[英]How to Open Fragment from MainActivity when Button is Clicked
我在 MainActivity 中实现一些按钮时遇到了挑战,当每个按钮被单击时,应该将我带到 Fragment Class,并且我还有其他按钮要设置以启动片段活动。 现在,这些片段通过适配器托管在 Tip4Activity 上。
我的问题是如何创建一个按钮,单击该按钮应将我带到 Page1Fragment? 然后通过可行的类似操作,我可以创建其他按钮
这就是我在MainActivity.java中所做的
Tips3 = (Button)findViewById(R.id.mybtn1);
Tips3.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Fragment fragment= new Page1Fragment();
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.container, fragment);
transaction.addToBackStack(null);
transaction.commit();
}
});
来自activity_main.xml的按钮
<Button android:id="@+id/mybtn1" style="?buttonBarButtonStyle" android:layout_width="300dp" android:layout_height="40dp" android:layout_marginTop="13dp" android:layout_weight="1" android:layout_gravity="center" android:text="The Preparation" android:textColor="#ffffff" android:textSize="17sp" android:textStyle="bold" />
这是我的Page1Fragment.java
private static final String TAG = "Page1Fragment ----- ; ";
// Store instance variables
private String title;
private int page;
private ConsentForm form;
//Store instance variables based on arguments passed
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
page = getArguments().getInt("SomeInt", 1);
title = getArguments().getString("someTitle");
}
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_page1, container, false);
// set the html content for TextView
TextView newTextView = (TextView) v.findViewById(R.id.Tv1);
newTextView.setText(Html.fromHtml(getString(R.string.htmlFormattedText1)));
return v;
}
// newInstance constructor for creating fragments with arguments
public static Page1Fragment newInstance(int page, String title) {
Page1Fragment Page1Fragment = new Page1Fragment();
Bundle args = new Bundle();
args.putInt("someInt", page);
args.putString("someTitle", title);
Page1Fragment.setArguments(args);
return Page1Fragment;
}
}
这是在适配器tips_4.xml的帮助下托管所有片段的活动
public class Tips_4 extends AppCompatActivity {
Toolbar toolbar;
TabLayout tabLayout;
ViewPager viewPager;
Button Tips3;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_tips_4);
//--------add click listener here ----------------------
Tips3 = (Button)findViewById(R.id.mybtn1);
Tips3.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Fragment fragment= new Page1Fragment();
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.container, fragment);
transaction.addToBackStack(null);
transaction.commit();
}
});
toolbar= findViewById(R.id.app_bar);
setSupportActionBar(toolbar);
ViewPager viewPager= (ViewPager) findViewById(R.id.view_pager);
viewPager.setAdapter(new SimpleFragmentPageAdapter(getSupportFragmentManager(),this));
//Attach the page change listener inside the activity
viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
// This method will be invoked when a new page becomes selected
@Override
public void onPageSelected(int position) {
Toast.makeText(Tips_4.this, "Selected Fragment Page:" + position, Toast.LENGTH_SHORT).show();
}
// This method will be invoked when the current page is scrolled
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetpixels) {
}
// Called when the scroll state changes:
//SCROLL_STATE_IDLE, SCROLL_STATE_DRAGGING, SCROLL_STATE_SETTLING
@Override
public void onPageScrollStateChanged(int state) {
}
});
tabLayout= (TabLayout) findViewById(R.id.tab_layout);
tabLayout.setupWithViewPager(viewPager);
}
这是异常跟踪
--------- beginning of crash
2020-07-20 15:58:48.515 15613-15613/com.joseph.advancedmaths E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.joseph.advancedmaths, PID: 15613
java.lang.IllegalArgumentException: No view found for id 0x7f080067 (com.joseph.advancedmaths:id/container) for fragment Page1Fragment{8075d59 #0 id=0x7f080067}
at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManager.java:1454)
at androidx.fragment.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManager.java:1784)
at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManager.java:1852)
at androidx.fragment.app.BackStackRecord.executeOps(BackStackRecord.java:802)
at androidx.fragment.app.FragmentManagerImpl.executeOps(FragmentManager.java:2625)
at androidx.fragment.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2411)
at androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManager.java:2366)
at androidx.fragment.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:2273)
at androidx.fragment.app.FragmentManagerImpl$1.run(FragmentManager.java:733)
at android.os.Handler.handleCallback(Handler.java:790)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6549)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:888)
如果您在活动的onCreate
方法中的setContentView
之后设置点击侦听器,您应该没有问题。 您甚至可以在onCreatedView
方法上执行此操作以防万一。
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_tips_4);
//--------add click listener here ----------------------
Tips3 = (Button)findViewById(R.id.mybtn1);
Tips3.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Fragment fragment= new Page1Fragment();
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.container, fragment);
transaction.addToBackStack(null);
transaction.commit();
}
});
toolbar= findViewById(R.id.app_bar);
setSupportActionBar(toolbar);
ViewPager viewPager= (ViewPager) findViewById(R.id.view_pager);
viewPager.setAdapter(new SimpleFragmentPageAdapter(getSupportFragmentManager(),this));
//Attach the page change listener inside the activity
viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
// This method will be invoked when a new page becomes selected
@Override
public void onPageSelected(int position) {
Toast.makeText(Tips_4.this, "Selected Fragment Page:" + position, Toast.LENGTH_SHORT).show();
}
// This method will be invoked when the current page is scrolled
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetpixels) {
}
// Called when the scroll state changes:
//SCROLL_STATE_IDLE, SCROLL_STATE_DRAGGING, SCROLL_STATE_SETTLING
@Override
public void onPageScrollStateChanged(int state) {
}
});
tabLayout= (TabLayout) findViewById(R.id.tab_layout);
tabLayout.setupWithViewPager(viewPager);
}
试试这个,让我知道它是如何工作的。
好吧,看起来片段没有显示,因为参数是 null。
public void onClick(View view) {
Fragment fragment = Page1Fragment.newInstance(1, "Hello");
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.container, fragment);
transaction.addToBackStack(null);
transaction.commit();
}
看看这个指令
Fragment fragment = Page1Fragment.newInstance(1, "Hello");
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