單擊按鈕時如何從 MainActivity 打開 Fragment

Question

我在 MainActivity 中實現一些按鈕時遇到了挑戰，當每個按鈕被單擊時，應該將我帶到 Fragment Class，並且我還有其他按鈕要設置以啟動片段活動。 現在，這些片段通過適配器托管在 Tip4Activity 上。

我的問題是如何創建一個按鈕，單擊該按鈕應將我帶到 Page1Fragment？ 然后通過可行的類似操作，我可以創建其他按鈕

這就是我在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();
            }
        });

來自activity_main.xml的按鈕

 <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" />

這是我的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;
    }
}

這是在適配器tips_4.xml的幫助下托管所有片段的活動

 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);


    }

這是異常跟蹤

 --------- 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)

Answer 1

如果您在活動的onCreate方法中的setContentView之后設置點擊偵聽器，您應該沒有問題。 您甚至可以在onCreatedView方法上執行此操作以防萬一。

@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);


}

試試這個，讓我知道它是如何工作的。

Answer 2

好吧，看起來片段沒有顯示，因為參數是 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();
        }

看看這個指令

Fragment fragment = Page1Fragment.newInstance(1, "Hello");