Android学习笔记（四）Android 组件

EditText和setOnKeyListener事件实现文本处理 

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package com.example.test12;

import android.os.Bundle;
import android.app.Activity;
import android.view.KeyEvent;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import android.support.v4.app.NavUtils;

public class MainActivity extends Activity {

    private TextView text;
    private EditText edit;
    
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        text=(TextView)findViewById(R.id.textView1);
        edit=(EditText)findViewById(R.id.editText1);
        
        edit.setOnKeyListener(editlistener);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }

    View.OnKeyListener editlistener=new View.OnKeyListener() {
        
        public boolean onKey(View v, int keyCode, KeyEvent event) {
            // TODO Auto-generated method stub
            text.setText(edit.getText());
            return false;
        }
    };
}

带背景图片的按钮

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　　使用ImageButton来实现带背景图片的按钮。

　　OnFocusChangeListener焦点变化监听

　　ImageButton.setImageResourse()用来指定按钮的背景颜色

package com.example.test13;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.TextView;
import android.support.v4.app.NavUtils;

public class MainActivity extends Activity {

    private TextView tv;
    private ImageButton ibt;
    private Button bt;
    
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        tv=(TextView)findViewById(R.id.textView1);
        ibt=(ImageButton)findViewById(R.id.imageButton1);
        bt=(Button)findViewById(R.id.button1);
        
        ibt.setOnFocusChangeListener(focusChange);
        bt.setOnClickListener(clicked);
        
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }
    
    View.OnFocusChangeListener focusChange=new View.OnFocusChangeListener() {
        
        public void onFocusChange(View v, boolean hasFocus) {
            // TODO Auto-generated method stub
            if(hasFocus){
                tv.setText("Got Focus!!!");
                ibt.setImageResource(R.drawable.image1);
            }
            else{
                tv.setText("Lost Focus!!!");
                ibt.setImageResource(R.drawable.image2);
            }
        }
    };
    
    View.OnClickListener clicked=new View.OnClickListener() {
        
        public void onClick(View v) {
            // TODO Auto-generated method stub
            if(tv.getText()=="Got Focus!!!"){
                tv.setText("Lost Focus!!!");
                ibt.setImageResource(R.drawable.image2);
            }
            else{
                tv.setText("Got Focus!!!");
                ibt.setImageResource(R.drawable.image1);
            }
        }
    };   
}

Toast实现提示条(Toast总结)

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Toast.makeText()让文字显示与Toast对象中，会显示一段时间后自动消失。

Toast.makeText(
    MainActivity.this,
    "这个是Toast.makeText提示",
    Toast.LENGTH_LONG).show();

CheckBox和RadioButton复选框

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　　通过CheckBox.setOnCheckedChangeLister来监听CheckBox

相框的实现

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可以通过ImageButton和ImageView来实现，推荐ImageButton，它可以直接添加点击监听

java.io.File实现文件搜索

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在JAVA I/O的API中，提供了java.io.File对象。

package com.example.test14;

import java.io.File;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import android.support.v4.app.NavUtils;

public class MainActivity extends Activity {

    private TextView result;
    private Button bt;
    private EditText edit;
    
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        result=(TextView)findViewById(R.id.textView2);
        bt=(Button)findViewById(R.id.button1);
        edit=(EditText)findViewById(R.id.editText1);
        
        bt.setOnClickListener(new Button.OnClickListener() {
            
            public void onClick(View v) {
                // TODO Auto-generated method stub
                String keyword=edit.getText().toString();
                if(keyword.equals("")){
                    Toast.makeText(
                            MainActivity.this,
                            "不能为空!",
                            Toast.LENGTH_LONG).show();
                }
                else{
                    result.setText(searchFile(keyword));
                }
            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }

    private String searchFile(String Keyword){
        String searchResult="";
        File[] files=new File("/").listFiles();
        for(File f:files){
            if(f.getName().indexOf(Keyword)>=0)
                searchResult+=f.getPath()+"\n";// \n换行
        }
        if(searchResult.equals(""))
            searchResult="找不到文件!!!!";
        return searchResult;
    }
}