如何创建Fragment? Fragment通常创建在activity下,如果我们希望创建一个Fragment,可以在activity对应的布局文件中增加fragment节点(就跟清单文件一样),然后为该节点增加name或者class属性,绑定一个待实例化的Fragment类。具体步骤如下所示: 1.在activity布局下增加fragment节点:
2.创建Fragment类:package com.example.fragmentdemo1;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
public class Fragment1 extends Fragment
{
private TextView tv = null;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
{
View view = inflater.inflate(R.layout.f1,container);
tv = (TextView) view.findViewById(R.id.tv1);
return view;
}
public void setText(String text)
{
tv.setText(text);
}
}
3.Fragment类对应的布局
经过上面几个步骤,fragment就被创建好了,下面当activity被创建后,fragment就能被显示出来。 创建向下兼容的Fragment support.v4包中提供了也提供了Fragment类,使用v4包的fragment兼容性会更好。 使用方式: 1.activity继承v4包中的FragmentActivity 2.必须导入v4包中的Fragment 3.如果你要使用FragmentManager,必须使用getSupportFragmentManager(); 注意:布局中的fragment节点不用修改,仍然是fragment! Fragment间的通讯 因为每个fragment都会关联一个activity,所以只要获取这个activity,就能从activity中获取其他fragment,像这样
getActivity().getSupportFragmentManager().findFragmentById(R.id.fg1);
案例: 通过点击一个fragment上的按钮设置另一个fragment的文本: fragment1:
package com.example.fragmentdemo1;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
public class Fragment1 extends Fragment
{
private TextView tv = null;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
{
View view = inflater.inflate(R.layout.f1,container);
tv = (TextView) view.findViewById(R.id.tv1);
return view;
}
public void setText(String text)
{
tv.setText(text);
}
}
布局:
fragment2:
package com.example.fragmentdemo1;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.TextView;
public class Fragment2 extends Fragment
{
private Button but = null;
private TextView tv = null;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
{
View view = inflater.inflate(R.layout.f2, container);
but = (Button) view.findViewById(R.id.but);
tv = (TextView) view.findViewById(R.id.tv2);
return view;
}
@Override
public void onActivityCreated(Bundle savedInstanceState)
{
super.onActivityCreated(savedInstanceState);
but.setOnClickListener(new OnClickListener()
{
@Override
public void onClick(View v)
{
Fragment1 f1 = (Fragment1) Fragment2.this.getActivity().getSupportFragmentManager().findFragmentById(R.id.fg1);
f1.setText("哈哈");
}
});
}
}
布局:
Mainactivity:
package com.example.fragmentdemo1;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
public class MainActivity extends FragmentActivity
{
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
}
布局:
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
Display display = getWindowManager().getDefaultDisplay();
if (display.getWidth() > display.getHeight()) {
Fragment1 fragment1 = new Fragment1();
ft.replace(android.R.id.content, fragment1).commit();
} else {
Fragment2 fragment2 = new Fragment2();
ft.replace(android.R.id.content, fragment2).commit();
}
onDestroyView:Fragment中的布局被移除时调用
onDetach:Fragment和Activity解除关联的时候调用
大家可以重写所有生命周期方法,然后通过打log的方式观察生命周期,这里就不贴代码了。