安卓天天练练（一）不讨巧的绝对布局

IDE 采用eclipse luna

使用了AbsoluteLayout标签后IDE立即开始警告：“AbsoluteLayout is deprecated”，不赞成使用绝对布局（无视它）

》需要注意

• 如果看到报错"[Accessibility]Missing conetent description attribute on image"教学中也有出现，无视之
• Graphical Layout的预览报java.lang错误却常常是xml标签未闭合，检查各标签>和/>
• <Button />和<TextView />等等，无value内容的标签均可改写为自闭合
• <EditText />可以从Graphical Layout工具的Palette中TextView分类任意可编辑文本框拖出来
• <ScrollView></ScrollView>需要闭合标签
• 手生敲xml注意区分android:@+id/和@id/
• objname.setOnClickListener不会自动完成，但是在其内部的new View.OnClickListener()可以自动生成重写以及定义onClick函数
• 熟练使用(tagname)findViewById(R.id.xxx)
• 书写getText().toString()和setText().toString()

src/com.narumi.absolutelayout/MainActivity.java

package com.narumi.absolutelayout;

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

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        final Button okButton  = (Button) findViewById(R.id.btnok);
        final Button cancelButton = (Button) findViewById(R.id.btcel);
        final EditText uid = (EditText) findViewById(R.id.etuid);
        final EditText pwd = (EditText) findViewById(R.id.etpwd);
        final EditText log = (EditText) findViewById(R.id.etres);
        okButton.setOnClickListener(
                new View.OnClickListener() {
                    
                    @Override
                    public void onClick(View v) {
                        // TODO Auto-generated method stub
                        String uidStr = uid.getText().toString();
                        String pwdStr = pwd.getText().toString();
                        log.append("用户名："+uidStr+"密码："+pwdStr+"
");
                    }
                } );
        
        cancelButton.setOnClickListener(
            new View.OnClickListener() {
                
                @Override
                public void onClick(View v) {
                    // TODO Auto-generated method stub
                    uid.setText("");
                    pwd.setText("");
                }
            } );
    }

    @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.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

下面两个自动生成的方法可以不要：

onCreateOptionsMenu

public boolean onOptionsItemSelected

编辑res/value中的string.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <string name="app_name">Android_6_3</string>
    <string name="uid">用户名</string>
    <string name="pvd">密码</string>
    <string name="ok">确定</string>
    <string name="cancel">取消</string>
</resources>

编辑res/layout中的activity_main.xml

<AbsoluteLayout 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="com.narumi.absolutelayout.MainActivity" >

    <TextView
        android:id="@+id/tvuid"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/uid" />

    <TextView
        android:id="@+id/tvpwd"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_x="21dp"
        android:layout_y="61dp"
        android:text="@string/pvd" />

    <EditText
        android:id="@+id/etuid"
        android:layout_width="167dp"
        android:layout_height="wrap_content"
        android:layout_x="61dp"
        android:layout_y="-12dp"
        android:ems="10"
        android:inputType="text" >
    </EditText>

    <EditText
        android:id="@+id/etpwd"
        android:layout_width="168dp"
        android:layout_height="34dp"
        android:layout_x="59dp"
        android:layout_y="55dp"
        android:ems="10"
        android:inputType="numberPassword" >
    </EditText>

    <ScrollView
        android:id="@+id/scrollView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_x="48dp"
        android:layout_y="144dp" >
    </ScrollView>

    <EditText
        android:id="@+id/etres"
        android:layout_width="wrap_content"
        android:layout_height="139dp"
        android:layout_x="31dp"
        android:layout_y="260dp"
        android:ems="10"
        android:inputType="text" >

    </EditText>

    <Button
        android:id="@+id/btnok"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_x="72dp"
        android:layout_y="175dp"
        android:text="@string/ok" />

    <Button
        android:id="@+id/btcel"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_x="165dp"
        android:layout_y="175dp"
        android:text="@string/cancel" />

</AbsoluteLayout>

就这么简单，一练结束。