onClickListener在setContentView之后无法正常工作

时间:2013-05-28 16:25:38

标签: java android button onclicklistener

MainActivity

package com.Kevious.Kevin;

import android.app.*;
import android.os.*;
import android.view.*;
import android.widget.*;
import android.view.View.*;
import android.opengl.*;
import android.content.*;
import android.text.*;
import java.net.*;

public class MainActivity extends Activity
{
String passw;
String value = "Test";
int i = 1;
TextView textView;
Button button;
EditText editText;


@Override
public void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
textView = (TextView) findViewById(R.id.textView);
button = (Button) findViewById(R.id.button);

button.setOnClickListener(new View.OnClickListener() {

public void onClick(View p1)
{
loadMethod();

}

}
);

editText = (EditText) findViewById(R.id.editText);

editText.addTextChangedListener(new TextWatcher(){

public void beforeTextChanged(CharSequence p1, int p2, int p3, int p4)
{
}

public void onTextChanged(CharSequence p1, int p2, int p3, int p4)
{

// TODO: Implement this method

passw = editText.getText().toString();
textView.setText(passw);
passw = textView.getText().toString();
}

public void afterTextChanged(Editable p1)
{

}
}
);
}

public void loadMethod()
{
passwCheck();
}


public void passwCheck(){

passw = textView.getText().toString();

if (passw.equals("kev"))
{
Toast.makeText(this, "corrrect " + passw, Toast.LENGTH_SHORT).show();
setContentView(R.layout.nextactivity);
} else {
Toast.makeText(this, "incorrect " + passw, Toast.LENGTH_SHORT).show();
}
}
}

NextActivity

package com.Kevious.Kevin;
import android.os.*;
import android.content.*;
import android.app.*;
import android.widget.*;
import android.view.View.*;
import android.view.*;

public class NextActivity extends Activity
{
Button button2;
TextView textView2;
@Override public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
textView2 = (TextView) findViewById(R.id.textView2);
textView2.setText("Welcome Kevin");
button2 = (Button) findViewById(R.id.button2);
button2.setOnClickListener(new OnClickListener(){
public void onClick(View p1)
{
textView2.setText("button clicked");
buttonclick2();
}
}
);
}


public void buttonclick2(){


Toast.makeText(this, "logged out", Toast.LENGTH_SHORT).show();

setContentView(R.layout.main);
}
}

我是stackoverflow的新手,所以我希望我正确地创建它。如果我做错了,我道歉。

我正在学习Android开发,只是尝试和创建我的第一个应用程序,不知怎的,我遇到了一个问题,即我的一个按钮不起作用,即使我已正确添加按钮监听器。

当我在主布局上键入“kev”作为密码并按下按钮时,它会通过“setContentView(.....)”将我带到NextActivity Layout,这样可以正常工作。

问题是,当我在NextActivity屏幕时,它会有一个按钮。不知怎的,当我点击那个按钮时,它什么也没做。我确信代码是对的。有人可以帮助我吗?

由于

5 个答案:

答案 0 :(得分:4)

setContentView()无法启动新活动。要做到这一点,运行这样的东西:

Intent intent = new Intent(this, NextActivity.class);
startActivity(intent);

在新的Activity中运行setContentView,然后在那里设置任何onClickListeners。

答案 1 :(得分:2)

除了发布的答案。您正在尝试初始化视图而不将内容设置为NextActivity中的活动。您可以通过查看当前视图层次结构的视图来查看活动。

如果您需要从一个活动导航到另一个活动,请点击按钮

     startActivity(new Intent(ActivityName.this,NextActivity.class); or
     startActiivty(new Intent("packagename.NextActivity); 

的setContentView。您误解了setContentView的用途。

http://developer.android.com/reference/android/app/Activity.html#setContentView(int)

将活动内容设置为显式视图

此视图直接放置在活动的视图层次结构中。它本身可以是一个复杂的视图层次结构。调用此方法时,将忽略指定视图的布局参数。默认情况下,视图的宽度和高度都设置为MATCH_PARENT。要使用您自己的布局参数,请调用setContentView(android.view.View,android.view.ViewGroup.LayoutParams)。

参数

     view   The desired content to display.

在你的NextActivity中

      @Override 
      public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.main); 
       // this should be first not in buttonclick2()
      textView2 = (TextView) findViewById(R.id.textView2);
       // then initialize views.  
      ...
      } 

示例:

  public class MainActivity extends Activity
 {
 String passw;
 TextView textView;
 Button button;
 EditText editText;


@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textView = (TextView) findViewById(R.id.textView1);
editText = (EditText) findViewById(R.id.editText1);
button = (Button) findViewById(R.id.button1);
button.setOnClickListener(new View.OnClickListener() {
public void onClick(View p1)
{
  passw = editText.getText().toString();
  if (passw.equals("kev"))
  {
  Toast.makeText(MainActivity.this, "corrrect " + passw, Toast.LENGTH_SHORT).show();
  startActivity(new Intent(MainActivity.this,NextActivity.class));
  } else {
  Toast.makeText(MainActivity.this, "incorrect " + passw, Toast.LENGTH_SHORT).show();
  }
}
});
}
}

activity_main.xml中

<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:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >

<EditText
    android:id="@+id/editText1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_alignParentRight="true"
    android:layout_alignParentTop="true"
    android:layout_marginTop="20dp"
    android:ems="10"
    android:inputType="textPassword" >

    <requestFocus />
</EditText>

<TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignLeft="@+id/editText1"
    android:layout_alignParentTop="true"
    android:layout_marginLeft="83dp"
    android:text="Password" />

<Button
    android:id="@+id/button1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignLeft="@+id/textView1"
    android:layout_alignParentBottom="true"
    android:layout_marginLeft="39dp"
    android:text="Button" />

</RelativeLayout>

NextActivity.java

public class NextActivity extends Activity
{
Button button2;
TextView textView2;
@Override 
 public void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.next);
  textView2 = (TextView) findViewById(R.id.textView1);
  textView2.setText("Welcome Kevin");
  button2 = (Button) findViewById(R.id.button1);
  button2.setOnClickListener(new OnClickListener(){
  public void onClick(View p1)
  {
    textView2.setText("button clicked");
  }
  });
 }
 } 

next.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >

<TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerHorizontal="true"
    android:layout_centerVertical="true"
    android:text="TextView" />

<Button
    android:id="@+id/button1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignLeft="@+id/textView1"
    android:layout_alignParentBottom="true"
    android:text="Button" />

</RelativeLayout>

的Manifest.xml

    <activity
        android:name="com.example.MainActivity"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
     <activity
        android:name="com.example.NextActivity"
        android:label="@string/app_name" >

    </activity>

答案 2 :(得分:0)

实际上你并没有导航到NextActivity。您处于MainActivity本身,您刚刚动态更改了布局。要导航到NextActivity,请使用

startActivity(new Intent(MainActivity.this,NextActivity.class));

在NextActivity的onCreate()方法中设置你的布局并尝试你想要做的事情。

答案 3 :(得分:0)

不建议在同一个活动中多次调用setContentView()。请参阅:Android: switching screens with new activity or just changing content view

此外,您需要通过以下方式启动NextActivity:

Intent intent = new Intent(this, NextActivity.class);
startActivity(intent);

目前,您只是在不添加活动功能的情况下更改UI。

答案 4 :(得分:0)

if (passw.equals("kev"))
{
Toast.makeText(this, "corrrect " + passw, Toast.LENGTH_SHORT).show();
Intent intent = new Intent(getApplicationContext(), NextActivity.class);
startActivity(intent);
} else {
Toast.makeText(this, "incorrect " + passw, Toast.LENGTH_SHORT).show();
}
}

您是否愿意为下一次活动使用

Intent intent = new Intent(getApplicationContext(), NextActivity.class);
intent.putExtra("your_key", your_value);
intent.putExtra("your_next_key", your_next_value);
startActivity(intent);

并且不要忘记在你的画面中注册你的活动!确保它拼写为你的.java类(区分大小写!)

AndroidManifest.xlm

  <application
        android:icon="@drawable/logo"
        android:label="@string/app_name" >
       <activity
            android:name=".MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity
            android:name=".NextActivity" />
  </application>