Question

我正在使用Android工作室进行Android开发。我正在创建onclick按钮活动。我没有错误但是当我点击应用程序上的按钮时它显示“不幸的是应用程序已停止”。下面是我的fragment_main.xml和MainActivity.java的代码。请指导。 fragment_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context=".MainActivity$PlaceholderFragment">



<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/texthaiku"
    android:id="@+id/button"
    android:layout_alignParentTop="true"
    android:layout_toRightOf="@+id/editText"
    android:onClick="OnLoveButtonClicked"/>

<TextView
    android:text="@string/haiku"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/textView"
    android:layout_below="@+id/button"
    android:visibility="invisible"
    android:layout_alignParentLeft="true"
    android:layout_marginTop="33dp" />


</RelativeLayout>

MainActivity.java

package com.AndroidLove;

import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import android.widget.Button;
import android.os.Build;

public class MainActivity extends ActionBarActivity {

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

    if (savedInstanceState == null) {
        getSupportFragmentManager().beginTransaction()
                .add(R.id.container, new PlaceholderFragment())
                .commit();
    }
 }

    public void onLoveButtonClicked(View view) {
    TextView textView =(TextView) findViewById(R.id.textView);
    textView.setVisibility(View.VISIBLE);
    }
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {

    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.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.
    switch (item.getItemId()) {
        case R.id.action_settings:
            return true;
    }
    return super.onOptionsItemSelected(item);
    }

    /**
     * A placeholder fragment containing a simple view.
     */
    public static class PlaceholderFragment extends Fragment {

    public PlaceholderFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_main, container, false);
        return rootView;
        }
    }

  }

Answer 1

试试这个..

它会给NPE，因为 textView 位于fragment_main.xml内，然后您在单击函数内部启动该textview，这是错误的。在全局

中使用 textView

TextView textView;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.fragment_main, container, false);
    textView =(TextView) rootView.findViewById(R.id.textView);
    return rootView;
    }

和

public void onLoveButtonClicked(View view) {

    textView.setVisibility(View.VISIBLE);
}

Answer 2

您尚未在TextView

上初始化onCreateView()

所以在onCreateView()

上添加此行

textView =(TextView) rootView.findViewById(R.id.textView);

修改

也初始化你的按钮。

btn = (Button) rootView.findViewById(R.id.button);

Answer 3

你在哪里创建了容器，在你显示的xml中我看不到任何容器布局。没有R.id.container

Android应用程序错误“很遗憾应用已停止”

3 个答案: