Android入门之EditText(纯java)

 Android入门之EditText(纯java)_第1张图片

import android.app.Activity;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.widget.*;

public class EditTextTest extends Activity {
   
	private LinearLayout mainLayout=null;
	
	private RelativeLayout layout=null;	
	private TextView tv1=null;		//标题		
	private TextView tv2=null;		//可输入剩余字符数
	private EditText et=null;		//输入框		
    
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mainLayout_init();
        setContentView(mainLayout);
    }
    /*mainLayout初始化*/
    void mainLayout_init(){
    	mainLayout=new LinearLayout(this);
    	LinearLayout.LayoutParams lp=new LinearLayout.LayoutParams(-1, -1);
    	mainLayout.setLayoutParams(lp);
    	mainLayout.setOrientation(LinearLayout.VERTICAL);
    	layout_init();
    	mainLayout.addView(layout);
    	et_init();
    	mainLayout.addView(et);
    }
    /*layout1初始化*/
    void layout_init(){
    	layout=new RelativeLayout(this);
    	RelativeLayout.LayoutParams lp=new RelativeLayout.LayoutParams(-1, -2);
    	layout.setLayoutParams(lp);
    	tv1_init();
    	layout.addView(tv1);
    	tv2_init();
    	layout.addView(tv2);
    }
    /*tv11初始化*/
    void tv1_init(){
    	tv1=new TextView(this);
    	RelativeLayout.LayoutParams lp=new RelativeLayout.LayoutParams(-2, -2);
    	lp.addRule(RelativeLayout.ALIGN_PARENT_LEFT);
    	tv1.setLayoutParams(lp);
    	tv1.setTextSize(30);
    	tv1.setText("请输入账号:");
    }
    /*tv12初始化*/
    void tv2_init(){
    	tv2=new TextView(this);
    	RelativeLayout.LayoutParams lp=new RelativeLayout.LayoutParams(-2, -2);
    	lp.addRule(RelativeLayout.ALIGN_PARENT_RIGHT);
    	tv2.setLayoutParams(lp);
    	tv2.setTextSize(30);
    	tv2.setText("12");
    }
    /*et1初始化*/
    void et_init(){
    	et=new EditText(this);
    	LinearLayout.LayoutParams lp=new LinearLayout.LayoutParams(-1,-2);
    	et.setLayoutParams(lp);
    	et.setSingleLine(true);
    	//字符变化监听
    	TextWatcher tw=new TextWatcher(){
			public void afterTextChanged(Editable s) {
				//限制输入,最多允许输入12个
				if(et.length()>12){
					//截取字符串,舍弃最后一个
					et.setText((et.getText()).subSequence(0, 12));
					//设置光标。由于用setText函数会导致光标复位,所以重新设置光标到末尾
					et.setSelection(12);
				}
				//显示剩余可输入字符数
				tv2.setText(String.valueOf(12-et.length()));
			}
			public void beforeTextChanged(CharSequence s, int start, int count,int after) {}
			public void onTextChanged(CharSequence s, int start, int before,int count) {}
    	};
    	et.addTextChangedListener(tw);
    }
}


 

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