Layout1.1

Write the XML

Each layout file must contain exactly one root element, which must be a View or ViewGroup object

 

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="fill_parent" 
              android:layout_height="fill_parent" 
              android:orientation="vertical" >
    <TextView android:id="@+id/text"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:text="Hello, I am a TextView" />
    <Button android:id="@+id/button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Hello, I am a Button" />
</LinearLayout>

 

 

/**
	 * Activity启动时执行
	 */
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // 位于程序的第一行  加载xml布局
        setContentView(R.layout.activity_main);
    }

 

 

 

Attributes

ID：Any View object may have an integer ID associated with it, to uniquely identify the View within the tree（每个控件唯一一个标示符）

android:id="@+id/my_button"

Button myButton =(Button) findViewById(R.id.my_button);

 

package com.example.android_layout_line;

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends Activity {

	private Button button1;
	
	private Button button2;
	
	/**
	 * Activity启动时执行
	 */
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // 位于程序的第一行  加载xml布局
        setContentView(R.layout.activity_main);
        
        // 加载布局后才能获取布局中定义的各种控件 通过Id获取
        button1 = (Button) this.findViewById(R.id.register);
        button1.setOnClickListener(new View.OnClickListener() {
			
			@Override
			public void onClick(View v) {
				Toast.makeText(MainActivity.this, "注册....", 1).show();
			}
		});
        
        button2 = (Button) this.findViewById(R.id.login);
        button2.setOnClickListener(new View.OnClickListener() {
			
			@Override
			public void onClick(View v) {
				Toast.makeText(MainActivity.this, "登录....", 1).show();
			}
		});
    }


    @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;
    }
    
}

 

 

Linear Layout

 LinearLayout is a view group that aligns all children in a single direction, vertically or horizontally.（所有子组件只有一个方向，横向或者纵向）

 

<LinearLayout 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:orientation="vertical"
    tools:context=".MainActivity" >

    <LinearLayout 
        android:layout_width="match_parent"
	    android:layout_height="wrap_content"
	    android:orientation="horizontal"
        >
	    
        <TextView
	        android:id="@+id/textView1"
	        android:layout_width="wrap_content"
	        android:layout_height="wrap_content"
	        android:text="用户名" />
        
        <EditText
	        android:id="@+id/editText1"
	        android:layout_width="wrap_content"
	        android:layout_height="wrap_content"
	        android:ems="10"
	        android:inputType="textPassword" >
	
	        <requestFocus />
	    </EditText>
        
    </LinearLayout>
    
    <LinearLayout 
        android:layout_width="match_parent"
	    android:layout_height="wrap_content"
	    android:orientation="horizontal"
        >
        
        <TextView
	        android:id="@+id/textView2"
	        android:layout_width="wrap_content"
	        android:layout_height="wrap_content"
	        android:text="密码" />
        
        <EditText
	        android:id="@+id/editText2"
	        android:layout_width="wrap_content"
	        android:layout_height="wrap_content"
	        android:ems="10"
	        android:inputType="textPassword" />
    </LinearLayout>
    
</LinearLayout>

 

 

android:gravity  布局中子元素位于该布局方位
android:layout_gravity   布局方位

Layout Weight

android:layout_weight="1"

 Default weight is zero.

This attribute assigns an "importance" value to a view in terms of how much space is should occupy on the screen