设置tablayout下划线长度的方法(android.support.design.widget.TabLayout)

public static void setIndicator(Context context, TabLayout tabs, int leftDip, int rightDip) {

Class> tabLayout = tabs.getClass();

Field tabStrip = null;

try {

tabStrip = tabLayout.getDeclaredField("mTabStrip");

} catch (NoSuchFieldException e) {

e.printStackTrace();

}

tabStrip.setAccessible(true);

LinearLayout ll_tab = null;

try {

ll_tab = (LinearLayout) tabStrip.get(tabs);

} catch (IllegalAccessException e) {

e.printStackTrace();

}

int left = (int) (getDisplayMetrics(context).density * leftDip);

int right = (int) (getDisplayMetrics(context).density * rightDip);

for (int i = 0; i < ll_tab.getChildCount(); i++) {

View child = ll_tab.getChildAt(i);

child.setPadding(0, 0, 0, 0);

LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(0, LinearLayout.LayoutParams.MATCH_PARENT, 1);

params.leftMargin = left;

params.rightMargin = right;

child.setLayoutParams(params);

child.invalidate();

}

}

public static DisplayMetrics getDisplayMetrics(Context context) {

DisplayMetrics metric = new DisplayMetrics();

((Activity) context).getWindowManager().getDefaultDisplay().getMetrics(metric);

return metric;

}

public static float getPXfromDP(float value, Context context) {

return TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, value,

context.getResources().getDisplayMetrics());

}

调用方式，在你的activity里面

tab_title = (TabLayout) findViewById(R.id.tab_fragment_title);

tab_title.post(new Runnable() {

@Override

public void run() {

setIndicator(PigTallyActivity.this,tab_title,50,50);

}

});