布局属性

一、图片自适应占满

二、文字设定两行，超出两行在后面添加省略号

三、段落间距

package com.example.dangjiano;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.content.ContextCompat;
import android.content.Context;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.text.SpannableString;
import android.text.Spanned;
import android.text.style.ImageSpan;
import android.widget.TextView;
import java.util.ArrayList;
import java.util.List;
public class DetailPageActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_detail_page);
    }
    public static void setParagraphSpacing(Context context, TextView tv, String content, int paragraphSpacing, int lineSpacingExtra) {
        if (!content.contains("\n")) {
            tv.setText(content);
            return;
        }
        content = content.replace("\n", "\n\r");
        int previousIndex = content.indexOf("\n\r");
        //记录每个段落开始的index，第一段没有，从第二段开始
        List<Integer> nextParagraphBeginIndexes = new ArrayList<>();
        nextParagraphBeginIndexes.add(previousIndex);
        while (previousIndex != -1) {
            int nextIndex = content.indexOf("\n\r", previousIndex + 2);
            previousIndex = nextIndex;
            if (previousIndex != -1) {
                nextParagraphBeginIndexes.add(previousIndex);
            }
        }
        //获取行高（包含文字高度和行距）
        float lineHeight = tv.getLineHeight();
        //把\r替换成透明长方形（宽:1px，高：字高+段距）
        SpannableString spanString = new SpannableString(content);
        Drawable d = ContextCompat.getDrawable(context, R.drawable.paragraph_space);
        float density = context.getResources().getDisplayMetrics().density;
        //int强转部分为：行高 - 行距 + 段距
        d.setBounds(0, 0, 1, (int) ((lineHeight - lineSpacingExtra * density)
                                    / 1.2 + (paragraphSpacing - lineSpacingExtra) * density));
        for (int index : nextParagraphBeginIndexes) {
            // \r在String中占一个index
      spanString.setSpan(new ImageSpan(d), index + 1, index + 2,Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
        }
        tv.setText(spanString);
    }
}

四、行间距

五、取消radio前面的圆圈

  1.布局取消，并不能真正意义上的取消<br />![image.png](https://cdn.nlark.com/yuque/0/2021/png/1574587/1615887356941-4e857a11-6d86-4aea-a0a7-79360891df81.png#align=left&display=inline&height=157&margin=%5Bobject%20Object%5D&name=image.png&originHeight=157&originWidth=400&size=10703&status=done&style=none&width=400)<br />      2.逻辑取消，实现真正的取消

   LinearLayoutCompat.LayoutParams params = new LinearLayoutCompat.LayoutParams
            (ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
        LinearLayout ll = (LinearLayout) findViewById(R.id.activity_main);
        RadioButton button = new RadioButton(this);
        button.setText("这是代码创建的RadioButton");
//        button.setButtonDrawable(new ColorDrawable(Color.TRANSPARENT)); //取消圆圈
                button.setButtonDrawable(0);      //取消圆圈方式2 
        ll.addView(button, params);
    }

六、设置布局和文件：

1.可见（visible）：

    xml文件：android:visibility="visible"<br />        java代码：view.setVisibility(View.VISIBLE);

2.不可见（invisible）：

    xml文件：android:visibility="invidible"<br />        java代码：view.setVisibility(View.INVISIBLE);

3.隐藏（GONE）：

    xml文件：android:visibility="gone"<br />        java代码：view.setVisibility(View.GONE);