java - 单击 fragment 按钮时如何获取下一个 Activity

Question

嗨，当我在 View 1 中按下 Fab 时，我正在尝试获取我的 NextActivity

查看 1 个 xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <com.google.android.material.floatingactionbutton.FloatingActionButton
        android:id="@+id/Fbutton"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="300dp"
        android:layout_marginLeft="180dp"
        android:clickable="true"
        android:paddingRight="16dp"
        android:paddingBottom="16dp"

        />
</RelativeLayout>,

View.java

package com.example.myapplication;

import android.content.Intent;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;

import com.google.android.material.floatingactionbutton.FloatingActionButton;

public class View1 extends Fragment {
private FloatingActionButton mFab;
    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view=inflater.inflate(R.layout.view1, container, false);
       mFab.findViewById(R.id.Fbutton);
       mFab.setOnClickListener(new View.OnClickListener() {
           @Override
           public void onClick(View v) {
               Intent intent = new Intent(getActivity(),NextActivity.class);
               startActivity(intent);
           }
       });
        return view;
    }

}

错误

java.lang.NullPointerException:尝试在空对象引用上调用虚拟方法“android.view.View com.google.android.material.floatingactionbutton.FloatingActionButton.findViewById(int)” 在 com.example.myapplication.View1.onCreateView(View1.java:21)

我已经尝试过获取上下文()View1.this没有任何效果

Answer 1

您尚未完成 float 按钮分配。删除mFab.findViewById(R.id.Fbutton);这条线。添加

 mFab =  view.findViewById(R.id.Fbutton);

这里view用于从布局中获取 ID。