\u main.xml
中，所以你无法获得对EditText的引用。那么你能告诉我如何链接它，这样我就不会得到这个吗？我的意思是如何将它指向
activity\u new\u goal.xml
EditText？只需在谷歌上搜索一下如何找到它n布局。在您的情况下，您已经有了
NewGoal
，这是一个膨胀
activity\u new\u goal.xml
的活动。因此，如果您在那里使用
findViewById
，您将找到您的
edit\u goalttle
。